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From: Stephen Boyd <sboyd@codeaurora.org>
To: "Ivan T. Ivanov" <iivanov@mm-sol.com>
Cc: Mark Brown <broonie@kernel.org>,
	linus.walleij@linaro.org, linux-spi@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org
Subject: Re: [PATCH 2/2] spi: qup: Request CS GPIO's during probe
Date: Mon, 09 Mar 2015 11:53:42 -0700	[thread overview]
Message-ID: <54FDEC36.5080403@codeaurora.org> (raw)
In-Reply-To: <1425889207.2440.9.camel@mm-sol.com>

On 03/09/15 01:20, Ivan T. Ivanov wrote:
> Hi Stephen,
>
>> On Mar 6, 2015, at 8:34 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
>> On 03/06/15 07:26, Ivan T. Ivanov wrote:
>>> Ensure that driver is owner of the GPIO's used for CS signals.
>> Why? What happens if we don’t?
> We can have wrong DT configuration, which could reconfigure
> GPIO’s without any warning or error.

Ouch. That sounds bad. Can you please add this information to the commit
text?

>
>>> Signed-off-by: Ivan T. Ivanov <iivanov@mm-sol.com>
>>> ---
>>> drivers/spi/spi-qup.c | 17 ++++++++++++++++-
>>> 1 file changed, 16 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/spi/spi-qup.c b/drivers/spi/spi-qup.c
>>> index 2b2c359..a07ba46 100644
>>> --- a/drivers/spi/spi-qup.c
>>> +++ b/drivers/spi/spi-qup.c
>>> @@ -14,11 +14,13 @@
>>> #include <linux/clk.h>
>>> #include <linux/delay.h>
>>> #include <linux/err.h>
>>> +#include <linux/gpio.h>
>>> #include <linux/interrupt.h>
>>> #include <linux/io.h>
>>> #include <linux/list.h>
>>> #include <linux/module.h>
>>> #include <linux/of.h>
>>> +#include <linux/of_gpio.h>
>>> #include <linux/platform_device.h>
>>> #include <linux/pm_runtime.h>
>>> #include <linux/spi/spi.h>
>>> @@ -499,7 +501,7 @@ static int spi_qup_probe(struct platform_device *pdev)
>>>         struct device *dev;
>>>         void __iomem *base;
>>>         u32 max_freq, iomode, num_cs;
>>> -       int ret, irq, size;
>>> +       int ret, irq, size, cs, cs_gpio;
>>>
>>>         dev = &pdev->dev;
>>>         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>> @@ -556,6 +558,19 @@ static int spi_qup_probe(struct platform_device *pdev)
>>>         else
>>>                 master->num_chipselect = num_cs;
>>>
>>> +       for (cs = 0; cs < master->num_chipselect; cs++) {
>>> +               cs_gpio = of_get_named_gpio(dev->of_node, "cs-gpios", cs);
>>> +
>>> +               if (!gpio_is_valid(cs_gpio))
>>> +                       continue;
>>> +
>>> +               ret = devm_gpio_request(&pdev->dev, cs_gpio, "spi-qup-cs");
>>> +               if (ret) {
>>> +                       dev_err(&pdev->dev, "can't get cs gpios\n");
>>> +                       goto error;
>>> +               }
>>> +       }
>>> +
>>>         master->bus_num = pdev->id;
>> Is this related to [1]? In that case I was just relying on DT/pinctrl to
>> properly request the gpios.
> But the DT/pinctrl did not request GPIO’s, it just configure them.
> For some reason we are ending without any pinctrl_map of type 
> PIN_MAP_TYPE_MUX_GROUP, which is used for pin reservation. 
>

Ah ok. I seem to be misremembering the details.

Can you please use the gpiod interfaces here (devm_gpiod_get_index)?
That's more modern. Also, don't print any error because -EPROBE_DEFER
may come out and because __gpiod_get_index() already prints an error on
failure at the debug level.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project


  reply	other threads:[~2015-03-09 18:53 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-06 15:26 [PATCH 1/2] spi: qup: Fix cs-num DT property parsing Ivan T. Ivanov
2015-03-06 15:26 ` [PATCH 2/2] spi: qup: Request CS GPIO's during probe Ivan T. Ivanov
2015-03-06 18:34   ` Stephen Boyd
2015-03-09  8:20     ` Ivan T. Ivanov
2015-03-09 18:53       ` Stephen Boyd [this message]
2015-03-10  8:31         ` Ivan T. Ivanov
2015-03-17 11:02         ` Ivan T. Ivanov
2015-03-07 10:59   ` Mark Brown
     [not found]     ` <1425889415.2440.10.camel@mm-sol.com>
     [not found]       ` <20150309182841.GW28806@sirena.org.uk>
2015-03-10  8:10         ` Ivan T. Ivanov
2015-03-10 11:06           ` Mark Brown
2015-03-10 12:53             ` Ivan T. Ivanov
2015-03-10 20:47               ` Mark Brown
2015-03-07 11:01 ` [PATCH 1/2] spi: qup: Fix cs-num DT property parsing Mark Brown

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