drm/i915/psr: Check for SET_POWER_CAPABLE bit at PSR init time.

By moving the check from psr_compute_config() to psr_init_dpcd(), we get
to set the dev_priv->psr.sink_support flag only when the panel is
capable of changing power state. An additional benefit is that the check
will be performed only at init time instead of every atomic_check.

This should change the psr_basic IGT failures on HSW to skips.

v2: Return early when SET_POWER_CAPABLE bit is 0 (Jose)

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=106217
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=106346
Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180511195145.3829-2-dhinakaran.pandiyan@intel.com

drivers/gpu/drm/i915/intel_dp.c

@@ -3730,8 +3730,6 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp)
 		dev_priv->no_aux_handshake = intel_dp->dpcd[DP_MAX_DOWNSPREAD] &
 			DP_NO_AUX_HANDSHAKE_LINK_TRAINING;
 
-	intel_psr_init_dpcd(intel_dp);
-
 	/*
 	 * Read the eDP display control registers.
 	 *
@@ -3747,6 +3745,12 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp)
 		DRM_DEBUG_KMS("eDP DPCD: %*ph\n", (int) sizeof(intel_dp->edp_dpcd),
 			      intel_dp->edp_dpcd);
 
+	/*
+	 * This has to be called after intel_dp->edp_dpcd is filled, PSR checks
+	 * for SET_POWER_CAPABLE bit in intel_dp->edp_dpcd[1]
+	 */
+	intel_psr_init_dpcd(intel_dp);
+
 	/* Read the eDP 1.4+ supported link rates. */
 	if (intel_dp->edp_dpcd[0] >= DP_EDP_14) {
 		__le16 sink_rates[DP_MAX_SUPPORTED_RATES];

drivers/gpu/drm/i915/intel_psr.c

@@ -248,9 +248,13 @@ void intel_psr_init_dpcd(struct intel_dp *intel_dp)
 
 	if (!intel_dp->psr_dpcd[0])
 		return;
-
 	DRM_DEBUG_KMS("eDP panel supports PSR version %x\n",
 		      intel_dp->psr_dpcd[0]);
+
+	if (!(intel_dp->edp_dpcd[1] & DP_EDP_SET_POWER_CAP)) {
+		DRM_DEBUG_KMS("Panel lacks power state control, PSR cannot be enabled\n");
+		return;
+	}
 	dev_priv->psr.sink_support = true;
 
 	if (INTEL_GEN(dev_priv) >= 9 &&
@@ -570,11 +574,6 @@ void intel_psr_compute_config(struct intel_dp *intel_dp,
 		return;
 	}
 
-	if (!(intel_dp->edp_dpcd[1] & DP_EDP_SET_POWER_CAP)) {
-		DRM_DEBUG_KMS("PSR condition failed: panel lacks power state control\n");
-		return;
-	}
-
 	crtc_state->has_psr = true;
 	crtc_state->has_psr2 = intel_psr2_config_valid(intel_dp, crtc_state);
 	DRM_DEBUG_KMS("Enabling PSR%s\n", crtc_state->has_psr2 ? "2" : "");