Re: [PATCH V2 3/3] gpio: tegra: Add support for gpio debounce

From: Stephen Warren
Date: Tue Apr 19 2016 - 12:12:11 EST

On 04/19/2016 03:43 AM, Laxman Dewangan wrote:
NVIDIA's Tegra210 support the HW debounce in the GPIO
controller for all its GPIO pins.

Add support for setting debounce timing by implementing the
set_debounce callback of gpiochip.

diff --git a/drivers/gpio/gpio-tegra.c b/drivers/gpio/gpio-tegra.c

@@ -327,6 +360,9 @@ static int tegra_gpio_resume(struct device *dev)
tegra_gpio_writel(bank->oe[p], GPIO_OE(gpio));
tegra_gpio_writel(bank->int_lvl[p], GPIO_INT_LVL(gpio));
tegra_gpio_writel(bank->int_enb[p], GPIO_INT_ENB(gpio));
+ tegra_gpio_writel(bank->dbc_cnt[p], GPIO_DBC_CNT(gpio));
+ tegra_gpio_writel(bank->dbc_enb[p],
+ GPIO_MSK_DBC_EN(gpio));

Why not just write to the "regular" register rather than the mask register here...

@@ -351,6 +387,10 @@ static int tegra_gpio_suspend(struct device *dev)
bank->oe[p] = tegra_gpio_readl(GPIO_OE(gpio));
bank->int_enb[p] = tegra_gpio_readl(GPIO_INT_ENB(gpio));
bank->int_lvl[p] = tegra_gpio_readl(GPIO_INT_LVL(gpio));
+ bank->dbc_enb[p] = tegra_gpio_readl(
+ GPIO_MSK_DBC_EN(gpio));
+ bank->dbc_enb[p] = (bank->dbc_enb[p] << 8) ||
+ bank->dbc_enb[p];

... since that would avoid having to or in the mask value in the saved register value here; you could just save/restore the regular register in the same way as any other register.