[PATCH linux dev-4.13 1/6] gpio/aspeed: Set output latch before changing direction

[Christopher Bostic]

Reviewed-by: Christopher Bostic <cbostic at linux.vnet.ibm.com>


On 5/7/18 8:06 PM, Benjamin Herrenschmidt wrote:
> In aspeed_gpio_dir_out(), we need to establish the new output
> value in the output latch *before* we change the direction
> to output in order to avoid a glitch on the output line if
> the previous value of the latch was different.
>
> Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
> ---
>   drivers/gpio/gpio-aspeed.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/gpio/gpio-aspeed.c b/drivers/gpio/gpio-aspeed.c
> index 67f3eae3b550..ac54b9b25f74 100644
> --- a/drivers/gpio/gpio-aspeed.c
> +++ b/drivers/gpio/gpio-aspeed.c
> @@ -287,11 +287,10 @@ static int aspeed_gpio_dir_out(struct gpio_chip *gc,
>
>   	spin_lock_irqsave(&gpio->lock, flags);
>
> +	__aspeed_gpio_set(gc, offset, val);
>   	reg = ioread32(bank_val_reg(gpio, bank, GPIO_DIR));
>   	iowrite32(reg | GPIO_BIT(offset), bank_val_reg(gpio, bank, GPIO_DIR));
>
> -	__aspeed_gpio_set(gc, offset, val);
> -
>   	spin_unlock_irqrestore(&gpio->lock, flags);
>
>   	return 0;