On Mon, 2020-10-12 at 13:50 -0400, Sean Paul wrote:
On Tue, Sep 22, 2020 at 11:36 AM Lyude Paul lyude@redhat.com wrote:
On Tue, 2020-09-22 at 09:39 -0400, Sean Paul wrote:
On Mon, Sep 21, 2020 at 6:35 PM Lyude Paul lyude@redhat.com wrote:
So if I understand this correctly, it sounds like that some Pixelbooks boot up with DP_EDP_BACKLIGHT_BRIGHTNESS_MSB set to a non-zero value, without the panel actually having DPCD backlight controls enabled?
It boots with DP_EDP_BACKLIGHT_BRIGHTNESS_MSB == 0, which used to set backlight.enabled = false. By changing backlight.level = max, backlight.enabled is now set to true. This results in losing backlight control on boot (since the enable routine is no longer invoked).
Ahhh ok, I'm fine with that - review still stands :)
Pinging intel maintainers, could someone please apply this?
oops, sorry about that. I can go ahead and push this
Sean
Sean
If I'm understanding that correctly, then this patch looks good to me:
Reviewed-by: Lyude Paul lyude@redhat.com
On Thu, 2020-09-17 at 20:28 -0400, Sean Paul wrote:
From: Sean Paul seanpaul@chromium.org
In commit 79946723092b ("drm/i915: Assume 100% brightness when not in DPCD control mode"), we fixed the brightness level when DPCD control was not active to max brightness. This is as good as we can guess since most backlights go on full when uncontrolled.
However in doing so we changed the semantics of the initial 'backlight.enabled' value. At least on Pixelbooks, they were relying on the brightness level in DP_EDP_BACKLIGHT_BRIGHTNESS_MSB to be 0 on boot such that enabled would be false. This causes the device to be enabled when the brightness is set. Without this, brightness control doesn't work. So by changing brightness to max, we also flipped enabled to be true on boot.
To fix this, make enabled a function of brightness and backlight control mechanism.
Fixes: 79946723092b ("drm/i915: Assume 100% brightness when not in DPCD control mode") Cc: Lyude Paul lyude@redhat.com Cc: Jani Nikula jani.nikula@intel.com Cc: Juha-Pekka Heikkila juhapekka.heikkila@gmail.com Cc: "Ville Syrjälä" ville.syrjala@linux.intel.com Cc: Rodrigo Vivi rodrigo.vivi@intel.com Cc: Kevin Chowski chowski@chromium.org> Signed-off-by: Sean Paul seanpaul@chromium.org
.../drm/i915/display/intel_dp_aux_backlight.c | 31 ++++++++++++----
1 file changed, 20 insertions(+), 11 deletions(-)
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 acbd7eb66cbe..036f504ac7db 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c @@ -52,17 +52,11 @@ static void set_aux_backlight_enable(struct intel_dp *intel_dp, bool enable) } }
-/*
- Read the current backlight value from DPCD register(s) based
- on if 8-bit(MSB) or 16-bit(MSB and LSB) values are supported
- */
-static u32 intel_dp_aux_get_backlight(struct intel_connector *connector) +static bool intel_dp_aux_backlight_dpcd_mode(struct intel_connector *connector) { struct intel_dp *intel_dp = intel_attached_dp(connector); struct drm_i915_private *i915 = dp_to_i915(intel_dp);
u8 read_val[2] = { 0x0 }; u8 mode_reg;u16 level = 0; if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER,@@ -70,15 +64,29 @@ static u32 intel_dp_aux_get_backlight(struct intel_connector *connector) drm_dbg_kms(&i915->drm, "Failed to read the DPCD register 0x%x\n", DP_EDP_BACKLIGHT_MODE_SET_REGISTER);
return 0;
return false; }return (mode_reg & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK) ==DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;+}
+/*
- Read the current backlight value from DPCD register(s) based
- on if 8-bit(MSB) or 16-bit(MSB and LSB) values are supported
- */
+static u32 intel_dp_aux_get_backlight(struct intel_connector *connector) +{
struct intel_dp *intel_dp = intel_attached_dp(connector);struct drm_i915_private *i915 = dp_to_i915(intel_dp);u8 read_val[2] = { 0x0 };u16 level = 0;/* * If we're not in DPCD control mode yet, the programmedbrightness * value is meaningless and we should assume max brightness */
if ((mode_reg & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK) !=DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD)
if (!intel_dp_aux_backlight_dpcd_mode(connector)) return connector->panel.backlight.max; if (drm_dp_dpcd_read(&intel_dp->aux,DP_EDP_BACKLIGHT_BRIGHTNESS_MSB, @@ -319,7 +327,8 @@ static int intel_dp_aux_setup_backlight(struct intel_connector *connector,
panel->backlight.min = 0; panel->backlight.level = intel_dp_aux_get_backlight(connector);
panel->backlight.enabled = panel->backlight.level != 0;
panel->backlight.enabled =intel_dp_aux_backlight_dpcd_mode(connector) &&
panel->backlight.level != 0; return 0;}
-- Cheers, Lyude Paul (she/her) Software Engineer at Red Hat
-- Cheers, Lyude Paul (she/her) Software Engineer at Red Hat