Re: [PATCH v2] pinctrl: samsung: Fixes samsung_gpio_direction_in/output releated with spinlock

[Youngmin Nam <ym0914@gmail.com>]

Thanks Linus and Tomasz.

Sorry for late. I will rebase on v4.5-rc3 and resend.

Thanks.

On 2016년 01월 27일 21:36, Linus Walleij wrote:
> On Sun, Jan 24, 2016 at 7:02 AM, Youngmin Nam <ym0914@gmail.com> wrote:
> 
>> Previously, samsung_gpio_drection_in/output function were not covered with
>> one spinlock.
>>
>> For example, samsung_gpio_direction_output function consists of two functions.
>> 1. samsung_gpio_set
>> 2. samsung_gpio_set_direction
>>
>> When 2 CPUs try to control the same gpio pin heavily,
>> (situation like i2c control with gpio emulation)
>> This situation can cause below problem.
>>
>> CPU 0                                   | CPU1
>>                                         |
>> samsung_gpio_direction_output           |
>>    samsung_gpio_set(pin A as 1)         | samsung_gpio_direction_output
>>                                         |    samsung_gpio_set(pin A as 0)
>>    samsung_gpio_set_direction           |
>>                                         |    samsung_gpio_set_direction
>>
>> The initial value of pin A will be set as 0 while we wanted to set pin A as 1.
>>
>> This patch modifies samsung_gpio_direction_in/output function
>> to be done in one spinlock to fix race condition.
>>
>> Additionally, the new samsung_gpio_set_value was added to implement
>> gpio set callback(samsung_gpio_set) with spinlock using this function.
>>
>> Signed-off-by: Youngmin Nam <ym0914@gmail.com>
> 
> This patch does not apply to v4.5-rc1. Please rebase this
> and resend. (With Thomas ACK if it's valid.)
> 
> Yours,
> Linus Walleij
>