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* [PATCH 1/2 v5] serial: mctrl_gpio: Check if GPIO property exisits before requesting it
@ 2019-06-11 10:56 Stefan Roese
  2019-06-11 10:56 ` [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers Stefan Roese
  0 siblings, 1 reply; 10+ messages in thread
From: Stefan Roese @ 2019-06-11 10:56 UTC (permalink / raw)
  To: linux-serial
  Cc: linux-kernel, Mika Westerberg, Andy Shevchenko, Yegor Yefremov,
	Greg Kroah-Hartman, Giulio Benetti

This patch adds a check for the GPIOs property existence, before the
GPIO is requested. This fixes an issue seen when the 8250 mctrl_gpio
support is added (2nd patch in this patch series) on x86 platforms using
ACPI.

Here Mika's comments from 2016-08-09:

"
I noticed that with v4.8-rc1 serial console of some of our Broxton
systems does not work properly anymore. I'm able to see output but input
does not work.

I bisected it down to commit 4ef03d328769eddbfeca1f1c958fdb181a69c341
("tty/serial/8250: use mctrl_gpio helpers").

The reason why it fails is that in ACPI we do not have names for GPIOs
(except when _DSD is used) so we use the "idx" to index into _CRS GPIO
resources. Now mctrl_gpio_init_noauto() goes through a list of GPIOs
calling devm_gpiod_get_index_optional() passing "idx" of 0 for each. The
UART device in Broxton has following (simplified) ACPI description:

    Device (URT4)
    {
        ...
        Name (_CRS, ResourceTemplate () {
            GpioIo (Exclusive, PullDefault, 0x0000, 0x0000, IoRestrictionOutputOnly,
                    "\\_SB.GPO0", 0x00, ResourceConsumer)
            {
                0x003A
            }
            GpioIo (Exclusive, PullDefault, 0x0000, 0x0000, IoRestrictionOutputOnly,
                    "\\_SB.GPO0", 0x00, ResourceConsumer)
            {
                0x003D
            }
        })

In this case it finds the first GPIO (0x003A which happens to be RX pin
for that UART), turns it into GPIO which then breaks input for the UART
device. This also breaks systems with bluetooth connected to UART (those
typically have some GPIOs in their _CRS).

Any ideas how to fix this?

We cannot just drop the _CRS index lookup fallback because that would
break many existing machines out there so maybe we can limit this to
only DT enabled machines. Or alternatively probe if the property first
exists before trying to acquire the GPIOs (using
device_property_present()).
"

This patch implements the fix suggested by Mika in his statement above.

Signed-off-by: Stefan Roese <sr@denx.de>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Yegor Yefremov <yegorslists@googlemail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Giulio Benetti <giulio.benetti@micronovasrl.com>
---
v5:
- Simplified the code a bit (Andy)
- Added gpio_str == NULL handling (Andy)

v4:
- Add missing free() calls (Johan)
- Added Mika's reviewed by tag
- Added Johan to Cc

v3:
- No change

v2:
- Include the problem description and analysis from Mika into the commit
  text, as suggested by Greg.

 drivers/tty/serial/serial_mctrl_gpio.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/tty/serial/serial_mctrl_gpio.c b/drivers/tty/serial/serial_mctrl_gpio.c
index 39ed56214cd3..65348887a749 100644
--- a/drivers/tty/serial/serial_mctrl_gpio.c
+++ b/drivers/tty/serial/serial_mctrl_gpio.c
@@ -116,6 +116,19 @@ struct mctrl_gpios *mctrl_gpio_init_noauto(struct device *dev, unsigned int idx)
 
 	for (i = 0; i < UART_GPIO_MAX; i++) {
 		enum gpiod_flags flags;
+		char *gpio_str;
+		bool present;
+
+		/* Check if GPIO property exists and continue if not */
+		gpio_str = kasprintf(GFP_KERNEL, "%s-gpios",
+				     mctrl_gpios_desc[i].name);
+		if (!gpio_str)
+			continue;
+
+		present = device_property_present(dev, gpio_str);
+		kfree(gpio_str);
+		if (!present)
+			continue;
 
 		if (mctrl_gpios_desc[i].dir_out)
 			flags = GPIOD_OUT_LOW;
-- 
2.22.0


^ permalink raw reply	[flat|nested] 10+ messages in thread

* [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers
  2019-06-11 10:56 [PATCH 1/2 v5] serial: mctrl_gpio: Check if GPIO property exisits before requesting it Stefan Roese
@ 2019-06-11 10:56 ` Stefan Roese
  2019-06-11 12:44   ` Andy Shevchenko
  2019-06-18  7:49   ` Greg Kroah-Hartman
  0 siblings, 2 replies; 10+ messages in thread
From: Stefan Roese @ 2019-06-11 10:56 UTC (permalink / raw)
  To: linux-serial
  Cc: linux-kernel, Yegor Yefremov, Mika Westerberg, Andy Shevchenko,
	Giulio Benetti, Greg Kroah-Hartman

From: Yegor Yefremov <yegorslists@googlemail.com>

This patch permits the usage for GPIOs to control
the CTS/RTS/DTR/DSR/DCD/RI signals.

Changed by Stefan:
Only call mctrl_gpio_init(), if the device has no ACPI companion device
to not break existing ACPI based systems. Also only use the mctrl_gpio_
functions when "gpios" is available.

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Roese <sr@denx.de>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Giulio Benetti <giulio.benetti@micronovasrl.com>
Cc: Yegor Yefremov <yegorslists@googlemail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
v5:
- Dropped a few "if (up->gpios)" checks, as the mctrl_gpio_foo() API
  handles gpios == NULL (return)
- 8250_omap: Changed "IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(up->gpios, ...))"
  to "up->gpios == NULL", as mctrl_gpio_to_gpiod() does not handle
  gpios == NULL correctly.

v4:
- Added Mika's reviewed by tag
- Added Johan to Cc

v3:
- Only call mctrl_gpio_init(), if the device has no ACPI companion device
  to not break existing ACPI based systems, as suggested by Andy

v2:
- No change

Please note that this patch was already applied before [1]. And later
reverted [2] because it introduced problems on some x86 based boards
(ACPI GPIO related). Here a detailed description of the issue at that
time:

https://lkml.org/lkml/2016/8/9/357
http://www.spinics.net/lists/linux-serial/msg23071.html

This is a re-send of the original patch that was applied at that time.
With patch 1/2 from this series this issue should be fixed now (please
note that I can't test it on such an x86 platform causing these
problems).

Andy (or Mika), perhaps it would be possible for you to test this
patch again, now with patch 1/2 of this series applied as well?
That would be really helpful.

Thanks,
Stefan

[1] 4ef03d328769 ("tty/serial/8250: use mctrl_gpio helpers")
[2] 5db4f7f80d16 ("Revert "tty/serial/8250: use mctrl_gpio helpers"")

 .../devicetree/bindings/serial/8250.txt       | 19 +++++++++
 drivers/tty/serial/8250/8250.h                | 40 ++++++++++++++++++-
 drivers/tty/serial/8250/8250_core.c           | 17 ++++++++
 drivers/tty/serial/8250/8250_omap.c           | 29 ++++++++------
 drivers/tty/serial/8250/8250_port.c           |  7 ++++
 drivers/tty/serial/8250/Kconfig               |  1 +
 include/linux/serial_8250.h                   |  1 +
 7 files changed, 100 insertions(+), 14 deletions(-)

diff --git a/Documentation/devicetree/bindings/serial/8250.txt b/Documentation/devicetree/bindings/serial/8250.txt
index 3cba12f855b7..20d351f268ef 100644
--- a/Documentation/devicetree/bindings/serial/8250.txt
+++ b/Documentation/devicetree/bindings/serial/8250.txt
@@ -53,6 +53,9 @@ Optional properties:
   programmable TX FIFO thresholds.
 - resets : phandle + reset specifier pairs
 - overrun-throttle-ms : how long to pause uart rx when input overrun is encountered.
+- {rts,cts,dtr,dsr,rng,dcd}-gpios: specify a GPIO for RTS/CTS/DTR/DSR/RI/DCD
+  line respectively. It will use specified GPIO instead of the peripheral
+  function pin for the UART feature. If unsure, don't specify this property.
 
 Note:
 * fsl,ns16550:
@@ -74,3 +77,19 @@ Example:
 		interrupts = <10>;
 		reg-shift = <2>;
 	};
+
+Example for OMAP UART using GPIO-based modem control signals:
+
+	uart4: serial@49042000 {
+		compatible = "ti,omap3-uart";
+		reg = <0x49042000 0x400>;
+		interrupts = <80>;
+		ti,hwmods = "uart4";
+		clock-frequency = <48000000>;
+		cts-gpios = <&gpio3 5 GPIO_ACTIVE_LOW>;
+		rts-gpios = <&gpio3 6 GPIO_ACTIVE_LOW>;
+		dtr-gpios = <&gpio1 12 GPIO_ACTIVE_LOW>;
+		dsr-gpios = <&gpio1 13 GPIO_ACTIVE_LOW>;
+		dcd-gpios = <&gpio1 14 GPIO_ACTIVE_LOW>;
+		rng-gpios = <&gpio1 15 GPIO_ACTIVE_LOW>;
+	};
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index ebfb0bd5bef5..441aab94264b 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -11,6 +11,8 @@
 #include <linux/serial_reg.h>
 #include <linux/dmaengine.h>
 
+#include "../serial_mctrl_gpio.h"
+
 struct uart_8250_dma {
 	int (*tx_dma)(struct uart_8250_port *p);
 	int (*rx_dma)(struct uart_8250_port *p);
@@ -142,11 +144,47 @@ void serial8250_em485_destroy(struct uart_8250_port *p);
 static inline void serial8250_out_MCR(struct uart_8250_port *up, int value)
 {
 	serial_out(up, UART_MCR, value);
+
+	if (up->gpios) {
+		int mctrl_gpio = 0;
+
+		if (value & UART_MCR_RTS)
+			mctrl_gpio |= TIOCM_RTS;
+		if (value & UART_MCR_DTR)
+			mctrl_gpio |= TIOCM_DTR;
+
+		mctrl_gpio_set(up->gpios, mctrl_gpio);
+	}
 }
 
 static inline int serial8250_in_MCR(struct uart_8250_port *up)
 {
-	return serial_in(up, UART_MCR);
+	int mctrl;
+
+	mctrl = serial_in(up, UART_MCR);
+
+	if (up->gpios) {
+		int mctrl_gpio = 0;
+
+		/* save current MCR values */
+		if (mctrl & UART_MCR_RTS)
+			mctrl_gpio |= TIOCM_RTS;
+		if (mctrl & UART_MCR_DTR)
+			mctrl_gpio |= TIOCM_DTR;
+
+		mctrl_gpio = mctrl_gpio_get_outputs(up->gpios, &mctrl_gpio);
+		if (mctrl_gpio & TIOCM_RTS)
+			mctrl |= UART_MCR_RTS;
+		else
+			mctrl &= ~UART_MCR_RTS;
+
+		if (mctrl_gpio & TIOCM_DTR)
+			mctrl |= UART_MCR_DTR;
+		else
+			mctrl &= ~UART_MCR_DTR;
+	}
+
+	return mctrl;
 }
 
 #if defined(__alpha__) && !defined(CONFIG_PCI)
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index e441221e04b9..a4470771005f 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -14,6 +14,7 @@
  *	      serial8250_register_8250_port() ports
  */
 
+#include <linux/acpi.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/ioport.h>
@@ -982,6 +983,8 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
 
 	uart = serial8250_find_match_or_unused(&up->port);
 	if (uart && uart->port.type != PORT_8250_CIR) {
+		struct mctrl_gpios *gpios;
+
 		if (uart->port.dev)
 			uart_remove_one_port(&serial8250_reg, &uart->port);
 
@@ -1016,6 +1019,20 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
 		if (up->port.flags & UPF_FIXED_TYPE)
 			uart->port.type = up->port.type;
 
+		/*
+		 * Only call mctrl_gpio_init(), if the device has no ACPI
+		 * companion device
+		 */
+		if (!has_acpi_companion(uart->port.dev)) {
+			gpios = mctrl_gpio_init(&uart->port, 0);
+			if (IS_ERR(gpios)) {
+				if (PTR_ERR(gpios) != -ENOSYS)
+					return PTR_ERR(gpios);
+			} else {
+				uart->gpios = gpios;
+			}
+		}
+
 		serial8250_set_defaults(uart);
 
 		/* Possibly override default I/O functions.  */
diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index 0a8316632d75..620330599d39 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -141,18 +141,20 @@ static void omap8250_set_mctrl(struct uart_port *port, unsigned int mctrl)
 
 	serial8250_do_set_mctrl(port, mctrl);
 
-	/*
-	 * Turn off autoRTS if RTS is lowered and restore autoRTS setting
-	 * if RTS is raised
-	 */
-	lcr = serial_in(up, UART_LCR);
-	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
-	if ((mctrl & TIOCM_RTS) && (port->status & UPSTAT_AUTORTS))
-		priv->efr |= UART_EFR_RTS;
-	else
-		priv->efr &= ~UART_EFR_RTS;
-	serial_out(up, UART_EFR, priv->efr);
-	serial_out(up, UART_LCR, lcr);
+	if (up->gpios == 0) {
+		/*
+		 * Turn off autoRTS if RTS is lowered and restore autoRTS
+		 * setting if RTS is raised
+		 */
+		lcr = serial_in(up, UART_LCR);
+		serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+		if ((mctrl & TIOCM_RTS) && (port->status & UPSTAT_AUTORTS))
+			priv->efr |= UART_EFR_RTS;
+		else
+			priv->efr &= ~UART_EFR_RTS;
+		serial_out(up, UART_EFR, priv->efr);
+		serial_out(up, UART_LCR, lcr);
+	}
 }
 
 /*
@@ -453,7 +455,8 @@ static void omap_8250_set_termios(struct uart_port *port,
 	priv->efr = 0;
 	up->port.status &= ~(UPSTAT_AUTOCTS | UPSTAT_AUTORTS | UPSTAT_AUTOXOFF);
 
-	if (termios->c_cflag & CRTSCTS && up->port.flags & UPF_HARD_FLOW) {
+	if (termios->c_cflag & CRTSCTS && up->port.flags & UPF_HARD_FLOW &&
+	    up->gpios == 0) {
 		/* Enable AUTOCTS (autoRTS is enabled when RTS is raised) */
 		up->port.status |= UPSTAT_AUTOCTS | UPSTAT_AUTORTS;
 		priv->efr |= UART_EFR_CTS;
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 2304a84eee3b..b86a16e2c9b6 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1662,6 +1662,8 @@ static void serial8250_disable_ms(struct uart_port *port)
 	if (up->bugs & UART_BUG_NOMSR)
 		return;
 
+	mctrl_gpio_disable_ms(up->gpios);
+
 	up->ier &= ~UART_IER_MSI;
 	serial_port_out(port, UART_IER, up->ier);
 }
@@ -1674,6 +1676,8 @@ static void serial8250_enable_ms(struct uart_port *port)
 	if (up->bugs & UART_BUG_NOMSR)
 		return;
 
+	mctrl_gpio_enable_ms(up->gpios);
+
 	up->ier |= UART_IER_MSI;
 
 	serial8250_rpm_get(up);
@@ -1951,6 +1955,9 @@ unsigned int serial8250_do_get_mctrl(struct uart_port *port)
 	serial8250_rpm_put(up);
 
 	ret = 0;
+	if (up->gpios)
+		return mctrl_gpio_get(up->gpios, &ret);
+
 	if (status & UART_MSR_DCD)
 		ret |= TIOCM_CAR;
 	if (status & UART_MSR_RI)
diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index 296115f6a4d8..509f6a3bb9ff 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -8,6 +8,7 @@ config SERIAL_8250
 	tristate "8250/16550 and compatible serial support"
 	depends on !S390
 	select SERIAL_CORE
+	select SERIAL_MCTRL_GPIO if GPIOLIB
 	---help---
 	  This selects whether you want to include the driver for the standard
 	  serial ports.  The standard answer is Y.  People who might say N
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index 5e0b59422a68..bb2bc99388ca 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -110,6 +110,7 @@ struct uart_8250_port {
 						 *   if no_console_suspend
 						 */
 	unsigned char		probe;
+	struct mctrl_gpios	*gpios;
 #define UART_PROBE_RSA	(1 << 0)
 
 	/*
-- 
2.22.0


^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers
  2019-06-11 10:56 ` [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers Stefan Roese
@ 2019-06-11 12:44   ` Andy Shevchenko
  2019-06-11 14:02     ` Stefan Roese
  2019-06-18  7:49   ` Greg Kroah-Hartman
  1 sibling, 1 reply; 10+ messages in thread
From: Andy Shevchenko @ 2019-06-11 12:44 UTC (permalink / raw)
  To: Stefan Roese
  Cc: linux-serial, linux-kernel, Yegor Yefremov, Mika Westerberg,
	Giulio Benetti, Greg Kroah-Hartman

On Tue, Jun 11, 2019 at 12:56:03PM +0200, Stefan Roese wrote:
> From: Yegor Yefremov <yegorslists@googlemail.com>
> 
> This patch permits the usage for GPIOs to control
> the CTS/RTS/DTR/DSR/DCD/RI signals.

>  static inline void serial8250_out_MCR(struct uart_8250_port *up, int value)
>  {
>  	serial_out(up, UART_MCR, value);
> +
> +	if (up->gpios) {
> +		int mctrl_gpio = 0;
> +
> +		if (value & UART_MCR_RTS)
> +			mctrl_gpio |= TIOCM_RTS;
> +		if (value & UART_MCR_DTR)
> +			mctrl_gpio |= TIOCM_DTR;
> +
> +		mctrl_gpio_set(up->gpios, mctrl_gpio);
> +	}
>  }
>  
>  static inline int serial8250_in_MCR(struct uart_8250_port *up)
>  {
> -	return serial_in(up, UART_MCR);
> +	int mctrl;
> +
> +	mctrl = serial_in(up, UART_MCR);
> +
> +	if (up->gpios) {
> +		int mctrl_gpio = 0;
> +
> +		/* save current MCR values */
> +		if (mctrl & UART_MCR_RTS)
> +			mctrl_gpio |= TIOCM_RTS;
> +		if (mctrl & UART_MCR_DTR)
> +			mctrl_gpio |= TIOCM_DTR;
> +
> +		mctrl_gpio = mctrl_gpio_get_outputs(up->gpios, &mctrl_gpio);
> +		if (mctrl_gpio & TIOCM_RTS)
> +			mctrl |= UART_MCR_RTS;
> +		else
> +			mctrl &= ~UART_MCR_RTS;
> +
> +		if (mctrl_gpio & TIOCM_DTR)
> +			mctrl |= UART_MCR_DTR;
> +		else
> +			mctrl &= ~UART_MCR_DTR;
> +	}
> +
> +	return mctrl;
>  }

These are using OR logic with potentially volatile data. Shouldn't we mask
unused bits in UART_MCR in case of up->gpios != NULL?

> +	if (up->gpios == 0)

This is type inconsistency with this check as far as I understand.
I guess you have to do either (up->gpios == NULL), or (!up->gpios).

>  	ret = 0;

+ Blank line.

> +	if (up->gpios)
> +		return mctrl_gpio_get(up->gpios, &ret);

-- 
With Best Regards,
Andy Shevchenko



^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers
  2019-06-11 12:44   ` Andy Shevchenko
@ 2019-06-11 14:02     ` Stefan Roese
  2019-06-11 14:48       ` Andy Shevchenko
  0 siblings, 1 reply; 10+ messages in thread
From: Stefan Roese @ 2019-06-11 14:02 UTC (permalink / raw)
  To: Andy Shevchenko
  Cc: linux-serial, linux-kernel, Yegor Yefremov, Mika Westerberg,
	Giulio Benetti, Greg Kroah-Hartman

On 11.06.19 14:44, Andy Shevchenko wrote:
> On Tue, Jun 11, 2019 at 12:56:03PM +0200, Stefan Roese wrote:
>> From: Yegor Yefremov <yegorslists@googlemail.com>
>>
>> This patch permits the usage for GPIOs to control
>> the CTS/RTS/DTR/DSR/DCD/RI signals.
> 
>>   static inline void serial8250_out_MCR(struct uart_8250_port *up, int value)
>>   {
>>   	serial_out(up, UART_MCR, value);
>> +
>> +	if (up->gpios) {
>> +		int mctrl_gpio = 0;
>> +
>> +		if (value & UART_MCR_RTS)
>> +			mctrl_gpio |= TIOCM_RTS;
>> +		if (value & UART_MCR_DTR)
>> +			mctrl_gpio |= TIOCM_DTR;
>> +
>> +		mctrl_gpio_set(up->gpios, mctrl_gpio);
>> +	}
>>   }
>>   
>>   static inline int serial8250_in_MCR(struct uart_8250_port *up)
>>   {
>> -	return serial_in(up, UART_MCR);
>> +	int mctrl;
>> +
>> +	mctrl = serial_in(up, UART_MCR);
>> +
>> +	if (up->gpios) {
>> +		int mctrl_gpio = 0;
>> +
>> +		/* save current MCR values */
>> +		if (mctrl & UART_MCR_RTS)
>> +			mctrl_gpio |= TIOCM_RTS;
>> +		if (mctrl & UART_MCR_DTR)
>> +			mctrl_gpio |= TIOCM_DTR;
>> +
>> +		mctrl_gpio = mctrl_gpio_get_outputs(up->gpios, &mctrl_gpio);
>> +		if (mctrl_gpio & TIOCM_RTS)
>> +			mctrl |= UART_MCR_RTS;
>> +		else
>> +			mctrl &= ~UART_MCR_RTS;
>> +
>> +		if (mctrl_gpio & TIOCM_DTR)
>> +			mctrl |= UART_MCR_DTR;
>> +		else
>> +			mctrl &= ~UART_MCR_DTR;
>> +	}
>> +
>> +	return mctrl;
>>   }
> 
> These are using OR logic with potentially volatile data. Shouldn't we mask
> unused bits in UART_MCR in case of up->gpios != NULL?

Sorry, I don't see, which bits you are referring to? Could you please be
a bit more specific with the variable / macro meant (example)?
  
>> +	if (up->gpios == 0)
> 
> This is type inconsistency with this check as far as I understand.
> I guess you have to do either (up->gpios == NULL), or (!up->gpios).

Ah, right. Thanks for spotting.

Thanks,
Stefan

^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers
  2019-06-11 14:02     ` Stefan Roese
@ 2019-06-11 14:48       ` Andy Shevchenko
  2019-06-12  8:13         ` Stefan Roese
  0 siblings, 1 reply; 10+ messages in thread
From: Andy Shevchenko @ 2019-06-11 14:48 UTC (permalink / raw)
  To: Stefan Roese
  Cc: linux-serial, linux-kernel, Yegor Yefremov, Mika Westerberg,
	Giulio Benetti, Greg Kroah-Hartman

On Tue, Jun 11, 2019 at 04:02:54PM +0200, Stefan Roese wrote:
> On 11.06.19 14:44, Andy Shevchenko wrote:
> > On Tue, Jun 11, 2019 at 12:56:03PM +0200, Stefan Roese wrote:

> > >   static inline void serial8250_out_MCR(struct uart_8250_port *up, int value)
> > >   {
> > >   	serial_out(up, UART_MCR, value);
> > > +
> > > +	if (up->gpios) {
> > > +		int mctrl_gpio = 0;
> > > +
> > > +		if (value & UART_MCR_RTS)
> > > +			mctrl_gpio |= TIOCM_RTS;
> > > +		if (value & UART_MCR_DTR)
> > > +			mctrl_gpio |= TIOCM_DTR;
> > > +
> > > +		mctrl_gpio_set(up->gpios, mctrl_gpio);
> > > +	}
> > >   }

> > >   static inline int serial8250_in_MCR(struct uart_8250_port *up)
> > >   {
> > > -	return serial_in(up, UART_MCR);
> > > +	int mctrl;
> > > +
> > > +	mctrl = serial_in(up, UART_MCR);
> > > +
> > > +	if (up->gpios) {
> > > +		int mctrl_gpio = 0;
> > > +
> > > +		/* save current MCR values */
> > > +		if (mctrl & UART_MCR_RTS)
> > > +			mctrl_gpio |= TIOCM_RTS;
> > > +		if (mctrl & UART_MCR_DTR)
> > > +			mctrl_gpio |= TIOCM_DTR;
> > > +
> > > +		mctrl_gpio = mctrl_gpio_get_outputs(up->gpios, &mctrl_gpio);
> > > +		if (mctrl_gpio & TIOCM_RTS)
> > > +			mctrl |= UART_MCR_RTS;
> > > +		else
> > > +			mctrl &= ~UART_MCR_RTS;
> > > +
> > > +		if (mctrl_gpio & TIOCM_DTR)
> > > +			mctrl |= UART_MCR_DTR;
> > > +		else
> > > +			mctrl &= ~UART_MCR_DTR;
> > > +	}
> > > +
> > > +	return mctrl;
> > >   }
> > 
> > These are using OR logic with potentially volatile data. Shouldn't we mask
> > unused bits in UART_MCR in case of up->gpios != NULL?
> 
> Sorry, I don't see, which bits you are referring to? Could you please be
> a bit more specific with the variable / macro meant (example)?

I meant that we double write values in the out() which might have some
consequences, though I hope nothing wrong with it happens.

In the in() we read the all bits in the register.

As now I look at the implementation of mctrl_gpio_get_outputs(),
I think we rather get helpers for conversion between TIOCM and UART_MCR values,
so, they can be used in get_mctrl() / set_mctrl() and above.

The logic now is understandable to me (I was confused by the conversions here
and there).

-- 
With Best Regards,
Andy Shevchenko



^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers
  2019-06-11 14:48       ` Andy Shevchenko
@ 2019-06-12  8:13         ` Stefan Roese
  2019-06-12  9:16           ` Andy Shevchenko
  0 siblings, 1 reply; 10+ messages in thread
From: Stefan Roese @ 2019-06-12  8:13 UTC (permalink / raw)
  To: Andy Shevchenko
  Cc: linux-serial, linux-kernel, Yegor Yefremov, Mika Westerberg,
	Giulio Benetti, Greg Kroah-Hartman

On 11.06.19 16:48, Andy Shevchenko wrote:
> On Tue, Jun 11, 2019 at 04:02:54PM +0200, Stefan Roese wrote:
>> On 11.06.19 14:44, Andy Shevchenko wrote:
>>> On Tue, Jun 11, 2019 at 12:56:03PM +0200, Stefan Roese wrote:
> 
>>>>    static inline void serial8250_out_MCR(struct uart_8250_port *up, int value)
>>>>    {
>>>>    	serial_out(up, UART_MCR, value);
>>>> +
>>>> +	if (up->gpios) {
>>>> +		int mctrl_gpio = 0;
>>>> +
>>>> +		if (value & UART_MCR_RTS)
>>>> +			mctrl_gpio |= TIOCM_RTS;
>>>> +		if (value & UART_MCR_DTR)
>>>> +			mctrl_gpio |= TIOCM_DTR;
>>>> +
>>>> +		mctrl_gpio_set(up->gpios, mctrl_gpio);
>>>> +	}
>>>>    }
> 
>>>>    static inline int serial8250_in_MCR(struct uart_8250_port *up)
>>>>    {
>>>> -	return serial_in(up, UART_MCR);
>>>> +	int mctrl;
>>>> +
>>>> +	mctrl = serial_in(up, UART_MCR);
>>>> +
>>>> +	if (up->gpios) {
>>>> +		int mctrl_gpio = 0;
>>>> +
>>>> +		/* save current MCR values */
>>>> +		if (mctrl & UART_MCR_RTS)
>>>> +			mctrl_gpio |= TIOCM_RTS;
>>>> +		if (mctrl & UART_MCR_DTR)
>>>> +			mctrl_gpio |= TIOCM_DTR;
>>>> +
>>>> +		mctrl_gpio = mctrl_gpio_get_outputs(up->gpios, &mctrl_gpio);
>>>> +		if (mctrl_gpio & TIOCM_RTS)
>>>> +			mctrl |= UART_MCR_RTS;
>>>> +		else
>>>> +			mctrl &= ~UART_MCR_RTS;
>>>> +
>>>> +		if (mctrl_gpio & TIOCM_DTR)
>>>> +			mctrl |= UART_MCR_DTR;
>>>> +		else
>>>> +			mctrl &= ~UART_MCR_DTR;
>>>> +	}
>>>> +
>>>> +	return mctrl;
>>>>    }
>>>
>>> These are using OR logic with potentially volatile data. Shouldn't we mask
>>> unused bits in UART_MCR in case of up->gpios != NULL?
>>
>> Sorry, I don't see, which bits you are referring to? Could you please be
>> a bit more specific with the variable / macro meant (example)?
> 
> I meant that we double write values in the out() which might have some
> consequences, though I hope nothing wrong with it happens.

Where is the double write to a register? Sorry, I fail to spot it.
  
> In the in() we read the all bits in the register.
> 
> As now I look at the implementation of mctrl_gpio_get_outputs(),
> I think we rather get helpers for conversion between TIOCM and UART_MCR values,
> so, they can be used in get_mctrl() / set_mctrl() and above.

Do you something like this in mind?

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index dc9354e34b60..f44561fcb941 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1954,19 +1954,12 @@ unsigned int serial8250_do_get_mctrl(struct uart_port *port)
         status = serial8250_modem_status(up);
         serial8250_rpm_put(up);
  
-       ret = 0;
-
         if (up->gpios)
                 return mctrl_gpio_get(up->gpios, &ret);
  
-       if (status & UART_MSR_DCD)
-               ret |= TIOCM_CAR;
-       if (status & UART_MSR_RI)
-               ret |= TIOCM_RNG;
-       if (status & UART_MSR_DSR)
-               ret |= TIOCM_DSR;
-       if (status & UART_MSR_CTS)
-               ret |= TIOCM_CTS;
+       ret = UART_MSR_TO_TIOCM_DCD(status) | UART_MSR_TO_TIOCM_RI(status) |
+               UART_MSR_TO_TIOCM_DSR(status) | UART_MSR_TO_TIOCM_CTS(status);
+
         return ret;
  }
  EXPORT_SYMBOL_GPL(serial8250_do_get_mctrl);
@@ -1983,16 +1976,9 @@ void serial8250_do_set_mctrl(struct uart_port *port, unsigned int mctrl)
         struct uart_8250_port *up = up_to_u8250p(port);
         unsigned char mcr = 0;
  
-       if (mctrl & TIOCM_RTS)
-               mcr |= UART_MCR_RTS;
-       if (mctrl & TIOCM_DTR)
-               mcr |= UART_MCR_DTR;
-       if (mctrl & TIOCM_OUT1)
-               mcr |= UART_MCR_OUT1;
-       if (mctrl & TIOCM_OUT2)
-               mcr |= UART_MCR_OUT2;
-       if (mctrl & TIOCM_LOOP)
-               mcr |= UART_MCR_LOOP;
+       mcr = TIOCM_TO_UART_MCR_RTS(mctrl) | TIOCM_TO_UART_MCR_DTR(mctrl) |
+               TIOCM_TO_UART_MCR_OUT1(mctrl) | TIOCM_TO_UART_MCR_OUT2(mctrl) |
+               TIOCM_TO_UART_MCR_LOOP(mctrl);
  
         mcr = (mcr & up->mcr_mask) | up->mcr_force | up->mcr;
  
diff --git a/include/uapi/linux/serial_reg.h b/include/uapi/linux/serial_reg.h
index be07b5470f4b..bda905a1b765 100644
--- a/include/uapi/linux/serial_reg.h
+++ b/include/uapi/linux/serial_reg.h
@@ -376,5 +376,22 @@
  #define UART_ALTR_EN_TXFIFO_LW 0x01    /* Enable the TX FIFO Low Watermark */
  #define UART_ALTR_TX_LOW       0x41    /* Tx FIFO Low Watermark */
  
+#define UART_MSR_TO_TIOCM_DCD(val)     ((val & UART_MSR_DCD) ? TIOCM_CAR : 0)
+#define UART_MSR_TO_TIOCM_RI(val)      ((val & UART_MSR_RI) ? TIOCM_RNG : 0)
+#define UART_MSR_TO_TIOCM_DSR(val)     ((val & UART_MSR_DSR) ? TIOCM_DSR : 0)
+#define UART_MSR_TO_TIOCM_CTS(val)     ((val & UART_MSR_CTS) ? TIOCM_CTS : 0)
+#define UART_MSR_TO_TIOCM_RTS(val)     ((val & UART_MSR_RTS) ? TIOCM_RTS : 0)
+#define UART_MSR_TO_TIOCM_DTR(val)     ((val & UART_MSR_DTR) ? TIOCM_DTR : 0)
+
+#define TIOCM_TO_UART_MCR_DCD(val)     ((val & TIOCM_DCD) ? UART_MCR_CAR : 0)
+#define TIOCM_TO_UART_MCR_RI(val)      ((val & TIOCM_RI) ? UART_MCR_RNG : 0)
+#define TIOCM_TO_UART_MCR_DSR(val)     ((val & TIOCM_DSR) ? UART_MCR_DSR : 0)
+#define TIOCM_TO_UART_MCR_CTS(val)     ((val & TIOCM_CTS) ? UART_MCR_CTS : 0)
+#define TIOCM_TO_UART_MCR_RTS(val)     ((val & TIOCM_RTS) ? UART_MCR_RTS : 0)
+#define TIOCM_TO_UART_MCR_DTR(val)     ((val & TIOCM_DTR) ? UART_MCR_DTR : 0)
+#define TIOCM_TO_UART_MCR_LOOP(val)    ((val & TIOCM_LOOP) ? UART_MCR_LOOP : 0)
+#define TIOCM_TO_UART_MCR_OUT1(val)    ((val & TIOCM_OUT1) ? UART_MCR_OUT1 : 0)
+#define TIOCM_TO_UART_MCR_OUT2(val)    ((val & TIOCM_OUT2) ? UART_MCR_OUT2 : 0)
+
  #endif /* _LINUX_SERIAL_REG_H */


Plus the use of these macros in this patch of course.

If yes, then I'll add a new patch (pretty similar to the one included
above) to this series.

Thanks,
Stefan

^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers
  2019-06-12  8:13         ` Stefan Roese
@ 2019-06-12  9:16           ` Andy Shevchenko
  2019-06-13  5:32             ` Stefan Roese
  0 siblings, 1 reply; 10+ messages in thread
From: Andy Shevchenko @ 2019-06-12  9:16 UTC (permalink / raw)
  To: Stefan Roese
  Cc: linux-serial, linux-kernel, Yegor Yefremov, Mika Westerberg,
	Giulio Benetti, Greg Kroah-Hartman

On Wed, Jun 12, 2019 at 10:13:05AM +0200, Stefan Roese wrote:
> On 11.06.19 16:48, Andy Shevchenko wrote:
> > On Tue, Jun 11, 2019 at 04:02:54PM +0200, Stefan Roese wrote:
> > > On 11.06.19 14:44, Andy Shevchenko wrote:
> > > > On Tue, Jun 11, 2019 at 12:56:03PM +0200, Stefan Roese wrote:
> > 
> > > > >    static inline void serial8250_out_MCR(struct uart_8250_port *up, int value)
> > > > >    {
> > > > >    	serial_out(up, UART_MCR, value);
> > > > > +
> > > > > +	if (up->gpios) {
> > > > > +		int mctrl_gpio = 0;
> > > > > +
> > > > > +		if (value & UART_MCR_RTS)
> > > > > +			mctrl_gpio |= TIOCM_RTS;
> > > > > +		if (value & UART_MCR_DTR)
> > > > > +			mctrl_gpio |= TIOCM_DTR;
> > > > > +
> > > > > +		mctrl_gpio_set(up->gpios, mctrl_gpio);
> > > > > +	}
> > > > >    }
> > 
> > > > >    static inline int serial8250_in_MCR(struct uart_8250_port *up)
> > > > >    {
> > > > > -	return serial_in(up, UART_MCR);
> > > > > +	int mctrl;
> > > > > +
> > > > > +	mctrl = serial_in(up, UART_MCR);
> > > > > +
> > > > > +	if (up->gpios) {
> > > > > +		int mctrl_gpio = 0;
> > > > > +
> > > > > +		/* save current MCR values */
> > > > > +		if (mctrl & UART_MCR_RTS)
> > > > > +			mctrl_gpio |= TIOCM_RTS;
> > > > > +		if (mctrl & UART_MCR_DTR)
> > > > > +			mctrl_gpio |= TIOCM_DTR;
> > > > > +
> > > > > +		mctrl_gpio = mctrl_gpio_get_outputs(up->gpios, &mctrl_gpio);
> > > > > +		if (mctrl_gpio & TIOCM_RTS)
> > > > > +			mctrl |= UART_MCR_RTS;
> > > > > +		else
> > > > > +			mctrl &= ~UART_MCR_RTS;
> > > > > +
> > > > > +		if (mctrl_gpio & TIOCM_DTR)
> > > > > +			mctrl |= UART_MCR_DTR;
> > > > > +		else
> > > > > +			mctrl &= ~UART_MCR_DTR;
> > > > > +	}
> > > > > +
> > > > > +	return mctrl;
> > > > >    }
> > > > 
> > > > These are using OR logic with potentially volatile data. Shouldn't we mask
> > > > unused bits in UART_MCR in case of up->gpios != NULL?
> > > 
> > > Sorry, I don't see, which bits you are referring to? Could you please be
> > > a bit more specific with the variable / macro meant (example)?
> > 
> > I meant that we double write values in the out() which might have some
> > consequences, though I hope nothing wrong with it happens.
> 
> Where is the double write to a register? Sorry, I fail to spot it.

Not to the one register. From the functional point of view the same signal is
set up twice: once per UART register, once per GPIO pins.

> > In the in() we read the all bits in the register.
> > 
> > As now I look at the implementation of mctrl_gpio_get_outputs(),
> > I think we rather get helpers for conversion between TIOCM and UART_MCR values,
> > so, they can be used in get_mctrl() / set_mctrl() and above.
> 
> Do you something like this in mind?

More likely

static inline int serial8250_MCR_to_TIOCM(int mcr)
{
	int tiocm = 0;

	if (mcr & ...)
		tiocm |= ...;
	...

	return tiocm;
}

static inline int serial8250_TIOCM_to_MCR(int tiocm)
{
	... in a similar way ...
}

> Plus the use of these macros in this patch of course.

No macros, please.

-- 
With Best Regards,
Andy Shevchenko



^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers
  2019-06-12  9:16           ` Andy Shevchenko
@ 2019-06-13  5:32             ` Stefan Roese
  2019-06-13 11:05               ` Andy Shevchenko
  0 siblings, 1 reply; 10+ messages in thread
From: Stefan Roese @ 2019-06-13  5:32 UTC (permalink / raw)
  To: Andy Shevchenko
  Cc: linux-serial, linux-kernel, Yegor Yefremov, Mika Westerberg,
	Giulio Benetti, Greg Kroah-Hartman

On 12.06.19 11:16, Andy Shevchenko wrote:
> On Wed, Jun 12, 2019 at 10:13:05AM +0200, Stefan Roese wrote:
>> On 11.06.19 16:48, Andy Shevchenko wrote:
>>> On Tue, Jun 11, 2019 at 04:02:54PM +0200, Stefan Roese wrote:
>>>> On 11.06.19 14:44, Andy Shevchenko wrote:
>>>>> On Tue, Jun 11, 2019 at 12:56:03PM +0200, Stefan Roese wrote:
>>>
>>>>>>     static inline void serial8250_out_MCR(struct uart_8250_port *up, int value)
>>>>>>     {
>>>>>>     	serial_out(up, UART_MCR, value);
>>>>>> +
>>>>>> +	if (up->gpios) {
>>>>>> +		int mctrl_gpio = 0;
>>>>>> +
>>>>>> +		if (value & UART_MCR_RTS)
>>>>>> +			mctrl_gpio |= TIOCM_RTS;
>>>>>> +		if (value & UART_MCR_DTR)
>>>>>> +			mctrl_gpio |= TIOCM_DTR;
>>>>>> +
>>>>>> +		mctrl_gpio_set(up->gpios, mctrl_gpio);
>>>>>> +	}
>>>>>>     }
>>>
>>>>>>     static inline int serial8250_in_MCR(struct uart_8250_port *up)
>>>>>>     {
>>>>>> -	return serial_in(up, UART_MCR);
>>>>>> +	int mctrl;
>>>>>> +
>>>>>> +	mctrl = serial_in(up, UART_MCR);
>>>>>> +
>>>>>> +	if (up->gpios) {
>>>>>> +		int mctrl_gpio = 0;
>>>>>> +
>>>>>> +		/* save current MCR values */
>>>>>> +		if (mctrl & UART_MCR_RTS)
>>>>>> +			mctrl_gpio |= TIOCM_RTS;
>>>>>> +		if (mctrl & UART_MCR_DTR)
>>>>>> +			mctrl_gpio |= TIOCM_DTR;
>>>>>> +
>>>>>> +		mctrl_gpio = mctrl_gpio_get_outputs(up->gpios, &mctrl_gpio);
>>>>>> +		if (mctrl_gpio & TIOCM_RTS)
>>>>>> +			mctrl |= UART_MCR_RTS;
>>>>>> +		else
>>>>>> +			mctrl &= ~UART_MCR_RTS;
>>>>>> +
>>>>>> +		if (mctrl_gpio & TIOCM_DTR)
>>>>>> +			mctrl |= UART_MCR_DTR;
>>>>>> +		else
>>>>>> +			mctrl &= ~UART_MCR_DTR;
>>>>>> +	}
>>>>>> +
>>>>>> +	return mctrl;
>>>>>>     }
>>>>>
>>>>> These are using OR logic with potentially volatile data. Shouldn't we mask
>>>>> unused bits in UART_MCR in case of up->gpios != NULL?
>>>>
>>>> Sorry, I don't see, which bits you are referring to? Could you please be
>>>> a bit more specific with the variable / macro meant (example)?
>>>
>>> I meant that we double write values in the out() which might have some
>>> consequences, though I hope nothing wrong with it happens.
>>
>> Where is the double write to a register? Sorry, I fail to spot it.
> 
> Not to the one register. From the functional point of view the same signal is
> set up twice: once per UART register, once per GPIO pins.
> 
>>> In the in() we read the all bits in the register.
>>>
>>> As now I look at the implementation of mctrl_gpio_get_outputs(),
>>> I think we rather get helpers for conversion between TIOCM and UART_MCR values,
>>> so, they can be used in get_mctrl() / set_mctrl() and above.
>>
>> Do you something like this in mind?
> 
> More likely
> 
> static inline int serial8250_MCR_to_TIOCM(int mcr)

MSR_to_TIOCM (see below) ...

> {
> 	int tiocm = 0;
> 
> 	if (mcr & ...)
> 		tiocm |= ...;
> 	...
> 
> 	return tiocm;
> }
> 
> static inline int serial8250_TIOCM_to_MCR(int tiocm)
> {
> 	... in a similar way ...
> }

While implementing such wrapper functions I noticed, that get_mctrl() /
set_mctrl() need TIOCM->MCR and MSR->TIOCM (notice MSR vs MCR here) but
serial8250_in_MCR() needs MCR->TIOCM. So there is not that much
overlay here. Additionally the wrappers would need to handle all bits
and only some of them are needed in serial8250_in/out_MCR(), so I would
need to add masking here as well.

For my taste its not really worth adding these wrappers as they won't
make things much clearer (if at all).

Thanks,
Stefan

^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers
  2019-06-13  5:32             ` Stefan Roese
@ 2019-06-13 11:05               ` Andy Shevchenko
  0 siblings, 0 replies; 10+ messages in thread
From: Andy Shevchenko @ 2019-06-13 11:05 UTC (permalink / raw)
  To: Stefan Roese
  Cc: linux-serial, linux-kernel, Yegor Yefremov, Mika Westerberg,
	Giulio Benetti, Greg Kroah-Hartman

On Thu, Jun 13, 2019 at 07:32:39AM +0200, Stefan Roese wrote:
> On 12.06.19 11:16, Andy Shevchenko wrote:
> > On Wed, Jun 12, 2019 at 10:13:05AM +0200, Stefan Roese wrote:
> > > On 11.06.19 16:48, Andy Shevchenko wrote:

> > > Do you something like this in mind?
> > 
> > More likely
> > 
> > static inline int serial8250_MCR_to_TIOCM(int mcr)
> 
> MSR_to_TIOCM (see below) ...

Yes. true.

> > {
> > 	int tiocm = 0;
> > 
> > 	if (mcr & ...)
> > 		tiocm |= ...;
> > 	...
> > 
> > 	return tiocm;
> > }
> > 
> > static inline int serial8250_TIOCM_to_MCR(int tiocm)
> > {
> > 	... in a similar way ...
> > }
> 
> While implementing such wrapper functions I noticed, that get_mctrl() /
> set_mctrl() need TIOCM->MCR and MSR->TIOCM (notice MSR vs MCR here) but
> serial8250_in_MCR() needs MCR->TIOCM. So there is not that much
> overlay here.

It seems not only this driver is using such conversion. It's even possible to
move it to serial level for all.

> Additionally the wrappers would need to handle all bits
> and only some of them are needed in serial8250_in/out_MCR(),
> so I would
> need to add masking here as well.

I don't see this. You will get a value for exclusive bits only. No additional
mask would be needed.

> For my taste its not really worth adding these wrappers as they won't
> make things much clearer (if at all).

Hmm.. For me it would be quite clear if something with proposed name would be
called in the code.

-- 
With Best Regards,
Andy Shevchenko



^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers
  2019-06-11 10:56 ` [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers Stefan Roese
  2019-06-11 12:44   ` Andy Shevchenko
@ 2019-06-18  7:49   ` Greg Kroah-Hartman
  1 sibling, 0 replies; 10+ messages in thread
From: Greg Kroah-Hartman @ 2019-06-18  7:49 UTC (permalink / raw)
  To: Stefan Roese
  Cc: linux-serial, linux-kernel, Yegor Yefremov, Mika Westerberg,
	Andy Shevchenko, Giulio Benetti

On Tue, Jun 11, 2019 at 12:56:03PM +0200, Stefan Roese wrote:
> From: Yegor Yefremov <yegorslists@googlemail.com>
> 
> This patch permits the usage for GPIOs to control
> the CTS/RTS/DTR/DSR/DCD/RI signals.
> 
> Changed by Stefan:
> Only call mctrl_gpio_init(), if the device has no ACPI companion device
> to not break existing ACPI based systems. Also only use the mctrl_gpio_
> functions when "gpios" is available.
> 
> Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Please do not add a signed-off-by from people for an old patch that was
reverted.  It implies that I still agree with this change :(

greg k-h

^ permalink raw reply	[flat|nested] 10+ messages in thread

end of thread, other threads:[~2019-06-18  7:49 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-06-11 10:56 [PATCH 1/2 v5] serial: mctrl_gpio: Check if GPIO property exisits before requesting it Stefan Roese
2019-06-11 10:56 ` [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers Stefan Roese
2019-06-11 12:44   ` Andy Shevchenko
2019-06-11 14:02     ` Stefan Roese
2019-06-11 14:48       ` Andy Shevchenko
2019-06-12  8:13         ` Stefan Roese
2019-06-12  9:16           ` Andy Shevchenko
2019-06-13  5:32             ` Stefan Roese
2019-06-13 11:05               ` Andy Shevchenko
2019-06-18  7:49   ` Greg Kroah-Hartman

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