All of lore.kernel.org
 help / color / mirror / Atom feed
From: Lyude Paul <lyude@redhat.com>
To: intel-gfx@lists.freedesktop.org
Cc: Jani Nikula <jani.nikula@intel.com>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	Sean Paul <seanpaul@chromium.org>,
	Aaron Ma <aaron.ma@canonical.com>,
	Dave Airlie <airlied@redhat.com>,
	dri-devel@lists.freedesktop.org (open list:DRM DRIVERS),
	linux-kernel@vger.kernel.org (open list)
Subject: [PATCH] drm/i915/dpcd_bl: Don't try vesa interface unless specified by VBT
Date: Thu, 18 Mar 2021 13:02:02 -0400	[thread overview]
Message-ID: <20210318170204.513000-1-lyude@redhat.com> (raw)

Looks like that there actually are another subset of laptops on the market
that don't support the Intel HDR backlight interface, but do advertise
support for the VESA DPCD backlight interface despite the fact it doesn't
seem to work.

Note though I'm not entirely clear on this - on one of the machines where
this issue was observed, I also noticed that we appeared to be rejecting
the VBT defined backlight frequency in
intel_dp_aux_vesa_calc_max_backlight(). It's noted in this function that:

/* Use highest possible value of Pn for more granularity of brightness
 * adjustment while satifying the conditions below.
 * ...
 * - FxP is within 25% of desired value.
 *   Note: 25% is arbitrary value and may need some tweak.
 */

So it's possible that this value might just need to be tweaked, but for now
let's just disable the VESA backlight interface unless it's specified in
the VBT just to be safe. We might be able to try enabling this again by
default in the future.

Fixes: 2227816e647a ("drm/i915/dp: Allow forcing specific interfaces through enable_dpcd_backlight")
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Bugzilla: https://gitlab.freedesktop.org/drm/intel/-/issues/3169
Signed-off-by: Lyude Paul <lyude@redhat.com>
---
 drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 1 -
 1 file changed, 1 deletion(-)

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 651884390137..4f8337c7fd2e 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
@@ -646,7 +646,6 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector)
 			break;
 		case INTEL_BACKLIGHT_DISPLAY_DDI:
 			try_intel_interface = true;
-			try_vesa_interface = true;
 			break;
 		default:
 			return -ENODEV;
-- 
2.29.2


WARNING: multiple messages have this Message-ID (diff)
From: Lyude Paul <lyude@redhat.com>
To: intel-gfx@lists.freedesktop.org
Cc: Jani Nikula <jani.nikula@intel.com>,
	open list <linux-kernel@vger.kernel.org>,
	David Airlie <airlied@linux.ie>,
	Sean Paul <seanpaul@chromium.org>,
	"open list:DRM DRIVERS" <dri-devel@lists.freedesktop.org>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>,
	Aaron Ma <aaron.ma@canonical.com>,
	Dave Airlie <airlied@redhat.com>
Subject: [PATCH] drm/i915/dpcd_bl: Don't try vesa interface unless specified by VBT
Date: Thu, 18 Mar 2021 13:02:02 -0400	[thread overview]
Message-ID: <20210318170204.513000-1-lyude@redhat.com> (raw)

Looks like that there actually are another subset of laptops on the market
that don't support the Intel HDR backlight interface, but do advertise
support for the VESA DPCD backlight interface despite the fact it doesn't
seem to work.

Note though I'm not entirely clear on this - on one of the machines where
this issue was observed, I also noticed that we appeared to be rejecting
the VBT defined backlight frequency in
intel_dp_aux_vesa_calc_max_backlight(). It's noted in this function that:

/* Use highest possible value of Pn for more granularity of brightness
 * adjustment while satifying the conditions below.
 * ...
 * - FxP is within 25% of desired value.
 *   Note: 25% is arbitrary value and may need some tweak.
 */

So it's possible that this value might just need to be tweaked, but for now
let's just disable the VESA backlight interface unless it's specified in
the VBT just to be safe. We might be able to try enabling this again by
default in the future.

Fixes: 2227816e647a ("drm/i915/dp: Allow forcing specific interfaces through enable_dpcd_backlight")
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Bugzilla: https://gitlab.freedesktop.org/drm/intel/-/issues/3169
Signed-off-by: Lyude Paul <lyude@redhat.com>
---
 drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 1 -
 1 file changed, 1 deletion(-)

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 651884390137..4f8337c7fd2e 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
@@ -646,7 +646,6 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector)
 			break;
 		case INTEL_BACKLIGHT_DISPLAY_DDI:
 			try_intel_interface = true;
-			try_vesa_interface = true;
 			break;
 		default:
 			return -ENODEV;
-- 
2.29.2

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

WARNING: multiple messages have this Message-ID (diff)
From: Lyude Paul <lyude@redhat.com>
To: intel-gfx@lists.freedesktop.org
Cc: Jani Nikula <jani.nikula@intel.com>,
	open list <linux-kernel@vger.kernel.org>,
	David Airlie <airlied@linux.ie>,
	Sean Paul <seanpaul@chromium.org>,
	"open list:DRM DRIVERS" <dri-devel@lists.freedesktop.org>,
	Aaron Ma <aaron.ma@canonical.com>,
	Dave Airlie <airlied@redhat.com>
Subject: [Intel-gfx] [PATCH] drm/i915/dpcd_bl: Don't try vesa interface unless specified by VBT
Date: Thu, 18 Mar 2021 13:02:02 -0400	[thread overview]
Message-ID: <20210318170204.513000-1-lyude@redhat.com> (raw)

Looks like that there actually are another subset of laptops on the market
that don't support the Intel HDR backlight interface, but do advertise
support for the VESA DPCD backlight interface despite the fact it doesn't
seem to work.

Note though I'm not entirely clear on this - on one of the machines where
this issue was observed, I also noticed that we appeared to be rejecting
the VBT defined backlight frequency in
intel_dp_aux_vesa_calc_max_backlight(). It's noted in this function that:

/* Use highest possible value of Pn for more granularity of brightness
 * adjustment while satifying the conditions below.
 * ...
 * - FxP is within 25% of desired value.
 *   Note: 25% is arbitrary value and may need some tweak.
 */

So it's possible that this value might just need to be tweaked, but for now
let's just disable the VESA backlight interface unless it's specified in
the VBT just to be safe. We might be able to try enabling this again by
default in the future.

Fixes: 2227816e647a ("drm/i915/dp: Allow forcing specific interfaces through enable_dpcd_backlight")
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Bugzilla: https://gitlab.freedesktop.org/drm/intel/-/issues/3169
Signed-off-by: Lyude Paul <lyude@redhat.com>
---
 drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 1 -
 1 file changed, 1 deletion(-)

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 651884390137..4f8337c7fd2e 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
@@ -646,7 +646,6 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector)
 			break;
 		case INTEL_BACKLIGHT_DISPLAY_DDI:
 			try_intel_interface = true;
-			try_vesa_interface = true;
 			break;
 		default:
 			return -ENODEV;
-- 
2.29.2

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

             reply	other threads:[~2021-03-18 17:03 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-18 17:02 Lyude Paul [this message]
2021-03-18 17:02 ` [Intel-gfx] [PATCH] drm/i915/dpcd_bl: Don't try vesa interface unless specified by VBT Lyude Paul
2021-03-18 17:02 ` Lyude Paul
2021-03-18 17:49 ` Lyude Paul
2021-03-18 17:49   ` [Intel-gfx] " Lyude Paul
2021-03-18 17:49   ` Lyude Paul
2021-03-23 14:06   ` Jani Nikula
2021-03-23 14:06     ` [Intel-gfx] " Jani Nikula
2021-03-23 14:06     ` Jani Nikula
2021-03-23 17:19     ` Lyude Paul
2021-03-23 17:19       ` [Intel-gfx] " Lyude Paul
2021-03-23 17:19       ` Lyude Paul
2021-04-06 18:43       ` [Intel-gfx] " Jani Nikula
2021-04-06 18:43         ` Jani Nikula
2021-04-06 18:43         ` Jani Nikula
2021-03-18 19:03 ` [Intel-gfx] ✓ Fi.CI.BAT: success for " Patchwork
2021-03-19  0:27 ` [Intel-gfx] ✓ Fi.CI.IGT: " Patchwork

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210318170204.513000-1-lyude@redhat.com \
    --to=lyude@redhat.com \
    --cc=aaron.ma@canonical.com \
    --cc=airlied@linux.ie \
    --cc=airlied@redhat.com \
    --cc=daniel@ffwll.ch \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=intel-gfx@lists.freedesktop.org \
    --cc=jani.nikula@intel.com \
    --cc=jani.nikula@linux.intel.com \
    --cc=joonas.lahtinen@linux.intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=rodrigo.vivi@intel.com \
    --cc=seanpaul@chromium.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
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.