drm/i915: Get HDR DPCD refresh timeout from VBT

Grab the HDR DPCD refresh timeout (time we need to wait after
writing the sourc OUI before the HDR DPCD registers are ready)
from the VBT.

Windows doesn't even seem to have any default value for this,
which is perhaps a bit weird since the VBT value is documented
as TGL+ and I thought the HDR backlight stuff might already be
used on earlier platforms. To play it safe I left the old
hardcoded 30ms default in place. Digging through some internal
stuff that seems to have been a number given by the vendor for
one particularly slow TCON. Although I did see 50ms mentioned
somewhere as well.

Let's also include the value in the debug print to ease
debugging, and toss in the customary connector id+name as well.

The TGL Thinkpad T14 I have sets this to 0 btw. So the delay
is now gone on this machine:
 [CONNECTOR:308:eDP-1] Detected Intel HDR backlight interface version 1
 [CONNECTOR:308:eDP-1] Using Intel proprietary eDP backlight controls
 [CONNECTOR:308:eDP-1] SDR backlight is controlled through PWM
 [CONNECTOR:308:eDP-1] Using native PCH PWM for backlight control (controller=0)
 [CONNECTOR:308:eDP-1] Using AUX HDR interface for backlight control (range 0..496)
 [CONNECTOR:308:eDP-1] Performing OUI wait (0 ms)

Cc: Lyude Paul <lyude@redhat.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230220164718.23117-1-ville.syrjala@linux.intel.com
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>

3 files changed, 14 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
index f35ef3675d39..f16887aed56d 100644
--- a/drivers/gpu/drm/i915/display/intel_bios.c
+++ b/drivers/gpu/drm/i915/display/intel_bios.c
@@ -1084,6 +1084,12 @@ parse_lfp_backlight(struct drm_i915_private *i915,
 		panel->vbt.backlight.min_brightness = entry->min_brightness;
 	}
 
+	if (i915->display.vbt.version >= 239)
+		panel->vbt.backlight.hdr_dpcd_refresh_timeout =
+			DIV_ROUND_UP(backlight_data->hdr_dpcd_refresh_timeout[panel_type], 100);
+	else
+		panel->vbt.backlight.hdr_dpcd_refresh_timeout = 30;
+
 	drm_dbg_kms(&i915->drm,
 		    "VBT backlight PWM modulation frequency %u Hz, "
 		    "active %s, min brightness %u, level %u, controller %u\n",
diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index 22de8f57b354..c32bfba06ca1 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -326,6 +326,7 @@ struct intel_vbt_panel_data {
 	struct {
 		u16 pwm_freq_hz;
 		u16 brightness_precision_bits;
+		u16 hdr_dpcd_refresh_timeout;
 		bool present;
 		bool active_low_pwm;
 		u8 min_brightness;	/* min_brightness/255 of max */
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index d25a93258f8b..aee93b0d810e 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -2292,10 +2292,15 @@ intel_edp_init_source_oui(struct intel_dp *intel_dp, bool careful)
 
 void intel_dp_wait_source_oui(struct intel_dp *intel_dp)
 {
+	struct intel_connector *connector = intel_dp->attached_connector;
 	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
 
-	drm_dbg_kms(&i915->drm, "Performing OUI wait\n");
-	wait_remaining_ms_from_jiffies(intel_dp->last_oui_write, 30);
+	drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] Performing OUI wait (%u ms)\n",
+		    connector->base.base.id, connector->base.name,
+		    connector->panel.vbt.backlight.hdr_dpcd_refresh_timeout);
+
+	wait_remaining_ms_from_jiffies(intel_dp->last_oui_write,
+				       connector->panel.vbt.backlight.hdr_dpcd_refresh_timeout);
 }
 
 /* If the device supports it, try to set the power state appropriately */