[PATCH 4/7] gpio: of: Support some legacy Qualcomm HDMI bindings

[Rob Clark]

On Sat, Jun 29, 2019 at 6:02 AM Linus Walleij <linus.walleij at linaro.org> wrote:
>
> Insteaf of the MSM DRM code going around and inspecting the
> device tree nodes by itself to find "qcom,misc" GPIO phandles,
> we add a quirk to the core so that if "qcom,misc-gpios" and
> "qcom,misc-gpio" isn't found, we try to find just
> "qcom,misc" as a last resort. Provide an explicit whitelist
> for those GPIOs.
>
> Cc: Rob Clark <robdclark at gmail.com>
> Cc: Sean Paul <sean at poorly.run>
> Cc: linux-arm-msm at vger.kernel.org
> Cc: freedreno at lists.freedesktop.org
> Signed-off-by: Linus Walleij <linus.walleij at linaro.org>
> ---
> Rob/Sean: if the approach is overall OK I will merge this
> one patch already for v5.3 so the rest can be queued for
> v5.4 later.

I'm ok with this.. although I wonder if we need to try this hard for
backwards compat?  At least I don't see any upstream dts
using the old names.  Maybe it is ok to just look the other way and break them.

IIRC the old names were based on old downstream android kernel
bindings.. but upstream snapdragon support is pretty good these days
and it has been years since I've had to do drm/msm development by
backporting the upstream driver to a crusty old android kernel.

BR,
-R

> ---
>  drivers/gpio/gpiolib-of.c | 43 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 43 insertions(+)
>
> diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
> index aec7bd86ae7e..c927eaf6c88f 100644
> --- a/drivers/gpio/gpiolib-of.c
> +++ b/drivers/gpio/gpiolib-of.c
> @@ -286,6 +286,45 @@ static struct gpio_desc *of_find_regulator_gpio(struct device *dev, const char *
>         return desc;
>  }
>
> +/*
> + * Some non-standard Qualcomm HDMI GPIOs need to be supported as they exist
> + * in random old device trees out there.
> + */
> +static struct gpio_desc *of_find_hdmi_gpio(struct device *dev,
> +                                          const char *con_id,
> +                                          enum of_gpio_flags *of_flags)
> +{
> +       /*
> +        * These are the connection IDs we accept as legacy GPIO phandles.
> +        * If we get here, the same prefix ending with "-gpio" and "-gpios"
> +        * has already been tried so now we finally try with no suffix.
> +        */
> +       const char *whitelist[] = {
> +               "qcom,hdmi-tx-ddc-clk",
> +               "qcom,hdmi-tx-ddc-data",
> +               "qcom,hdmi-tx-hpd",
> +               "qcom,hdmi-tx-mux-en",
> +               "qcom,hdmi-tx-mux-sel",
> +               "qcom,hdmi-tx-mux-lpm",
> +       };
> +       struct device_node *np = dev->of_node;
> +       struct gpio_desc *desc;
> +       int i;
> +
> +       if (!IS_ENABLED(CONFIG_DRM_MSM))
> +               return ERR_PTR(-ENOENT);
> +
> +       if (!con_id)
> +               return ERR_PTR(-ENOENT);
> +
> +       i = match_string(whitelist, ARRAY_SIZE(whitelist), con_id);
> +       if (i < 0)
> +               return ERR_PTR(-ENOENT);
> +
> +       desc = of_get_named_gpiod_flags(np, con_id, 0, of_flags);
> +       return desc;
> +}
> +
>  struct gpio_desc *of_find_gpio(struct device *dev, const char *con_id,
>                                unsigned int idx, unsigned long *flags)
>  {
> @@ -330,6 +369,10 @@ struct gpio_desc *of_find_gpio(struct device *dev, const char *con_id,
>         if (IS_ERR(desc) && PTR_ERR(desc) != -EPROBE_DEFER)
>                 desc = of_find_regulator_gpio(dev, con_id, &of_flags);
>
> +       /* Special handling for HDMI GPIOs if used */
> +       if (IS_ERR(desc) && PTR_ERR(desc) != -EPROBE_DEFER)
> +               desc = of_find_hdmi_gpio(dev, con_id, &of_flags);
> +
>         if (IS_ERR(desc))
>                 return desc;
>
> --
> 2.20.1
>