[PATCH 2/5] drm/i915: keep AUX powered while PSR is enabled

["José Roberto de Souza" <jose.souza@intel.com>]

Hardware can send AUX transactions by it self when PSR is enabled and it
expects that AUX is kept powered up.

From spec:

"Each DisplayPort Aux channel has an Aux IO Power Request. If an Aux
channel will not be used, it does not need to be powered up.

PSR spontaneously sends Aux transactions.  If PSR is enabled on a port,
then the associated Aux IO must be kept powered up."

BSpec: 4230
BSpec: 17722

Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
---
 drivers/gpu/drm/i915/intel_psr.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
index 8b456e4e1b47..225fde979e57 100644
--- a/drivers/gpu/drm/i915/intel_psr.c
+++ b/drivers/gpu/drm/i915/intel_psr.c
@@ -516,6 +516,12 @@ void intel_psr_enable(struct intel_dp *intel_dp,
 		goto unlock;
 	}
 
+	/*
+	 * hardware can send AUX transactions by it self when PSR is enabled,
+	 * and it expects that AUX is kept powered up.
+	 */
+	intel_display_power_get(dev_priv, intel_dp->aux_power_domain);
+
 	dev_priv->psr.psr2_support = crtc_state->has_psr2;
 	dev_priv->psr.busy_frontbuffer_bits = 0;
 
@@ -656,6 +662,8 @@ void intel_psr_disable(struct intel_dp *intel_dp,
 	/* Disable PSR on Sink */
 	drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG, 0);
 
+	intel_display_power_put(dev_priv, intel_dp->aux_power_domain);
+
 	dev_priv->psr.enabled = NULL;
 	mutex_unlock(&dev_priv->psr.lock);
 
-- 
2.16.1

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