Commit bc62654d authored by Douglas Anderson's avatar Douglas Anderson
Browse files

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

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: default avatarLinus Walleij <linus.walleij@linaro.org>
Acked-by: default avatarMaxime Ripard <mripard@kernel.org>
Signed-off-by: default avatarDouglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240503143327.RFT.v2.27.I639183ac987e139092491a94e22d46a5d857580c@changeid
parent 2a1c99d7

drivers/gpu/drm/panel/panel-simple.c

+23 −10
Original line number Diff line number Diff line
@@ -716,26 +716,39 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc) 
	return err;

}



static void panel_simple_remove(struct device *dev)

static void panel_simple_shutdown(struct device *dev)

{

	struct panel_simple *panel = dev_get_drvdata(dev);



	drm_panel_remove(&panel->base);

	/*

	 * 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);



	pm_runtime_dont_use_autosuspend(dev);

	pm_runtime_disable(dev);

	if (panel->ddc)

		put_device(&panel->ddc->dev);

}



static void panel_simple_shutdown(struct device *dev)

static void panel_simple_remove(struct device *dev)

{

	struct panel_simple *panel = dev_get_drvdata(dev);



	drm_panel_disable(&panel->base);

	drm_panel_unprepare(&panel->base);

	drm_panel_remove(&panel->base);

	panel_simple_shutdown(dev);



	pm_runtime_dont_use_autosuspend(dev);

	pm_runtime_disable(dev);

	if (panel->ddc)

		put_device(&panel->ddc->dev);

}



static const struct drm_display_mode ampire_am_1280800n3tzqw_t00h_mode = {