From bc62654df3c888dec735343f5db9907ac93aea60 Mon Sep 17 00:00:00 2001
From: Douglas Anderson <dianders@chromium.org>
Date: Fri, 3 May 2024 14:33:08 -0700
Subject: [PATCH] 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: 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
---
drivers/gpu/drm/panel/panel-simple.c | 33 +++++++++++++++++++---------
1 file changed, 23 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index df32284fa293e..9b9e078ec8aa5 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -716,26 +716,39 @@ free_ddc:
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 = {
--
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