On 17.01.2016 16:41, Youngmin Nam 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, gpio set callback was changed with samsung_gpio_set_value
> to implement gpio set callback with spinlock using samsung_gpio_set.
>
> Signed-off-by: Youngmin Nam <ym0914@xxxxxxxxx>
> ---
> drivers/pinctrl/samsung/pinctrl-samsung.c | 38 ++++++++++++++++++++++---------
> 1 file changed, 27 insertions(+), 11 deletions(-)
Hi,
Thank you for the patch.
Unfortunately you sent it to insufficient number of folks. Actually you
skipped all of necessary people.
Please use the scripts/get_maintainer.pl script to obtain a list of
maintainers which you should put on CC (Tomasz, Linus and more mailing
lists, including the gpio list).
Can you resend the patch CC-ing all necessary guys and lists?
Best regards,
Krzysztof
>
> diff --git a/drivers/pinctrl/samsung/pinctrl-samsung.c b/drivers/pinctrl/samsung/pinctrl-samsung.c
> index 48294e7..a25f6f6 100644
> --- a/drivers/pinctrl/samsung/pinctrl-samsung.c
> +++ b/drivers/pinctrl/samsung/pinctrl-samsung.c
> @@ -524,20 +524,26 @@ static void samsung_gpio_set(struct gpio_chip *gc, unsigned offset, int value)
> {
> struct samsung_pin_bank *bank = gc_to_pin_bank(gc);
> const struct samsung_pin_bank_type *type = bank->type;
> - unsigned long flags;
> void __iomem *reg;
> u32 data;
>
> reg = bank->drvdata->virt_base + bank->pctl_offset;
>
> - spin_lock_irqsave(&bank->slock, flags);
> -
> data = readl(reg + type->reg_offset[PINCFG_TYPE_DAT]);
> data &= ~(1 << offset);
> if (value)
> data |= 1 << offset;
> writel(data, reg + type->reg_offset[PINCFG_TYPE_DAT]);
> +}
> +
> +static void samsung_gpio_set_value(struct gpio_chip *gc,
> + unsigned offset, int value)
> +{
> + struct samsung_pin_bank *bank = gc_to_pin_bank(gc);
> + unsigned long flags;
>
> + spin_lock_irqsave(&bank->slock, flags);
> + samsung_gpio_set(gc, offset, value);
> spin_unlock_irqrestore(&bank->slock, flags);
> }
>
> @@ -569,7 +575,6 @@ static int samsung_gpio_set_direction(struct gpio_chip *gc,
> struct samsung_pinctrl_drv_data *drvdata;
> void __iomem *reg;
> u32 data, mask, shift;
> - unsigned long flags;
>
> bank = gc_to_pin_bank(gc);
> type = bank->type;
> @@ -586,31 +591,42 @@ static int samsung_gpio_set_direction(struct gpio_chip *gc,
> reg += 4;
> }
>
> - spin_lock_irqsave(&bank->slock, flags);
> -
> data = readl(reg);
> data &= ~(mask << shift);
> if (!input)
> data |= FUNC_OUTPUT << shift;
> writel(data, reg);
>
> - spin_unlock_irqrestore(&bank->slock, flags);
> -
> return 0;
> }
>
> /* gpiolib gpio_direction_input callback function. */
> static int samsung_gpio_direction_input(struct gpio_chip *gc, unsigned offset)
> {
> - return samsung_gpio_set_direction(gc, offset, true);
> + struct samsung_pin_bank *bank = gc_to_pin_bank(gc);
> + unsigned long flags;
> + int ret;
> +
> + spin_lock_irqsave(&bank->slock, flags);
> + ret = samsung_gpio_set_direction(gc, offset, true);
> + spin_unlock_irqrestore(&bank->slock, flags);
> + return ret;
> }
>
> /* gpiolib gpio_direction_output callback function. */
> static int samsung_gpio_direction_output(struct gpio_chip *gc, unsigned offset,
> int value)
> {
> + struct samsung_pin_bank *bank = gc_to_pin_bank(gc);
> + unsigned long flags;
> + int ret;
> +
> + spin_lock_irqsave(&bank->slock, flags);
> samsung_gpio_set(gc, offset, value);
> - return samsung_gpio_set_direction(gc, offset, false);
> + ret = samsung_gpio_set_direction(gc, offset, false);
> + spin_unlock_irqrestore(&bank->slock, flags);
> +
> + return ret;
> }
>
> /*
> @@ -891,7 +907,7 @@ static int samsung_pinctrl_register(struct platform_device *pdev,
> static const struct gpio_chip samsung_gpiolib_chip = {
> .request = gpiochip_generic_request,
> .free = gpiochip_generic_free,
> - .set = samsung_gpio_set,
> + .set = samsung_gpio_set_value,
> .get = samsung_gpio_get,
> .direction_input = samsung_gpio_direction_input,
> .direction_output = samsung_gpio_direction_output,
>
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