drm/i915/psr: Only handle interruptions of the transcoder in use

It was enabling and checking PSR interruptions in every transcoder
while it should keep the interruptions on the non-used transcoders
masked.

While doing this it gives us trouble on Tiger Lake if we are
reading/writing to registers of disabled transcoders since from gen12
onwards the registers are relative to the transcoder. Instead of forcing
them ON to access those registers, just avoid the accesses as they are
not needed.

v2 (Lucas):
  - Explain why we can't keep accessing all transcoders
  - Remove TODO about extending the irq handling to multiple instances:
    when/if implementing multiple instances it's pretty clear by the
    singleton psr that it needs to be extended
  - Fix intel_psr_debug_set() calling psr_irq_control() with
    psr.transcoder not set yet (from Imre). Now we only set the debug
    register right away if psr is already enabled. Otherwise we just
    record the value to be set when enabling the source.
  - Do not depend on the value of TRANSCODER_A. Just be relative to it
    (from Imre)
  - handle psr error last so we don't schedule the work before handling
    the other flags

v3:
  - Adding a warning about setting reserverd bits on EDP_PSR_IMR

Cc: Imre Deak <imre.deak@intel.com>
Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190904213419.27547-2-jose.souza@intel.com

drivers/gpu/drm/i915/display/intel_psr.c

@@ -88,48 +88,20 @@ static bool intel_psr2_enabled(struct drm_i915_private *dev_priv,
 	}
 }
 
-static int edp_psr_shift(enum transcoder cpu_transcoder)
+static void psr_irq_control(struct drm_i915_private *dev_priv)
 {
-	switch (cpu_transcoder) {
-	case TRANSCODER_A:
-		return EDP_PSR_TRANSCODER_A_SHIFT;
-	case TRANSCODER_B:
-		return EDP_PSR_TRANSCODER_B_SHIFT;
-	case TRANSCODER_C:
-		return EDP_PSR_TRANSCODER_C_SHIFT;
-	default:
-		MISSING_CASE(cpu_transcoder);
-		/* fallthrough */
-	case TRANSCODER_EDP:
-		return EDP_PSR_TRANSCODER_EDP_SHIFT;
-	}
-}
-
-static void psr_irq_control(struct drm_i915_private *dev_priv, u32 debug)
-{
-	u32 debug_mask, mask;
-	enum transcoder cpu_transcoder;
-	u32 transcoders = BIT(TRANSCODER_EDP);
-
-	if (INTEL_GEN(dev_priv) >= 8)
-		transcoders |= BIT(TRANSCODER_A) |
-			       BIT(TRANSCODER_B) |
-			       BIT(TRANSCODER_C);
-
-	debug_mask = 0;
-	mask = 0;
-	for_each_cpu_transcoder_masked(dev_priv, cpu_transcoder, transcoders) {
-		int shift = edp_psr_shift(cpu_transcoder);
-
-		mask |= EDP_PSR_ERROR(shift);
-		debug_mask |= EDP_PSR_POST_EXIT(shift) |
-			      EDP_PSR_PRE_ENTRY(shift);
-	}
-
-	if (debug & I915_PSR_DEBUG_IRQ)
-		mask |= debug_mask;
-
-	I915_WRITE(EDP_PSR_IMR, ~mask);
+	enum transcoder trans = dev_priv->psr.transcoder;
+	u32 val, mask;
+
+	mask = EDP_PSR_ERROR(trans);
+	if (dev_priv->psr.debug & I915_PSR_DEBUG_IRQ)
+		mask |= EDP_PSR_POST_EXIT(trans) | EDP_PSR_PRE_ENTRY(trans);
+
+	/* Warning: it is masking/setting reserved bits too */
+	val = I915_READ(EDP_PSR_IMR);
+	val &= ~EDP_PSR_TRANS_MASK(trans);
+	val |= ~mask;
+	I915_WRITE(EDP_PSR_IMR, val);
 }
 
 static void psr_event_print(u32 val, bool psr2_enabled)
@@ -171,60 +143,48 @@ static void psr_event_print(u32 val, bool psr2_enabled)
 
 void intel_psr_irq_handler(struct drm_i915_private *dev_priv, u32 psr_iir)
 {
-	u32 transcoders = BIT(TRANSCODER_EDP);
-	enum transcoder cpu_transcoder;
+	enum transcoder cpu_transcoder = dev_priv->psr.transcoder;
 	ktime_t time_ns =  ktime_get();
-	u32 mask = 0;
-
-	if (INTEL_GEN(dev_priv) >= 8)
-		transcoders |= BIT(TRANSCODER_A) |
-			       BIT(TRANSCODER_B) |
-			       BIT(TRANSCODER_C);
-
-	for_each_cpu_transcoder_masked(dev_priv, cpu_transcoder, transcoders) {
-		int shift = edp_psr_shift(cpu_transcoder);
 
-		if (psr_iir & EDP_PSR_ERROR(shift)) {
-			DRM_WARN("[transcoder %s] PSR aux error\n",
-				 transcoder_name(cpu_transcoder));
+	if (psr_iir & EDP_PSR_PRE_ENTRY(cpu_transcoder)) {
+		dev_priv->psr.last_entry_attempt = time_ns;
+		DRM_DEBUG_KMS("[transcoder %s] PSR entry attempt in 2 vblanks\n",
+			      transcoder_name(cpu_transcoder));
+	}
 
-			dev_priv->psr.irq_aux_error = true;
+	if (psr_iir & EDP_PSR_POST_EXIT(cpu_transcoder)) {
+		dev_priv->psr.last_exit = time_ns;
+		DRM_DEBUG_KMS("[transcoder %s] PSR exit completed\n",
+			      transcoder_name(cpu_transcoder));
 
-			/*
-			 * If this interruption is not masked it will keep
-			 * interrupting so fast that it prevents the scheduled
-			 * work to run.
-			 * Also after a PSR error, we don't want to arm PSR
-			 * again so we don't care about unmask the interruption
-			 * or unset irq_aux_error.
-			 */
-			mask |= EDP_PSR_ERROR(shift);
-		}
+		if (INTEL_GEN(dev_priv) >= 9) {
+			u32 val = I915_READ(PSR_EVENT(cpu_transcoder));
+			bool psr2_enabled = dev_priv->psr.psr2_enabled;
 
-		if (psr_iir & EDP_PSR_PRE_ENTRY(shift)) {
-			dev_priv->psr.last_entry_attempt = time_ns;
-			DRM_DEBUG_KMS("[transcoder %s] PSR entry attempt in 2 vblanks\n",
-				      transcoder_name(cpu_transcoder));
+			I915_WRITE(PSR_EVENT(cpu_transcoder), val);
+			psr_event_print(val, psr2_enabled);
 		}
+	}
 
-		if (psr_iir & EDP_PSR_POST_EXIT(shift)) {
-			dev_priv->psr.last_exit = time_ns;
-			DRM_DEBUG_KMS("[transcoder %s] PSR exit completed\n",
-				      transcoder_name(cpu_transcoder));
+	if (psr_iir & EDP_PSR_ERROR(cpu_transcoder)) {
+		u32 val;
 
-			if (INTEL_GEN(dev_priv) >= 9) {
-				u32 val = I915_READ(PSR_EVENT(cpu_transcoder));
-				bool psr2_enabled = dev_priv->psr.psr2_enabled;
+		DRM_WARN("[transcoder %s] PSR aux error\n",
+			 transcoder_name(cpu_transcoder));
 
-				I915_WRITE(PSR_EVENT(cpu_transcoder), val);
-				psr_event_print(val, psr2_enabled);
-			}
-		}
-	}
+		dev_priv->psr.irq_aux_error = true;
 
-	if (mask) {
-		mask |= I915_READ(EDP_PSR_IMR);
-		I915_WRITE(EDP_PSR_IMR, mask);
+		/*
+		 * If this interruption is not masked it will keep
+		 * interrupting so fast that it prevents the scheduled
+		 * work to run.
+		 * Also after a PSR error, we don't want to arm PSR
+		 * again so we don't care about unmask the interruption
+		 * or unset irq_aux_error.
+		 */
+		val = I915_READ(EDP_PSR_IMR);
+		val |= EDP_PSR_ERROR(cpu_transcoder);
+		I915_WRITE(EDP_PSR_IMR, val);
 
 		schedule_work(&dev_priv->psr.work);
 	}
@@ -747,7 +707,7 @@ static void intel_psr_enable_source(struct intel_dp *intel_dp,
 
 	I915_WRITE(EDP_PSR_DEBUG(dev_priv->psr.transcoder), mask);
 
-	psr_irq_control(dev_priv, dev_priv->psr.debug);
+	psr_irq_control(dev_priv);
 }
 
 static void intel_psr_enable_locked(struct drm_i915_private *dev_priv,
@@ -772,7 +732,7 @@ static void intel_psr_enable_locked(struct drm_i915_private *dev_priv,
 	 * to avoid any rendering problems.
 	 */
 	val = I915_READ(EDP_PSR_IIR);
-	val &= EDP_PSR_ERROR(edp_psr_shift(dev_priv->psr.transcoder));
+	val &= EDP_PSR_ERROR(dev_priv->psr.transcoder);
 	if (val) {
 		dev_priv->psr.sink_not_reliable = true;
 		DRM_DEBUG_KMS("PSR interruption error set, not enabling PSR\n");
@@ -1120,7 +1080,13 @@ int intel_psr_debug_set(struct drm_i915_private *dev_priv, u64 val)
 
 	old_mode = dev_priv->psr.debug & I915_PSR_DEBUG_MODE_MASK;
 	dev_priv->psr.debug = val;
-	psr_irq_control(dev_priv, dev_priv->psr.debug);
+
+	/*
+	 * Do it right away if it's already enabled, otherwise it will be done
+	 * when enabling the source.
+	 */
+	if (dev_priv->psr.enabled)
+		psr_irq_control(dev_priv);
 
 	mutex_unlock(&dev_priv->psr.lock);
 

drivers/gpu/drm/i915/i915_reg.h

@@ -4225,13 +4225,12 @@ enum {
 /* Bspec claims those aren't shifted but stay at 0x64800 */
 #define EDP_PSR_IMR				_MMIO(0x64834)
 #define EDP_PSR_IIR				_MMIO(0x64838)
-#define   EDP_PSR_ERROR(shift)			(1 << ((shift) + 2))
-#define   EDP_PSR_POST_EXIT(shift)		(1 << ((shift) + 1))
-#define   EDP_PSR_PRE_ENTRY(shift)		(1 << (shift))
-#define   EDP_PSR_TRANSCODER_C_SHIFT		24
-#define   EDP_PSR_TRANSCODER_B_SHIFT		16
-#define   EDP_PSR_TRANSCODER_A_SHIFT		8
-#define   EDP_PSR_TRANSCODER_EDP_SHIFT		0
+#define   _EDP_PSR_TRANS_SHIFT(trans)		((trans) == TRANSCODER_EDP ? \
+						 0 : ((trans) - TRANSCODER_A + 1) * 8)
+#define   EDP_PSR_TRANS_MASK(trans)		(0x7 << _EDP_PSR_TRANS_SHIFT(trans))
+#define   EDP_PSR_ERROR(trans)			(0x4 << _EDP_PSR_TRANS_SHIFT(trans))
+#define   EDP_PSR_POST_EXIT(trans)		(0x2 << _EDP_PSR_TRANS_SHIFT(trans))
+#define   EDP_PSR_PRE_ENTRY(trans)		(0x1 << _EDP_PSR_TRANS_SHIFT(trans))
 
 #define _SRD_AUX_CTL_A				0x60810
 #define _SRD_AUX_CTL_EDP			0x6f810