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* [PATCH net-next v3] net: phy: intel-xway: Add RGMII internal delay configuration
@ 2021-07-09 16:42 Martin Schiller
  2021-07-09 18:31 ` Martin Blumenstingl
  0 siblings, 1 reply; 6+ messages in thread
From: Martin Schiller @ 2021-07-09 16:42 UTC (permalink / raw)
  To: hauke, martin.blumenstingl, f.fainelli, andrew, hkallweit1,
	linux, davem, kuba
  Cc: netdev, linux-kernel, Martin Schiller

This adds the posibility to configure the RGMII RX/TX clock skew via
devicetree.

Simply set phy mode to "rgmii-id", "rgmii-rxid" or "rgmii-txid" and add
the "rx-internal-delay-ps" or "tx-internal-delay-ps" property to the
devicetree.

Furthermore, a warning is now issued if the phy mode is configured to
"rgmii" and an internal delay is set in the phy (e.g. by pin-strapping),
as in the dp83867 driver.

Signed-off-by: Martin Schiller <ms@dev.tdt.de>
---

Changes to v2:
o Fix missing whitespace in warning.

Changes to v1:
o code cleanup and use phy_modify().
o use default of 2.0ns if delay property is absent instead of returning
  an error.

---
 drivers/net/phy/intel-xway.c | 90 ++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)

diff --git a/drivers/net/phy/intel-xway.c b/drivers/net/phy/intel-xway.c
index d453ec016168..796e6f2eb2d5 100644
--- a/drivers/net/phy/intel-xway.c
+++ b/drivers/net/phy/intel-xway.c
@@ -9,10 +9,16 @@
 #include <linux/phy.h>
 #include <linux/of.h>
 
+#define XWAY_MDIO_MIICTRL		0x17	/* mii control */
 #define XWAY_MDIO_IMASK			0x19	/* interrupt mask */
 #define XWAY_MDIO_ISTAT			0x1A	/* interrupt status */
 #define XWAY_MDIO_LED			0x1B	/* led control */
 
+#define XWAY_MDIO_MIICTRL_RXSKEW_MASK	GENMASK(14, 12)
+#define XWAY_MDIO_MIICTRL_RXSKEW_SHIFT	12
+#define XWAY_MDIO_MIICTRL_TXSKEW_MASK	GENMASK(10, 8)
+#define XWAY_MDIO_MIICTRL_TXSKEW_SHIFT	8
+
 /* bit 15:12 are reserved */
 #define XWAY_MDIO_LED_LED3_EN		BIT(11)	/* Enable the integrated function of LED3 */
 #define XWAY_MDIO_LED_LED2_EN		BIT(10)	/* Enable the integrated function of LED2 */
@@ -157,6 +163,86 @@
 #define PHY_ID_PHY11G_VR9_1_2		0xD565A409
 #define PHY_ID_PHY22F_VR9_1_2		0xD565A419
 
+#if IS_ENABLED(CONFIG_OF_MDIO)
+static const int xway_internal_delay[] = {0, 500, 1000, 1500, 2000, 2500,
+					 3000, 3500};
+
+static int xway_gphy_of_reg_init(struct phy_device *phydev)
+{
+	struct device *dev = &phydev->mdio.dev;
+	int delay_size = ARRAY_SIZE(xway_internal_delay);
+	s32 rx_int_delay;
+	s32 tx_int_delay;
+	u16 mask = 0;
+	int val = 0;
+
+	if (!phy_interface_is_rgmii(phydev))
+		return 0;
+
+	/* Existing behavior was to use default pin strapping delay in rgmii
+	 * mode, but rgmii should have meant no delay.  Warn existing users,
+	 * but do not change anything at the moment.
+	 */
+	if (phydev->interface == PHY_INTERFACE_MODE_RGMII) {
+		u16 txskew, rxskew;
+
+		val = phy_read(phydev, XWAY_MDIO_MIICTRL);
+		if (val < 0)
+			return val;
+
+		txskew = (val & XWAY_MDIO_MIICTRL_TXSKEW_MASK) >>
+			 XWAY_MDIO_MIICTRL_TXSKEW_SHIFT;
+		rxskew = (val & XWAY_MDIO_MIICTRL_RXSKEW_MASK) >>
+			 XWAY_MDIO_MIICTRL_RXSKEW_SHIFT;
+
+		if (txskew > 0 || rxskew > 0)
+			phydev_warn(phydev,
+				    "PHY has delays (e.g. via pin strapping), but phy-mode = 'rgmii'\n"
+				    "Should be 'rgmii-id' to use internal delays txskew:%d ps rxskew:%d ps\n",
+				    xway_internal_delay[txskew],
+				    xway_internal_delay[rxskew]);
+		return 0;
+	}
+
+	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
+	    phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID) {
+		rx_int_delay = phy_get_internal_delay(phydev, dev,
+						      &xway_internal_delay[0],
+						      delay_size, true);
+
+		if (rx_int_delay < 0) {
+			phydev_warn(phydev, "rx-internal-delay-ps is missing, use default of 2.0 ns\n");
+			rx_int_delay = 4; /* 2000 ps */
+		}
+
+		mask |= XWAY_MDIO_MIICTRL_RXSKEW_MASK;
+		val |= rx_int_delay << XWAY_MDIO_MIICTRL_RXSKEW_SHIFT;
+	}
+
+	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
+	    phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID) {
+		tx_int_delay = phy_get_internal_delay(phydev, dev,
+						      &xway_internal_delay[0],
+						      delay_size, false);
+
+		if (tx_int_delay < 0) {
+			phydev_warn(phydev, "tx-internal-delay-ps is missing, use default of 2.0 ns\n");
+			tx_int_delay = 4; /* 2000 ps */
+		}
+
+		mask |= XWAY_MDIO_MIICTRL_TXSKEW_MASK;
+		val |= tx_int_delay << XWAY_MDIO_MIICTRL_TXSKEW_SHIFT;
+	}
+
+	return phy_modify(phydev, XWAY_MDIO_MIICTRL, mask, val);
+}
+#else
+static int xway_gphy_of_reg_init(struct phy_device *phydev)
+{
+	return 0;
+}
+#endif /* CONFIG_OF_MDIO */
+
 static int xway_gphy_config_init(struct phy_device *phydev)
 {
 	int err;
@@ -204,6 +290,10 @@ static int xway_gphy_config_init(struct phy_device *phydev)
 	phy_write_mmd(phydev, MDIO_MMD_VEND2, XWAY_MMD_LED2H, ledxh);
 	phy_write_mmd(phydev, MDIO_MMD_VEND2, XWAY_MMD_LED2L, ledxl);
 
+	err = xway_gphy_of_reg_init(phydev);
+	if (err)
+		return err;
+
 	return 0;
 }
 
-- 
2.20.1


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH net-next v3] net: phy: intel-xway: Add RGMII internal delay configuration
  2021-07-09 16:42 [PATCH net-next v3] net: phy: intel-xway: Add RGMII internal delay configuration Martin Schiller
@ 2021-07-09 18:31 ` Martin Blumenstingl
  2021-07-12  6:13   ` Martin Schiller
  0 siblings, 1 reply; 6+ messages in thread
From: Martin Blumenstingl @ 2021-07-09 18:31 UTC (permalink / raw)
  To: Martin Schiller
  Cc: Hauke Mehrtens, f.fainelli, andrew, hkallweit1, linux, davem,
	kuba, netdev, linux-kernel

Hi Martin,

overall this is looking good.
A few comments below - I think none of them is a "must change" in my opinion.

On Fri, Jul 9, 2021 at 6:42 PM Martin Schiller <ms@dev.tdt.de> wrote:
>
> This adds the posibility to configure the RGMII RX/TX clock skew via
typo: posibility -> possibility

[...]
> +#define XWAY_MDIO_MIICTRL_RXSKEW_MASK  GENMASK(14, 12)
> +#define XWAY_MDIO_MIICTRL_RXSKEW_SHIFT 12
if you use
- FIELD_PREP(XWAY_MDIO_MIICTRL_RXSKEW_MASK, rxskew); (as for example [0] does)
- and FIELD_GET(XWAY_MDIO_MIICTRL_RXSKEW_MASK, val);
below then you can drop the _SHIFT #define
this is purely cosmetic though, so nothing which blocks this from being merged

> +#define XWAY_MDIO_MIICTRL_TXSKEW_MASK  GENMASK(10, 8)
> +#define XWAY_MDIO_MIICTRL_TXSKEW_SHIFT 8
same as above

[...]
> +#if IS_ENABLED(CONFIG_OF_MDIO)
is there any particular reason why we need to guard this with CONFIG_OF_MDIO?
The dp83822 driver does not use this #if either (as far as I
understand at least)

[...]
> +static int xway_gphy_of_reg_init(struct phy_device *phydev)
> +{
> +       struct device *dev = &phydev->mdio.dev;
> +       int delay_size = ARRAY_SIZE(xway_internal_delay);
Some people in the kernel community are working on automatically
detecting and fixing signedness issues.
I am not sure if they would find this at some point suggesting that it
can be an "unsigned int".

> +       s32 rx_int_delay;
> +       s32 tx_int_delay;
xway_gphy14_config_aneg() below defines two variables in one line, so
to be consistent this would be:
    s32 rx_int_delay, tx_int_delay;
another option is to just re-use one "int_delay" variable (as it seems
that they're both used in different code-paths).

> +       u16 mask = 0;
I think this should be dropped and the phy_modify() call below should read:
    return phy_modify(phydev, XWAY_MDIO_MIICTRL,
                                  XWAY_MDIO_MIICTRL_RXSKEW_MASK |
                                  XWAY_MDIO_MIICTRL_TXSKEW_MASK, val);
For rgmii-txid the RX delay might be provided by the MAC or PCB trace
length so the PHY should not add any RX delay.
Similarly for rgmii-rxid the TX delay might be provided by the MAC or
PCB trace length so the PHY should not add any TX delay.
That means we always need to mask the RX and TX skew bits, regardless
of what we're setting later on (as phy_modify is only called for one
of: rgmii-id, rgmii-txid, rgmii-rxid).

[...]
> +       if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> +           phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID) {
> +               rx_int_delay = phy_get_internal_delay(phydev, dev,
> +                                                     &xway_internal_delay[0],
I think above line can be simplified as:
    xway_internal_delay,

[...]
> +       if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> +           phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID) {
> +               tx_int_delay = phy_get_internal_delay(phydev, dev,
> +                                                     &xway_internal_delay[0],
same as above


Best regards,
Martin


[0] https://elixir.bootlin.com/linux/v5.13/source/drivers/net/phy/dp83867.c#L438

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH net-next v3] net: phy: intel-xway: Add RGMII internal delay configuration
  2021-07-09 18:31 ` Martin Blumenstingl
@ 2021-07-12  6:13   ` Martin Schiller
  2021-07-13 13:06     ` Andrew Lunn
  0 siblings, 1 reply; 6+ messages in thread
From: Martin Schiller @ 2021-07-12  6:13 UTC (permalink / raw)
  To: Martin Blumenstingl
  Cc: Hauke Mehrtens, f.fainelli, andrew, hkallweit1, linux, davem,
	kuba, netdev, linux-kernel

On 2021-07-09 20:31, Martin Blumenstingl wrote:
> Hi Martin,
> 
> overall this is looking good.
> A few comments below - I think none of them is a "must change" in my 
> opinion.
> 
> On Fri, Jul 9, 2021 at 6:42 PM Martin Schiller <ms@dev.tdt.de> wrote:
>> 
>> This adds the posibility to configure the RGMII RX/TX clock skew via
> typo: posibility -> possibility
> 

Thanks. I'll fix that.

> [...]
>> +#define XWAY_MDIO_MIICTRL_RXSKEW_MASK  GENMASK(14, 12)
>> +#define XWAY_MDIO_MIICTRL_RXSKEW_SHIFT 12
> if you use
> - FIELD_PREP(XWAY_MDIO_MIICTRL_RXSKEW_MASK, rxskew); (as for example 
> [0] does)
> - and FIELD_GET(XWAY_MDIO_MIICTRL_RXSKEW_MASK, val);
> below then you can drop the _SHIFT #define
> this is purely cosmetic though, so nothing which blocks this from being 
> merged
> 
>> +#define XWAY_MDIO_MIICTRL_TXSKEW_MASK  GENMASK(10, 8)
>> +#define XWAY_MDIO_MIICTRL_TXSKEW_SHIFT 8
> same as above
> 

Thanks for the hint. I'll switch to the FIELD_... macros.

> [...]
>> +#if IS_ENABLED(CONFIG_OF_MDIO)
> is there any particular reason why we need to guard this with 
> CONFIG_OF_MDIO?
> The dp83822 driver does not use this #if either (as far as I
> understand at least)
> 

It makes no sense to retrieve properties from the device tree if we are
compiling for a target that does not support a device tree.
At least that is my understanding of this condition.

> [...]
>> +static int xway_gphy_of_reg_init(struct phy_device *phydev)
>> +{
>> +       struct device *dev = &phydev->mdio.dev;
>> +       int delay_size = ARRAY_SIZE(xway_internal_delay);
> Some people in the kernel community are working on automatically
> detecting and fixing signedness issues.
> I am not sure if they would find this at some point suggesting that it
> can be an "unsigned int".
> 

OK, I'll change that.

>> +       s32 rx_int_delay;
>> +       s32 tx_int_delay;
> xway_gphy14_config_aneg() below defines two variables in one line, so
> to be consistent this would be:
>     s32 rx_int_delay, tx_int_delay;
> another option is to just re-use one "int_delay" variable (as it seems
> that they're both used in different code-paths).
> 

I'll switch to use one "int_delay".

>> +       u16 mask = 0;
> I think this should be dropped and the phy_modify() call below should 
> read:
>     return phy_modify(phydev, XWAY_MDIO_MIICTRL,
>                                   XWAY_MDIO_MIICTRL_RXSKEW_MASK |
>                                   XWAY_MDIO_MIICTRL_TXSKEW_MASK, val);
> For rgmii-txid the RX delay might be provided by the MAC or PCB trace
> length so the PHY should not add any RX delay.
> Similarly for rgmii-rxid the TX delay might be provided by the MAC or
> PCB trace length so the PHY should not add any TX delay.
> That means we always need to mask the RX and TX skew bits, regardless
> of what we're setting later on (as phy_modify is only called for one
> of: rgmii-id, rgmii-txid, rgmii-rxid).
> 

Yes, you are right. I'll change that as suggested.

> [...]
>> +       if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
>> +           phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID) {
>> +               rx_int_delay = phy_get_internal_delay(phydev, dev,
>> +                                                     
>> &xway_internal_delay[0],
> I think above line can be simplified as:
>     xway_internal_delay,

I've copied that from dp83869.c, but yes, I can change it.


> 
> [...]
>> +       if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
>> +           phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID) {
>> +               tx_int_delay = phy_get_internal_delay(phydev, dev,
>> +                                                     
>> &xway_internal_delay[0],
> same as above
> 

dito.

> 
> Best regards,
> Martin
> 
> 
> [0] 
> https://elixir.bootlin.com/linux/v5.13/source/drivers/net/phy/dp83867.c#L438

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH net-next v3] net: phy: intel-xway: Add RGMII internal delay configuration
  2021-07-12  6:13   ` Martin Schiller
@ 2021-07-13 13:06     ` Andrew Lunn
  2021-07-17 16:38       ` Hauke Mehrtens
  0 siblings, 1 reply; 6+ messages in thread
From: Andrew Lunn @ 2021-07-13 13:06 UTC (permalink / raw)
  To: Martin Schiller
  Cc: Martin Blumenstingl, Hauke Mehrtens, f.fainelli, hkallweit1,
	linux, davem, kuba, netdev, linux-kernel

> > [...]
> > > +#if IS_ENABLED(CONFIG_OF_MDIO)
> > is there any particular reason why we need to guard this with
> > CONFIG_OF_MDIO?
> > The dp83822 driver does not use this #if either (as far as I
> > understand at least)
> > 
> 
> It makes no sense to retrieve properties from the device tree if we are
> compiling for a target that does not support a device tree.
> At least that is my understanding of this condition.

There should be stubs for all these functions, so if OF is not part of
the configured kernel, stub functions take their place. That has the
advantage of at least compiling the code, so checking parameter types
etc. We try to avoid #ifdef where possible, so we get better compiler
build test coverage. The more #ifef there are, the more different
configurations that need compiling in order to get build coverage.

	       Andrew

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH net-next v3] net: phy: intel-xway: Add RGMII internal delay configuration
  2021-07-13 13:06     ` Andrew Lunn
@ 2021-07-17 16:38       ` Hauke Mehrtens
  2021-07-19  8:14         ` Martin Schiller
  0 siblings, 1 reply; 6+ messages in thread
From: Hauke Mehrtens @ 2021-07-17 16:38 UTC (permalink / raw)
  To: Andrew Lunn, Martin Schiller
  Cc: Martin Blumenstingl, f.fainelli, hkallweit1, linux, davem, kuba,
	netdev, linux-kernel

On 7/13/21 3:06 PM, Andrew Lunn wrote:
>>> [...]
>>>> +#if IS_ENABLED(CONFIG_OF_MDIO)
>>> is there any particular reason why we need to guard this with
>>> CONFIG_OF_MDIO?
>>> The dp83822 driver does not use this #if either (as far as I
>>> understand at least)
>>>
>>
>> It makes no sense to retrieve properties from the device tree if we are
>> compiling for a target that does not support a device tree.
>> At least that is my understanding of this condition.
> 
> There should be stubs for all these functions, so if OF is not part of
> the configured kernel, stub functions take their place. That has the
> advantage of at least compiling the code, so checking parameter types
> etc. We try to avoid #ifdef where possible, so we get better compiler
> build test coverage. The more #ifef there are, the more different
> configurations that need compiling in order to get build coverage.
> 
> 	       Andrew
> 

The phy_get_internal_delay() function does not have a stub function 
directly, but it calls phy_get_int_delay_property() which has a stub, if 
CONFIG_OF_MDIO is not set, see:
https://elixir.bootlin.com/linux/v5.14-rc1/source/drivers/net/phy/phy_device.c#L2797

The extra ifdef in the PHY driver only saves some code in the HY driver, 
but it should still work as before on systems without CONFIG_OF_MDIO.

I would also prefer to remove the ifdef from the intel-xway phy driver.

Hauke

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH net-next v3] net: phy: intel-xway: Add RGMII internal delay configuration
  2021-07-17 16:38       ` Hauke Mehrtens
@ 2021-07-19  8:14         ` Martin Schiller
  0 siblings, 0 replies; 6+ messages in thread
From: Martin Schiller @ 2021-07-19  8:14 UTC (permalink / raw)
  To: Hauke Mehrtens
  Cc: Andrew Lunn, Martin Blumenstingl, f.fainelli, hkallweit1, linux,
	davem, kuba, netdev, linux-kernel

On 2021-07-17 18:38, Hauke Mehrtens wrote:
> On 7/13/21 3:06 PM, Andrew Lunn wrote:
>>>> [...]
>>>>> +#if IS_ENABLED(CONFIG_OF_MDIO)
>>>> is there any particular reason why we need to guard this with
>>>> CONFIG_OF_MDIO?
>>>> The dp83822 driver does not use this #if either (as far as I
>>>> understand at least)
>>>> 
>>> 
>>> It makes no sense to retrieve properties from the device tree if we 
>>> are
>>> compiling for a target that does not support a device tree.
>>> At least that is my understanding of this condition.
>> 
>> There should be stubs for all these functions, so if OF is not part of
>> the configured kernel, stub functions take their place. That has the
>> advantage of at least compiling the code, so checking parameter types
>> etc. We try to avoid #ifdef where possible, so we get better compiler
>> build test coverage. The more #ifef there are, the more different
>> configurations that need compiling in order to get build coverage.
>> 
>> 	       Andrew
>> 
> 
> The phy_get_internal_delay() function does not have a stub function
> directly, but it calls phy_get_int_delay_property() which has a stub,
> if CONFIG_OF_MDIO is not set, see:
> https://elixir.bootlin.com/linux/v5.14-rc1/source/drivers/net/phy/phy_device.c#L2797
> 
> The extra ifdef in the PHY driver only saves some code in the HY
> driver, but it should still work as before on systems without
> CONFIG_OF_MDIO.
> 
> I would also prefer to remove the ifdef from the intel-xway phy driver.
> 
> Hauke

OK, so I'll remove the ifdef from the driver.


^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2021-07-19  9:07 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2021-07-09 16:42 [PATCH net-next v3] net: phy: intel-xway: Add RGMII internal delay configuration Martin Schiller
2021-07-09 18:31 ` Martin Blumenstingl
2021-07-12  6:13   ` Martin Schiller
2021-07-13 13:06     ` Andrew Lunn
2021-07-17 16:38       ` Hauke Mehrtens
2021-07-19  8:14         ` Martin Schiller

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