[PATCH v2 2/3] drm/i915/dp: Track source OUI validity explicitly

[Imre Deak]

While updating the source OUI on the sink the driver should avoid
writing the OUI if it's already up-to-date to prevent the sink from
resetting itself in response to the update. On eDP - the only output
type where the OUI was updated so far - the driver ensured this by
comparing the current source OUI DPCD register values with the expected
Intel OUI value, skipping the update in case of a match. On some non-eDP
sinks - at least on Synaptics branch devices - this method doesn't work,
since the source OUI DPCD registers read back as all 0, even after
updating the registers.

Handle the above kind of sinks by tracking when the OUI was updated and
so should be valid, regardless of what the DPCD registers contain.

This is required by the next patch updating the source OUI on non-eDP
sink types as well.

Signed-off-by: Imre Deak <imre.deak at intel.com>
---
 drivers/gpu/drm/i915/display/g4x_dp.c         |  1 +
 drivers/gpu/drm/i915/display/intel_ddi.c      |  1 +
 .../drm/i915/display/intel_display_types.h    |  1 +
 drivers/gpu/drm/i915/display/intel_dp.c       | 25 ++++++++++++++-----
 drivers/gpu/drm/i915/display/intel_dp.h       |  1 +
 5 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/g4x_dp.c b/drivers/gpu/drm/i915/display/g4x_dp.c
index 440fb3002f286..596e926ef0894 100644
--- a/drivers/gpu/drm/i915/display/g4x_dp.c
+++ b/drivers/gpu/drm/i915/display/g4x_dp.c
@@ -1251,6 +1251,7 @@ static void intel_dp_encoder_reset(struct drm_encoder *encoder)
 	intel_dp->DP = intel_de_read(display, intel_dp->output_reg);
 
 	intel_dp->reset_link_params = true;
+	intel_dp_invalidate_source_oui(intel_dp);
 
 	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
 		vlv_pps_pipe_reset(intel_dp);
diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
index fe1ded6707f90..465f245a53c48 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.c
+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
@@ -4392,6 +4392,7 @@ static void intel_ddi_encoder_reset(struct drm_encoder *encoder)
 	struct intel_digital_port *dig_port = enc_to_dig_port(to_intel_encoder(encoder));
 
 	intel_dp->reset_link_params = true;
+	intel_dp_invalidate_source_oui(intel_dp);
 
 	intel_pps_encoder_reset(intel_dp);
 
diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index 7ff97e5b83dd5..ad84ffa31c97f 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -1757,6 +1757,7 @@ struct intel_dp {
 
 	/* When we last wrote the OUI for eDP */
 	unsigned long last_oui_write;
+	bool oui_valid;
 
 	bool colorimetry_support;
 
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index b7661529f1927..2d6ffbeae07a0 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -3335,31 +3335,43 @@ void intel_dp_sink_disable_decompression(struct intel_atomic_state *state,
 }
 
 static void
-intel_edp_init_source_oui(struct intel_dp *intel_dp, bool careful)
+intel_dp_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] = {};
 
+	if (!intel_dp_is_edp(intel_dp))
+		return;
+
 	/*
 	 * During driver init, we want to be careful and avoid changing the source OUI if it's
 	 * already set to what we want, so as to avoid clearing any state by accident
 	 */
-	if (careful) {
+	if (!intel_dp->oui_valid) {
 		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) {
 			/* Assume the OUI was written now. */
 			intel_dp->last_oui_write = jiffies;
-			return;
+			intel_dp->oui_valid = true;
 		}
 	}
 
+	if (intel_dp->oui_valid)
+		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");
 
 	intel_dp->last_oui_write = jiffies;
+	intel_dp->oui_valid = true;
+}
+
+void intel_dp_invalidate_source_oui(struct intel_dp *intel_dp)
+{
+	intel_dp->oui_valid = false;
 }
 
 void intel_dp_wait_source_oui(struct intel_dp *intel_dp)
@@ -3390,6 +3402,8 @@ void intel_dp_set_power(struct intel_dp *intel_dp, u8 mode)
 		if (downstream_hpd_needs_d0(intel_dp))
 			return;
 
+		intel_dp_invalidate_source_oui(intel_dp);
+
 		ret = drm_dp_dpcd_writeb(&intel_dp->aux, DP_SET_POWER, mode);
 	} else {
 		struct intel_lspcon *lspcon = dp_to_lspcon(intel_dp);
@@ -3397,8 +3411,7 @@ void intel_dp_set_power(struct intel_dp *intel_dp, u8 mode)
 		lspcon_resume(dp_to_dig_port(intel_dp));
 
 		/* Write the source OUI as early as possible */
-		if (intel_dp_is_edp(intel_dp))
-			intel_edp_init_source_oui(intel_dp, false);
+		intel_dp_init_source_oui(intel_dp);
 
 		/*
 		 * When turning on, we need to retry for 1ms to give the sink
@@ -4115,7 +4128,7 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp, struct intel_connector *connector
 	 * If needed, 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, true);
+	intel_dp_init_source_oui(intel_dp);
 
 	return true;
 }
diff --git a/drivers/gpu/drm/i915/display/intel_dp.h b/drivers/gpu/drm/i915/display/intel_dp.h
index 3b869429e5756..0449d1d3f175d 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.h
+++ b/drivers/gpu/drm/i915/display/intel_dp.h
@@ -189,6 +189,7 @@ void intel_dp_check_frl_training(struct intel_dp *intel_dp);
 void intel_dp_pcon_dsc_configure(struct intel_dp *intel_dp,
 				 const struct intel_crtc_state *crtc_state);
 
+void intel_dp_invalidate_source_oui(struct intel_dp *intel_dp);
 void intel_dp_wait_source_oui(struct intel_dp *intel_dp);
 int intel_dp_output_bpp(enum intel_output_format output_format, int bpp);
 
-- 
2.44.2