From b96ab339ee50470d13a1faa6ad94d2218a7cd49f Mon Sep 17 00:00:00 2001 From: Mario Limonciello Date: Wed, 6 Dec 2023 12:08:26 -0600 Subject: [PATCH] drm/amd/display: Restore guard against default backlight value < 1 nit Mark reports that brightness is not restored after Xorg dpms screen blank. This behavior was introduced by commit d9e865826c20 ("drm/amd/display: Simplify brightness initialization") which dropped the cached backlight value in display code, but also removed code for when the default value read back was less than 1 nit. Restore this code so that the backlight brightness is restored to the correct default value in this circumstance. Reported-by: Mark Herbert Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3031 Cc: stable@vger.kernel.org Cc: Camille Cho Cc: Krunoslav Kovac Cc: Hamza Mahfooz Fixes: d9e865826c20 ("drm/amd/display: Simplify brightness initialization") Acked-by: Alex Deucher Signed-off-by: Mario Limonciello Signed-off-by: Alex Deucher --- .../amd/display/dc/link/protocols/link_edp_panel_control.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_edp_panel_control.c b/drivers/gpu/drm/amd/display/dc/link/protocols/link_edp_panel_control.c index 996e4ee99023a8..e5cfaaef70b3f7 100644 --- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_edp_panel_control.c +++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_edp_panel_control.c @@ -287,8 +287,8 @@ bool set_default_brightness_aux(struct dc_link *link) if (link && link->dpcd_sink_ext_caps.bits.oled == 1) { if (!read_default_bl_aux(link, &default_backlight)) default_backlight = 150000; - // if > 5000, it might be wrong readback - if (default_backlight > 5000000) + // if < 1 nits or > 5000, it might be wrong readback + if (default_backlight < 1000 || default_backlight > 5000000) default_backlight = 150000; return edp_set_backlight_level_nits(link, true,