Re: [PATCH v8 1/4] drm/panel: Add helper for reading DT rotation

From: Sean Paul
Date: Mon Oct 07 2019 - 12:38:26 EST


On Wed, Sep 25, 2019 at 03:58:30PM -0700, Derek Basehore wrote:
> This adds a helper function for reading the rotation (panel
> orientation) from the device tree.
>
> Signed-off-by: Derek Basehore <dbasehore@xxxxxxxxxxxx>
> Reviewed-by: Sam Ravnborg <sam@xxxxxxxxxxxx>

The patch LGTM, but I don't see it used anywhere later in the patch? Is there a
panel driver incoming?

Sean

> ---
> drivers/gpu/drm/drm_panel.c | 43 +++++++++++++++++++++++++++++++++++++
> include/drm/drm_panel.h | 9 ++++++++
> 2 files changed, 52 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
> index 6b0bf42039cf..0909b53b74e6 100644
> --- a/drivers/gpu/drm/drm_panel.c
> +++ b/drivers/gpu/drm/drm_panel.c
> @@ -264,6 +264,49 @@ struct drm_panel *of_drm_find_panel(const struct device_node *np)
> return ERR_PTR(-EPROBE_DEFER);
> }
> EXPORT_SYMBOL(of_drm_find_panel);
> +
> +/**
> + * of_drm_get_panel_orientation - look up the orientation of the panel through
> + * the "rotation" binding from a device tree node
> + * @np: device tree node of the panel
> + * @orientation: orientation enum to be filled in
> + *
> + * Looks up the rotation of a panel in the device tree. The orientation of the
> + * panel is expressed as a property name "rotation" in the device tree. The
> + * rotation in the device tree is counter clockwise.
> + *
> + * Return: 0 when a valid rotation value (0, 90, 180, or 270) is read or the
> + * rotation property doesn't exist. -EERROR otherwise.
> + */
> +int of_drm_get_panel_orientation(const struct device_node *np,
> + enum drm_panel_orientation *orientation)
> +{
> + int rotation, ret;
> +
> + ret = of_property_read_u32(np, "rotation", &rotation);
> + if (ret == -EINVAL) {
> + /* Don't return an error if there's no rotation property. */
> + *orientation = DRM_MODE_PANEL_ORIENTATION_UNKNOWN;
> + return 0;
> + }
> +
> + if (ret < 0)
> + return ret;
> +
> + if (rotation == 0)
> + *orientation = DRM_MODE_PANEL_ORIENTATION_NORMAL;
> + else if (rotation == 90)
> + *orientation = DRM_MODE_PANEL_ORIENTATION_RIGHT_UP;
> + else if (rotation == 180)
> + *orientation = DRM_MODE_PANEL_ORIENTATION_BOTTOM_UP;
> + else if (rotation == 270)
> + *orientation = DRM_MODE_PANEL_ORIENTATION_LEFT_UP;
> + else
> + return -EINVAL;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(of_drm_get_panel_orientation);
> #endif
>
> MODULE_AUTHOR("Thierry Reding <treding@xxxxxxxxxx>");
> diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h
> index 624bd15ecfab..d16158deacdc 100644
> --- a/include/drm/drm_panel.h
> +++ b/include/drm/drm_panel.h
> @@ -34,6 +34,8 @@ struct drm_device;
> struct drm_panel;
> struct display_timing;
>
> +enum drm_panel_orientation;
> +
> /**
> * struct drm_panel_funcs - perform operations on a given panel
> *
> @@ -165,11 +167,18 @@ int drm_panel_get_modes(struct drm_panel *panel);
>
> #if defined(CONFIG_OF) && defined(CONFIG_DRM_PANEL)
> struct drm_panel *of_drm_find_panel(const struct device_node *np);
> +int of_drm_get_panel_orientation(const struct device_node *np,
> + enum drm_panel_orientation *orientation);
> #else
> static inline struct drm_panel *of_drm_find_panel(const struct device_node *np)
> {
> return ERR_PTR(-ENODEV);
> }
> +static inline int of_drm_get_panel_orientation(const struct device_node *np,
> + enum drm_panel_orientation *orientation)
> +{
> + return -ENODEV;
> +}
> #endif
>
> #endif
> --
> 2.23.0.351.gc4317032e6-goog
>

--
Sean Paul, Software Engineer, Google / Chromium OS