Re: [PATCH v3] PCI: imx6: Fix reset-gpio to work with active low GPIO

[Bjorn Helgaas <helgaas@kernel.org>]

[+cc Jingoo]

On Fri, Dec 04, 2015 at 02:59:06PM -0600, Bjorn Helgaas wrote:
> On Fri, Nov 27, 2015 at 11:56:34AM +0100, Petr Štetiar wrote:
> > It's currently not possible to use reset-gpio on board where the GPIO is
> > active low as the code incorrectly assumes, that reset-gpio will be
> > always active high.
> > 
> > In my case the broken behavior was observed on Toradex Apalis SoM with
> > Ixora base board.
> > 
> > Signed-off-by: Petr Štetiar <ynezz@true.cz>
> 
> Applied as follows with Lucas' reviewed-by to pci/host-imx6 for v4.5,
> thanks!

Jingoo, I noticed pci-exynos.c also uses of_get_named_gpio().  Do you
care about this issue, too, or are you content to ignore the GPIO
flags for your "reset-gpio"?

Bjorn

> commit 5c5fb40de8f14391a1238db05cef88754faf9229
> Author: Petr Štetiar <ynezz@true.cz>
> Date:   Fri Nov 27 11:56:34 2015 +0100
> 
>     PCI: imx6: Add support for active-low reset GPIO
>     
>     We previously used of_get_named_gpio(), which ignores the OF flags cell, so
>     the reset GPIO defaulted to "active high." This doesn't work on the Toradex
>     Apalis SoM with Ixora base board, which has an active-low reset GPIO.
>     
>     Use devm_gpiod_get_optional() instead so we pay attention to the active
>     high/low flag.  This also adds support for GPIOs described via ACPI.
>     
>     [bhelgaas: changelog]
>     Signed-off-by: Petr Štetiar <ynezz@true.cz>
>     Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
>     Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
> 
> diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
> index 3c3b37f..8e9afa5 100644
> --- a/drivers/pci/host/pci-imx6.c
> +++ b/drivers/pci/host/pci-imx6.c
> @@ -32,7 +32,7 @@
>  #define to_imx6_pcie(x)	container_of(x, struct imx6_pcie, pp)
>  
>  struct imx6_pcie {
> -	int			reset_gpio;
> +	struct gpio_desc	*reset_gpio;
>  	struct clk		*pcie_bus;
>  	struct clk		*pcie_phy;
>  	struct clk		*pcie;
> @@ -287,10 +287,10 @@ static int imx6_pcie_deassert_core_reset(struct pcie_port *pp)
>  	usleep_range(200, 500);
>  
>  	/* Some boards don't have PCIe reset GPIO. */
> -	if (gpio_is_valid(imx6_pcie->reset_gpio)) {
> -		gpio_set_value_cansleep(imx6_pcie->reset_gpio, 0);
> +	if (imx6_pcie->reset_gpio) {
> +		gpiod_set_value_cansleep(imx6_pcie->reset_gpio, 0);
>  		msleep(100);
> -		gpio_set_value_cansleep(imx6_pcie->reset_gpio, 1);
> +		gpiod_set_value_cansleep(imx6_pcie->reset_gpio, 1);
>  	}
>  	return 0;
>  
> @@ -560,7 +560,6 @@ static int __init imx6_pcie_probe(struct platform_device *pdev)
>  {
>  	struct imx6_pcie *imx6_pcie;
>  	struct pcie_port *pp;
> -	struct device_node *np = pdev->dev.of_node;
>  	struct resource *dbi_base;
>  	int ret;
>  
> @@ -581,15 +580,8 @@ static int __init imx6_pcie_probe(struct platform_device *pdev)
>  		return PTR_ERR(pp->dbi_base);
>  
>  	/* Fetch GPIOs */
> -	imx6_pcie->reset_gpio = of_get_named_gpio(np, "reset-gpio", 0);
> -	if (gpio_is_valid(imx6_pcie->reset_gpio)) {
> -		ret = devm_gpio_request_one(&pdev->dev, imx6_pcie->reset_gpio,
> -					    GPIOF_OUT_INIT_LOW, "PCIe reset");
> -		if (ret) {
> -			dev_err(&pdev->dev, "unable to get reset gpio\n");
> -			return ret;
> -		}
> -	}
> +	imx6_pcie->reset_gpio = devm_gpiod_get_optional(&pdev->dev, "reset",
> +							GPIOD_OUT_LOW);
>  
>  	/* Fetch clocks */
>  	imx6_pcie->pcie_phy = devm_clk_get(&pdev->dev, "pcie_phy");