Re: [PATCH 3/5] drm/panel: Add attach/detach callbacks

Daniel Vetter
2019-06-11T08:57:22Z

On Mon, Jun 10, 2019 at 09:03:48PM -0700, Derek Basehore wrote:
> This adds the attach/detach callbacks. These are for setting up
> internal state for the connector/panel pair that can't be done at
> probe (since the connector doesn't exist) and which don't need to be
> repeatedly done for every get/modes, prepare, or enable callback.
> Values such as the panel orientation, and display size can be filled
> in for the connector.
>
> Signed-off-by: Derek Basehore <dbasehore@chromium.org>
> ---
> drivers/gpu/drm/drm_panel.c | 14 ++++++++++++++
> include/drm/drm_panel.h | 4 ++++
> 2 files changed, 18 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
> index 3b689ce4a51a..72f67678d9d5 100644
> --- a/drivers/gpu/drm/drm_panel.c
> +++ b/drivers/gpu/drm/drm_panel.c
> @@ -104,12 +104,23 @@ EXPORT_SYMBOL(drm_panel_remove);
> */
> int drm_panel_attach(struct drm_panel *panel, struct drm_connector *connector)
> {
> + int ret;
> +
> if (panel->connector)
> return -EBUSY;
>
> panel->connector = connector;
> panel->drm = connector->dev;
>
> + if (panel->funcs->attach) {
> + ret = panel->funcs->attach(panel);
> + if (ret < 0) {
> + panel->connector = NULL;
> + panel->drm = NULL;
> + return ret;
> + }
> + }

Why can't we just implement this in the drm helpers for everyone, by e.g.
storing a dt node in drm_panel? Feels a bit overkill to have these new
hooks here.

Also, my understanding is that this dt stuff is supposed to be
standardized, so this should work.
-Daniel

> +
> return 0;
> }
> EXPORT_SYMBOL(drm_panel_attach);
> @@ -128,6 +139,9 @@ EXPORT_SYMBOL(drm_panel_attach);
> */
> int drm_panel_detach(struct drm_panel *panel)
> {
> + if (panel->funcs->detach)
> + panel->funcs->detach(panel);
> +
> panel->connector = NULL;
> panel->drm = NULL;
>
> diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h
> index 13631b2efbaa..e136e3a3c996 100644
> --- a/include/drm/drm_panel.h
> +++ b/include/drm/drm_panel.h
> @@ -37,6 +37,8 @@ struct display_timing;
> * struct drm_panel_funcs - perform operations on a given panel
> * @disable: disable panel (turn off back light, etc.)
> * @unprepare: turn off panel
> + * @detach: detach panel->connector (clear internal state, etc.)
> + * @attach: attach panel->connector (update internal state, etc.)
> * @prepare: turn on panel and perform set up
> * @enable: enable panel (turn on back light, etc.)
> * @get_modes: add modes to the connector that the panel is attached to and
> @@ -70,6 +72,8 @@ struct display_timing;
> struct drm_panel_funcs {
> int (*disable)(struct drm_panel *panel);
> int (*unprepare)(struct drm_panel *panel);
> + void (*detach)(struct drm_panel *panel);
> + int (*attach)(struct drm_panel *panel);
> int (*prepare)(struct drm_panel *panel);
> int (*enable)(struct drm_panel *panel);
> int (*get_modes)(struct drm_panel *panel);
> --
> 2.22.0.rc2.383.gf4fbbf30c2-goog
>

--
Daniel Vetter
Software Engineer, Intel Corporation