All of lore.kernel.org
 help / color / mirror / Atom feed
* [PATCH] drm/i915/dp: add a delay before setting panel brightness after power on
@ 2021-09-13 19:35 ` Vasily Khoruzhick
  0 siblings, 0 replies; 16+ messages in thread
From: Vasily Khoruzhick @ 2021-09-13 19:35 UTC (permalink / raw)
  To: Jani Nikula, Joonas Lahtinen, Rodrigo Vivi, David Airlie,
	Daniel Vetter, Lyude Paul, Sean Paul, Aaron Ma, intel-gfx,
	dri-devel
  Cc: Vasily Khoruzhick

Panel in my Dell XPS 7590, that uses Intel's HDR backlight interface to
control brightness, apparently needs a delay before setting brightness
after power on. Without this delay the panel does accept the setting
and may come up with some arbitrary brightness (sometimes it's too dark,
sometimes it's too bright, I wasn't able to find a system).

I don't have access to the spec, so I'm not sure if it's expected
behavior or a quirk for particular device.

Delay was chosen by experiment: it works with 100ms, but fails with
anything lower than 75ms.

Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
---
 drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
index 4f8337c7fd2e..c4f35e1b5870 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
@@ -210,6 +210,10 @@ intel_dp_aux_hdr_enable_backlight(const struct intel_crtc_state *crtc_state,
 
 	ctrl = old_ctrl;
 	if (panel->backlight.edp.intel.sdr_uses_aux) {
+		/* Wait 100ms to ensure that panel is ready otherwise it may not
+		 * set chosen backlight level
+		 */
+		msleep(100);
 		ctrl |= INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE;
 		intel_dp_aux_hdr_set_aux_backlight(conn_state, level);
 	} else {
-- 
2.33.0


^ permalink raw reply related	[flat|nested] 16+ messages in thread

end of thread, other threads:[~2021-09-20  6:58 UTC | newest]

Thread overview: 16+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-09-13 19:35 [PATCH] drm/i915/dp: add a delay before setting panel brightness after power on Vasily Khoruzhick
2021-09-13 19:35 ` [Intel-gfx] " Vasily Khoruzhick
2021-09-13 22:34 ` [Intel-gfx] ✓ Fi.CI.BAT: success for " Patchwork
2021-09-14  1:58 ` [Intel-gfx] ✓ Fi.CI.IGT: " Patchwork
2021-09-14  9:09 ` [PATCH] " Jani Nikula
2021-09-14  9:09   ` [Intel-gfx] " Jani Nikula
2021-09-14 21:08   ` Lyude Paul
2021-09-14 21:08     ` [Intel-gfx] " Lyude Paul
2021-09-14 22:31     ` Jani Nikula
2021-09-14 22:31       ` [Intel-gfx] " Jani Nikula
2021-09-15  1:10       ` Vasily Khoruzhick
2021-09-15  1:10         ` [Intel-gfx] " Vasily Khoruzhick
2021-09-15  8:47         ` Jani Nikula
2021-09-15  8:47           ` [Intel-gfx] " Jani Nikula
2021-09-20  6:57           ` Vasily Khoruzhick
2021-09-20  6:57             ` [Intel-gfx] " Vasily Khoruzhick

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.