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From 19a69eeab6e384399f2ba99945dffc613d744ca1 Mon Sep 17 00:00:00 2001
From: Lyude Paul <lyude@redhat.com>
Date: Fri, 26 Jun 2020 17:53:48 -0400
Subject: [PATCH 1/2] drm/i915/dp: Program source OUI on eDP panels
Since we're about to start adding support for Intel's magic HDR
backlight interface over DPCD, we need to ensure we're properly
programming this field so that Intel specific sink services are exposed.
Otherwise, 0x300-0x3ff will just read zeroes.
We also take care not to reprogram the source OUI if it already matches
what we expect. This is just to be careful so that we don't accidentally
take the panel out of any backlight control modes we found it in.
Signed-off-by: Lyude Paul <lyude@redhat.com>
---
drivers/gpu/drm/i915/display/intel_dp.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index d6295eb20b63..39667264c27d 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -4554,6 +4554,25 @@ static void intel_dp_get_dsc_sink_cap(struct intel_dp *intel_dp)
}
}
+static void
+intel_edp_init_source_oui(struct intel_dp *intel_dp)
+{
+ struct drm_i915_private *i915 = dp_to_i915(intel_dp);
+ u8 oui[] = { 0x00, 0xaa, 0x01 };
+ u8 buf[3] = { 0 };
+
+ if (drm_dp_dpcd_read(&intel_dp->aux, DP_SOURCE_OUI, buf,
+ sizeof(buf)) < 0)
+ drm_err(&i915->drm, "Failed to read source OUI\n");
+
+ if (memcmp(oui, buf, sizeof(oui)) == 0)
+ return;
+
+ if (drm_dp_dpcd_write(&intel_dp->aux, DP_SOURCE_OUI, oui,
+ sizeof(oui)) < 0)
+ drm_err(&i915->drm, "Failed to write source OUI\n");
+}
+
static bool
intel_edp_init_dpcd(struct intel_dp *intel_dp)
{
@@ -4631,6 +4650,12 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp)
if (INTEL_GEN(dev_priv) >= 10 || IS_GEMINILAKE(dev_priv))
intel_dp_get_dsc_sink_cap(intel_dp);
+ /*
+ * Program our source OUI so we can make various Intel-specific AUX
+ * services available (such as HDR backlight controls)
+ */
+ intel_edp_init_source_oui(intel_dp);
+
return true;
}
--
2.28.0
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