[PATCH] spi: atmel: use managed resource for gpio chip select

[PATCH] spi: atmel: use managed resource for gpio chip select

[Nicolas Ferre]

Use the managed gpio CS pin request so that we avoid having trouble
in the cleanup code.
In fact, if module was configured with DT, cleanup code released
invalid pin.  Since resource wasn't freed, module cannot be reinserted.

Reported-by: Alexander Morozov <linux@meltdown.ru>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
---
 drivers/spi/spi-atmel.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
index 8feac599e9ab..4e3f2345844a 100644
--- a/drivers/spi/spi-atmel.c
+++ b/drivers/spi/spi-atmel.c
@@ -1248,7 +1248,8 @@ static int atmel_spi_setup(struct spi_device *spi)
 			return -ENOMEM;
 
 		if (as->use_cs_gpios) {
-			ret = gpio_request(npcs_pin, dev_name(&spi->dev));
+			ret = devm_gpio_request(&spi->dev,
+						npcs_pin, dev_name(&spi->dev));
 			if (ret) {
 				kfree(asd);
 				return ret;
@@ -1471,13 +1472,11 @@ static int atmel_spi_transfer_one_message(struct spi_master *master,
 static void atmel_spi_cleanup(struct spi_device *spi)
 {
 	struct atmel_spi_device	*asd = spi->controller_state;
-	unsigned		gpio = (unsigned long) spi->controller_data;
 
 	if (!asd)
 		return;
 
 	spi->controller_state = NULL;
-	gpio_free(gpio);
 	kfree(asd);
 }
 
-- 
2.9.0

Re: [PATCH] spi: atmel: use managed resource for gpio chip select

[Geert Uytterhoeven]

Hi Nicolas,

On Wed, Sep 21, 2016 at 9:55 AM, Nicolas Ferre <nicolas.ferre@atmel.com> wrote:
> Use the managed gpio CS pin request so that we avoid having trouble
> in the cleanup code.
> In fact, if module was configured with DT, cleanup code released
> invalid pin.  Since resource wasn't freed, module cannot be reinserted.
>
> Reported-by: Alexander Morozov <linux@meltdown.ru>
> Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
> ---
>  drivers/spi/spi-atmel.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
> index 8feac599e9ab..4e3f2345844a 100644
> --- a/drivers/spi/spi-atmel.c
> +++ b/drivers/spi/spi-atmel.c
> @@ -1248,7 +1248,8 @@ static int atmel_spi_setup(struct spi_device *spi)
>                         return -ENOMEM;
>
>                 if (as->use_cs_gpios) {
> -                       ret = gpio_request(npcs_pin, dev_name(&spi->dev));
> +                       ret = devm_gpio_request(&spi->dev,
> +                                               npcs_pin, dev_name(&spi->dev));

Note that spi_master.setup() can be called multiple times during the lifetime
of the spi_device.

>                         if (ret) {
>                                 kfree(asd);
>                                 return ret;
> @@ -1471,13 +1472,11 @@ static int atmel_spi_transfer_one_message(struct spi_master *master,
>  static void atmel_spi_cleanup(struct spi_device *spi)
>  {
>         struct atmel_spi_device *asd = spi->controller_state;
> -       unsigned                gpio = (unsigned long) spi->controller_data;
>
>         if (!asd)
>                 return;
>
>         spi->controller_state = NULL;
> -       gpio_free(gpio);
>         kfree(asd);
>  }

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] spi: atmel: use managed resource for gpio chip select

[Nicolas Ferre]

Le 21/09/2016 à 10:20, Geert Uytterhoeven a écrit :
> Hi Nicolas,
> 
> On Wed, Sep 21, 2016 at 9:55 AM, Nicolas Ferre <nicolas.ferre@atmel.com> wrote:
>> Use the managed gpio CS pin request so that we avoid having trouble
>> in the cleanup code.
>> In fact, if module was configured with DT, cleanup code released
>> invalid pin.  Since resource wasn't freed, module cannot be reinserted.
>>
>> Reported-by: Alexander Morozov <linux@meltdown.ru>
>> Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
>> ---
>>  drivers/spi/spi-atmel.c | 5 ++---
>>  1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
>> index 8feac599e9ab..4e3f2345844a 100644
>> --- a/drivers/spi/spi-atmel.c
>> +++ b/drivers/spi/spi-atmel.c
>> @@ -1248,7 +1248,8 @@ static int atmel_spi_setup(struct spi_device *spi)
>>                         return -ENOMEM;
>>
>>                 if (as->use_cs_gpios) {
>> -                       ret = gpio_request(npcs_pin, dev_name(&spi->dev));
>> +                       ret = devm_gpio_request(&spi->dev,
>> +                                               npcs_pin, dev_name(&spi->dev));
> 
> Note that spi_master.setup() can be called multiple times during the lifetime
> of the spi_device.

Sure, this is what I read in include/linux/spi/spi.h "It's always safe
to call this unless transfers are pending on the device whose settings
are being modified."

It also means that the whole memory allocation for devices that is done
a few lines above this gpio request is also completely wrong... This
function needs a serious refactoring.

Thanks for the heads-up.

Best regards,

>>                         if (ret) {
>>                                 kfree(asd);
>>                                 return ret;
>> @@ -1471,13 +1472,11 @@ static int atmel_spi_transfer_one_message(struct spi_master *master,
>>  static void atmel_spi_cleanup(struct spi_device *spi)
>>  {
>>         struct atmel_spi_device *asd = spi->controller_state;
>> -       unsigned                gpio = (unsigned long) spi->controller_data;
>>
>>         if (!asd)
>>                 return;
>>
>>         spi->controller_state = NULL;
>> -       gpio_free(gpio);
>>         kfree(asd);
>>  }
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds
> 


-- 
Nicolas Ferre