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drm/panel: simple: Add a comment about unprepare+disable at shutdown/remove

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It's the responsibility of a correctly written DRM modeset driver to
call drm_atomic_helper_shutdown() at shutdown time and that should be
disabling / unpreparing the panel if needed. Panel drivers shouldn't
be calling these functions themselves.

A recent effort was made to fix as many DRM modeset drivers as
possible [1] [2] [3] and most drivers are fixed now.

Unfortunately, it's very difficult to know exactly which DRM modeset
drivers are using panel-simple due to the sheer number of panels it
handles. For now, we'll leave the calls and just add a comment to keep
people from copying this code.

[1] https://lore.kernel.org/r/20230901234015.566018-1-dianders@chromium.org
[2] https://lore.kernel.org/r/20230901234202.566951-1-dianders@chromium.org
[3] https://lore.kernel.org/r/20230921192749.1542462-1-dianders@chromium.org

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240503143327.RFT.v2.27.I639183ac987e139092491a94e22d46a5d857580c@changeid
This commit is contained in:
Douglas Anderson 2024-05-03 14:33:08 -07:00
parent 2a1c99d715
commit bc62654df3
1 changed files with 23 additions and 10 deletions
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33
drivers/gpu/drm/panel/panel-simple.c
View File

@ -716,13 +716,34 @@ free_ddc:
return err;
}
static void panel_simple_shutdown(struct device *dev)
{
struct panel_simple *panel = dev_get_drvdata(dev);
/*
* NOTE: the following two calls don't really belong here. It is the
* responsibility of a correctly written DRM modeset driver to call
* drm_atomic_helper_shutdown() at shutdown time and that should
* cause the panel to be disabled / unprepared if needed. For now,
* however, we'll keep these calls due to the sheer number of
* different DRM modeset drivers used with panel-simple. The fact that
* we're calling these and _also_ the drm_atomic_helper_shutdown()
* will try to disable/unprepare means that we can get a warning about
* trying to disable/unprepare an already disabled/unprepared panel,
* but that's something we'll have to live with until we've confirmed
* that all DRM modeset drivers are properly calling
* drm_atomic_helper_shutdown().
*/
drm_panel_disable(&panel->base);
drm_panel_unprepare(&panel->base);
}
static void panel_simple_remove(struct device *dev)
{
struct panel_simple *panel = dev_get_drvdata(dev);
drm_panel_remove(&panel->base);
drm_panel_disable(&panel->base);
drm_panel_unprepare(&panel->base);
panel_simple_shutdown(dev);
pm_runtime_dont_use_autosuspend(dev);
pm_runtime_disable(dev);
@ -730,14 +751,6 @@ static void panel_simple_remove(struct device *dev)
put_device(&panel->ddc->dev);
}
static void panel_simple_shutdown(struct device *dev)
{
struct panel_simple *panel = dev_get_drvdata(dev);
drm_panel_disable(&panel->base);
drm_panel_unprepare(&panel->base);
}
static const struct drm_display_mode ampire_am_1280800n3tzqw_t00h_mode = {
.clock = 71100,
.hdisplay = 1280,