The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x a2020be69490ee8778c59a02e7b270dfeecffbd4 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024012713-dismount-frail-dc0d@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

a2020be69490 ("drm/amd/display: Restore guard against default backlight value < 1 nit") 43b8ac4b34ec ("drm/amd/display: Simplify brightness initialization") 5edb7cdff85a ("drm/amd/display: Reduce default backlight min from 5 nits to 1 nits") 6ec876472ff7 ("drm/amd/display: refactor ILR to make it work")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From a2020be69490ee8778c59a02e7b270dfeecffbd4 Mon Sep 17 00:00:00 2001 From: Mario Limonciello mario.limonciello@amd.com 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 mark.herbert42@gmail.com Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3031 Cc: stable@vger.kernel.org Cc: Camille Cho camille.cho@amd.com Cc: Krunoslav Kovac krunoslav.kovac@amd.com Cc: Hamza Mahfooz hamza.mahfooz@amd.com Fixes: d9e865826c20 ("drm/amd/display: Simplify brightness initialization") Acked-by: Alex Deucher alexander.deucher@amd.com Signed-off-by: Mario Limonciello mario.limonciello@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com

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 ac0fa88b52a0..bf53a86ea817 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,