From mboxrd@z Thu Jan 1 00:00:00 1970 From: Javier Martinez Canillas Subject: Re: Re: [PATCH] gpio/at91: free GPIO after configuring as input Date: Fri, 11 Apr 2014 19:28:08 +0200 Message-ID: References: <1397226249-3922-1-git-send-email-alexanders83@web.de> <4406073.7Z2odFudGD@kongar> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: Received: from mail-we0-f170.google.com ([74.125.82.170]:50954 "EHLO mail-we0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755985AbaDKR2K (ORCPT ); Fri, 11 Apr 2014 13:28:10 -0400 Received: by mail-we0-f170.google.com with SMTP id w61so5757998wes.1 for ; Fri, 11 Apr 2014 10:28:08 -0700 (PDT) In-Reply-To: <4406073.7Z2odFudGD@kongar> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Alexander Stein Cc: Jean-Christophe PLAGNIOL-VILLARD , Dmitry Torokhov , Linus Walleij , "linux-arm-kernel@lists.infradead.org" , linux-input@vger.kernel.org On Fri, Apr 11, 2014 at 5:45 PM, Alexander Stein wrote: > I'm CC'ing some input guys if this can't be solved in the pinctrl/irq side. > > On Friday 11 April 2014, 23:30:33 wrote Jean-Christophe PLAGNIOL-VILLARD: >> >> On Apr 11, 2014, at 10:24 PM, Alexander Stein wrote: >> >> > >> > If the GPIO stays requested a device driver can't request it again. >> > e.g. Without this patch the ads7846 driver returns the following error: >> > ads7846 spi32766.3: failed to request/setup pendown GPIO15: -16 >> > ads7846: probe of spi32766.3 failed with error -16 >> > >> > /sys/kernel/debug/gpio shows this: >> > GPIOs 0-31, platform/fffff200.gpio, fffff200.gpio: >> > [/ahb/apb/pinctrl@fffff200/gpio@fffff200] GPIOfffff200.gpio15: [gpio] set >> > >> > Signed-off-by: Alexander Stein >> > --- >> > I'm aware that it makes sense this GPIO is/stays requested, but either the >> > pinctl or device driver have to be adjusted as both can't request this GPIO. >> > I think the latter shouldn't change. >> > >> > drivers/pinctrl/pinctrl-at91.c | 2 ++ >> > 1 file changed, 2 insertions(+) >> > >> > diff --git a/drivers/pinctrl/pinctrl-at91.c b/drivers/pinctrl/pinctrl-at91.c >> > index d990e33..63176f2 100644 >> > --- a/drivers/pinctrl/pinctrl-at91.c >> > +++ b/drivers/pinctrl/pinctrl-at91.c >> > @@ -1493,6 +1493,8 @@ static int at91_gpio_irq_domain_xlate(struct irq_domain *d, >> > if (ret) >> > return ret; >> > >> > + gpio_free(pin); >> > + >> >> NACK it the whole key point the gpio use as a IRQ so the irq generic code request it >> > return 0; >> > } >> > >> The problem is that the GPIO and IRQ subsystems are somehow related but completely independent. A GPIO pin used as an IRQ line is completely orthogonal to requesting a GPIO pin. Is true that here is a common pattern in the kernel that is: gpio_request(gpio,...); gpio_direction_input() request[_threaded]_irq(gpio_to_irq(gpio), ...); But one should not assume that requesting a GPIO to be used as an IRQ line implies requesting the GPIO first. It is completely legal to only request the IRQ without requesting the GPIO before. Of course at a hardware level the pin has to be configured as input if needed by the chip controller and also a following call to gpio_request() as output should not be supported. After a long discussion the agreement is that the driver should be able to setup as a hw level if another driver wants to use a GPIO pin as an IRQ line but not requesting the GPIO. So, I think that is wrong to call gpio_request() and gpio_direction_input() on a irq_domain_ops .xlate() function handler since by doing that a subsequent call to gpio_request() is failing like you are reporting. The GPIO subsystem has a new gpio_lock_as_irq() helper function to mark a GPIO pin as already used as a IRQ line and only allowing to request a GPIO as input if is already marked as an IRQ. Please take a look to commit 2f56e0a ("gpio/omap: use gpiolib API to mark a GPIO used as an IRQ") for an example on how to use this helper function. Also, there is a new GPIOLIB_IRQCHIP infrastructure in gpiolib that are a set of helper functions to associate an IRQ chip to a GPIO controller. This should cover the most common use case and most probably this driver and can be converted to use it. Please refer to commits: 1425052 ("gpio: add IRQ chip helpers in gpiolib") e0bc34a ("pinctrl: nomadik: convert driver to use gpiolib irqchip") for an example on how to use it. Thanks a lot and best regards, Javier From mboxrd@z Thu Jan 1 00:00:00 1970 From: javier@dowhile0.org (Javier Martinez Canillas) Date: Fri, 11 Apr 2014 19:28:08 +0200 Subject: [PATCH] gpio/at91: free GPIO after configuring as input In-Reply-To: <4406073.7Z2odFudGD@kongar> References: <1397226249-3922-1-git-send-email-alexanders83@web.de> <4406073.7Z2odFudGD@kongar> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, Apr 11, 2014 at 5:45 PM, Alexander Stein wrote: > I'm CC'ing some input guys if this can't be solved in the pinctrl/irq side. > > On Friday 11 April 2014, 23:30:33 wrote Jean-Christophe PLAGNIOL-VILLARD: >> >> On Apr 11, 2014, at 10:24 PM, Alexander Stein wrote: >> >> > >> > If the GPIO stays requested a device driver can't request it again. >> > e.g. Without this patch the ads7846 driver returns the following error: >> > ads7846 spi32766.3: failed to request/setup pendown GPIO15: -16 >> > ads7846: probe of spi32766.3 failed with error -16 >> > >> > /sys/kernel/debug/gpio shows this: >> > GPIOs 0-31, platform/fffff200.gpio, fffff200.gpio: >> > [/ahb/apb/pinctrl at fffff200/gpio at fffff200] GPIOfffff200.gpio15: [gpio] set >> > >> > Signed-off-by: Alexander Stein >> > --- >> > I'm aware that it makes sense this GPIO is/stays requested, but either the >> > pinctl or device driver have to be adjusted as both can't request this GPIO. >> > I think the latter shouldn't change. >> > >> > drivers/pinctrl/pinctrl-at91.c | 2 ++ >> > 1 file changed, 2 insertions(+) >> > >> > diff --git a/drivers/pinctrl/pinctrl-at91.c b/drivers/pinctrl/pinctrl-at91.c >> > index d990e33..63176f2 100644 >> > --- a/drivers/pinctrl/pinctrl-at91.c >> > +++ b/drivers/pinctrl/pinctrl-at91.c >> > @@ -1493,6 +1493,8 @@ static int at91_gpio_irq_domain_xlate(struct irq_domain *d, >> > if (ret) >> > return ret; >> > >> > + gpio_free(pin); >> > + >> >> NACK it the whole key point the gpio use as a IRQ so the irq generic code request it >> > return 0; >> > } >> > >> The problem is that the GPIO and IRQ subsystems are somehow related but completely independent. A GPIO pin used as an IRQ line is completely orthogonal to requesting a GPIO pin. Is true that here is a common pattern in the kernel that is: gpio_request(gpio,...); gpio_direction_input() request[_threaded]_irq(gpio_to_irq(gpio), ...); But one should not assume that requesting a GPIO to be used as an IRQ line implies requesting the GPIO first. It is completely legal to only request the IRQ without requesting the GPIO before. Of course at a hardware level the pin has to be configured as input if needed by the chip controller and also a following call to gpio_request() as output should not be supported. After a long discussion the agreement is that the driver should be able to setup as a hw level if another driver wants to use a GPIO pin as an IRQ line but not requesting the GPIO. So, I think that is wrong to call gpio_request() and gpio_direction_input() on a irq_domain_ops .xlate() function handler since by doing that a subsequent call to gpio_request() is failing like you are reporting. The GPIO subsystem has a new gpio_lock_as_irq() helper function to mark a GPIO pin as already used as a IRQ line and only allowing to request a GPIO as input if is already marked as an IRQ. Please take a look to commit 2f56e0a ("gpio/omap: use gpiolib API to mark a GPIO used as an IRQ") for an example on how to use this helper function. Also, there is a new GPIOLIB_IRQCHIP infrastructure in gpiolib that are a set of helper functions to associate an IRQ chip to a GPIO controller. This should cover the most common use case and most probably this driver and can be converted to use it. Please refer to commits: 1425052 ("gpio: add IRQ chip helpers in gpiolib") e0bc34a ("pinctrl: nomadik: convert driver to use gpiolib irqchip") for an example on how to use it. Thanks a lot and best regards, Javier