Sink can be configured to calculate the CRC over the static frame and
compare with the CRC calculated and transmited in the VSC SDP by
source, if there is a mismatch sink will do a short pulse in HPD
and set DP_PSR_LINK_CRC_ERROR on DP_PSR_ERROR_STATUS.

Also spec recommends to disable MAX_SLEEP as a trigger to exit PSR when
CRC check is enabled to improve power savings.

Spec: 7723

v3:
disabling PSR instead of exiting on error

Cc: Dhinakaran Pandiyan <dhinakaran.pandi...@intel.com>
Cc: Rodrigo Vivi <rodrigo.v...@intel.com>
Signed-off-by: José Roberto de Souza <jose.so...@intel.com>
---
 drivers/gpu/drm/i915/i915_reg.h  |  1 +
 drivers/gpu/drm/i915/intel_psr.c | 29 ++++++++++++++++++++---------
 2 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 196a0eb79272..1add22e664ea 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -4020,6 +4020,7 @@ enum {
 #define   EDP_PSR_SKIP_AUX_EXIT                        (1<<12)
 #define   EDP_PSR_TP1_TP2_SEL                  (0<<11)
 #define   EDP_PSR_TP1_TP3_SEL                  (1<<11)
+#define   EDP_PSR_CRC_ENABLE                   (1<<10) /* BDW+ */
 #define   EDP_PSR_TP2_TP3_TIME_500us           (0<<8)
 #define   EDP_PSR_TP2_TP3_TIME_100us           (1<<8)
 #define   EDP_PSR_TP2_TP3_TIME_2500us          (2<<8)
diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
index f72e3f91809f..2f29dcd6f69e 100644
--- a/drivers/gpu/drm/i915/intel_psr.c
+++ b/drivers/gpu/drm/i915/intel_psr.c
@@ -363,6 +363,8 @@ static void hsw_psr_enable_sink(struct intel_dp *intel_dp)
                dpcd_val |= DP_PSR_ENABLE_PSR2;
        if (dev_priv->psr.link_standby)
                dpcd_val |= DP_PSR_MAIN_LINK_ACTIVE;
+       if (!dev_priv->psr.psr2_enabled && INTEL_GEN(dev_priv) >= 8)
+               dpcd_val |= DP_PSR_CRC_VERIFICATION;
        drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG, dpcd_val);
 
        drm_dp_dpcd_writeb(&intel_dp->aux, DP_SET_POWER, DP_SET_POWER_D0);
@@ -418,6 +420,9 @@ static void hsw_activate_psr1(struct intel_dp *intel_dp)
        else
                val |= EDP_PSR_TP1_TP2_SEL;
 
+       if (INTEL_GEN(dev_priv) >= 8)
+               val |= EDP_PSR_CRC_ENABLE;
+
        val |= I915_READ(EDP_PSR_CTL) & EDP_PSR_RESTORE_PSR_ACTIVE_CTX_MASK;
        I915_WRITE(EDP_PSR_CTL, val);
 }
@@ -635,11 +640,14 @@ static void hsw_psr_enable_source(struct intel_dp 
*intel_dp,
                 * preventing  other hw tracking issues now we can rely
                 * on frontbuffer tracking.
                 */
-               I915_WRITE(EDP_PSR_DEBUG,
-                          EDP_PSR_DEBUG_MASK_MEMUP |
-                          EDP_PSR_DEBUG_MASK_HPD |
-                          EDP_PSR_DEBUG_MASK_LPSP |
-                          EDP_PSR_DEBUG_MASK_DISP_REG_WRITE);
+               u32 val = EDP_PSR_DEBUG_MASK_MEMUP |
+                         EDP_PSR_DEBUG_MASK_HPD |
+                         EDP_PSR_DEBUG_MASK_LPSP |
+                         EDP_PSR_DEBUG_MASK_DISP_REG_WRITE;
+
+               if (INTEL_GEN(dev_priv) >= 8)
+                       val |= EDP_PSR_DEBUG_MASK_MAX_SLEEP;
+               I915_WRITE(EDP_PSR_DEBUG, val);
        }
 }
 
@@ -1051,16 +1059,19 @@ void intel_psr_short_pulse(struct intel_dp *intel_dp)
                goto exit;
        }
 
-       if (val & DP_PSR_RFB_STORAGE_ERROR) {
-               DRM_DEBUG_KMS("PSR RFB storage error, exiting PSR\n");
+       if (val & (DP_PSR_RFB_STORAGE_ERROR | DP_PSR_LINK_CRC_ERROR)) {
+               if (val & DP_PSR_RFB_STORAGE_ERROR)
+                       DRM_DEBUG_KMS("PSR RFB storage error, disabling PSR\n");
+               if (val & DP_PSR_LINK_CRC_ERROR)
+                       DRM_DEBUG_KMS("PSR Link CRC error, disabling PSR\n");
                psr_disable(intel_dp);
        }
-       if (val & (DP_PSR_VSC_SDP_UNCORRECTABLE_ERROR | DP_PSR_LINK_CRC_ERROR))
+       if (val & DP_PSR_VSC_SDP_UNCORRECTABLE_ERROR)
                DRM_ERROR("PSR_ERROR_STATUS not handled %x\n", val);
        /* clear status register */
        drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_ERROR_STATUS, val);
 
-       /* TODO: handle other PSR/PSR2 errors */
+       /* TODO: handle PSR2 errors */
 exit:
        mutex_unlock(&psr->lock);
 }
-- 
2.17.0

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