linux-kernel - Re: [PATCH v3 -next] Input: gpio_keys: set input direction explicitly for gpio keys

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Date:   Thu, 17 Nov 2016 09:48:24 +0000
From:   Sudeep Holla <sudeep.holla@....com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     Sudeep Holla <sudeep.holla@....com>, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: Re: [PATCH v3 -next] Input: gpio_keys: set input direction explicitly
 for gpio keys



On 17/11/16 01:18, Dmitry Torokhov wrote:
> On Wed, Nov 16, 2016 at 06:38:22PM +0000, Sudeep Holla wrote:
>> Commit 700a38b27eef ("Input: gpio_keys - switch to using generic device
>> properties") switched to use generic device properties for GPIO keys and
>> commit 5feeca3c1e39 ("Input: gpio_keys - add support for GPIO descriptors")
>> switched from legacy GPIO numbers to GPIO descriptors.
>>
>> Previously devm_gpio_request_one was explicitly passed GPIOF_DIR_IN flag
>> to set the GPIO direction as input. However devm_get_gpiod_from_child
>> doesn't have such provisions and hence fwnode_get_named_gpiod can't set
>> it as input.
>>
>> This breaks few platforms with the following error:
>> " gpiochip_lock_as_irq: tried to flag a GPIO set as output for IRQ
>>   unable to lock HW IRQ <n> for IRQ
>>   genirq: Failed to request resources for POWER (irq <x>) on irqchip
>>   gpio_keys: Unable to claim irq <x>; error -22
>>   gpio-keys: probe failed with error -22 "
>>
>> This patch fixes the issue by setting input direction explicitly for
>> gpio input keys. It also remove the existing GPIOF_DIR_IN flag setting
>> for the legacy gpios and merges into single gpiod_direction_input call.
>>
>> Fixes: 700a38b27eef ("Input: gpio_keys - switch to using generic device properties")
>> Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>
>> Cc: Linus Walleij <linus.walleij@...aro.org>
>> Cc: Geert Uytterhoeven <geert+renesas@...der.be>
>> Cc: Mika Westerberg <mika.westerberg@...ux.intel.com>
>> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
>> ---
>>  drivers/input/keyboard/gpio_keys.c        | 10 +++++++++-
>>  drivers/input/keyboard/gpio_keys_polled.c | 10 +++++++++-
>>  2 files changed, 18 insertions(+), 2 deletions(-)
>>
>> v2->v3:
>> 	- Added error handling and error message
>>
>> diff --git a/drivers/input/keyboard/gpio_keys.c b/drivers/input/keyboard/gpio_keys.c
>> index 5576f2ae0b71..ed38a05b3039 100644
>> --- a/drivers/input/keyboard/gpio_keys.c
>> +++ b/drivers/input/keyboard/gpio_keys.c
>> @@ -502,7 +502,7 @@ static int gpio_keys_setup_key(struct platform_device *pdev,
>>  		 * Legacy GPIO number, so request the GPIO here and
>>  		 * convert it to descriptor.
>>  		 */
>> -		unsigned flags = GPIOF_IN;
>> +		unsigned flags = 0;
>>
>>  		if (button->active_low)
>>  			flags |= GPIOF_ACTIVE_LOW;
>
> Sudeep, I looked into this aa bit deeper, and I have issue with this
> part: in absence of GPIOF_IN devm_gpio_request_one() will attempt to
> configure GPIO line as output, which may not work. Because of this I
> think we should move gpiod_direction_input() call into the "modern"
> branch and leave legacy branch as is.
>
> Does the version below work for you?
>

Yes it does and in fact I started with something similar and then saw
that I can make it common between legacy and new branch conditions. So I
am fine with the modified version you sent.

-- 
Regards,
Sudeep