Re: [PATCH v4 2/2] drm/vc4: kms: Don't disable the muxing of an active CRTC

Thomas Zimmermann <tzimmermann@xxxxxxx> · Mon, 23 Nov 2020 08:50:49 +0100

Am 20.11.20 um 15:42 schrieb Maxime Ripard:
The current HVS muxing code will consider the CRTCs in a given state to
setup their muxing in the HVS, and disable the other CRTCs muxes.

However, it's valid to only update a single CRTC with a state, and in this
situation we would mux out a CRTC that was enabled but left untouched by
the new state.

Fix this by setting a flag on the CRTC state when the muxing has been
changed, and only change the muxing configuration when that flag is there.

Fixes: 87ebcd42fb7b ("drm/vc4: crtc: Assign output to channel automatically")
Reviewed-by: Hoegeun Kwon <hoegeun.kwon@xxxxxxxxxxx>
Tested-by: Hoegeun Kwon <hoegeun.kwon@xxxxxxxxxxx>
Signed-off-by: Maxime Ripard <maxime@xxxxxxxxxx>

Reviewed-by: Thomas Zimmermann <tzimmermann@xxxxxxx>

---
  drivers/gpu/drm/vc4/vc4_drv.h |  3 ++
  drivers/gpu/drm/vc4/vc4_kms.c | 81 +++++++++++++++++++----------------
  2 files changed, 48 insertions(+), 36 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
index fcfeef0949af..c5f2944d5bc6 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.h
+++ b/drivers/gpu/drm/vc4/vc4_drv.h
@@ -532,6 +532,9 @@ struct vc4_crtc_state {
  		unsigned int top;
  		unsigned int bottom;
  	} margins;
+
+	/* Transitional state below, only valid during atomic commits */
+	bool update_muxing;
  };
  
  #define VC4_HVS_CHANNEL_DISABLED ((unsigned int)-1)
diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
index 0bbd7b554275..ba310c0ab5f6 100644
--- a/drivers/gpu/drm/vc4/vc4_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_kms.c
@@ -239,10 +239,7 @@ static void vc5_hvs_pv_muxing_commit(struct vc4_dev *vc4,
  {
  	struct drm_crtc_state *crtc_state;
  	struct drm_crtc *crtc;
-	unsigned char dsp2_mux = 0;
-	unsigned char dsp3_mux = 3;
-	unsigned char dsp4_mux = 3;
-	unsigned char dsp5_mux = 3;
+	unsigned char mux;
  	unsigned int i;
  	u32 reg;
  
@@ -250,50 +247,59 @@ static void vc5_hvs_pv_muxing_commit(struct vc4_dev *vc4,
  		struct vc4_crtc_state *vc4_state = to_vc4_crtc_state(crtc_state);
  		struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);
  
-		if (!crtc_state->active)
+		if (!vc4_state->update_muxing)
  			continue;
  
  		switch (vc4_crtc->data->hvs_output) {
  		case 2:
-			dsp2_mux = (vc4_state->assigned_channel == 2) ? 0 : 1;
+			mux = (vc4_state->assigned_channel == 2) ? 0 : 1;
+			reg = HVS_READ(SCALER_DISPECTRL);
+			HVS_WRITE(SCALER_DISPECTRL,
+				  (reg & ~SCALER_DISPECTRL_DSP2_MUX_MASK) |
+				  VC4_SET_FIELD(mux, SCALER_DISPECTRL_DSP2_MUX));
  			break;
  
  		case 3:
-			dsp3_mux = vc4_state->assigned_channel;
+			if (vc4_state->assigned_channel == VC4_HVS_CHANNEL_DISABLED)
+				mux = 3;
+			else
+				mux = vc4_state->assigned_channel;
+
+			reg = HVS_READ(SCALER_DISPCTRL);
+			HVS_WRITE(SCALER_DISPCTRL,
+				  (reg & ~SCALER_DISPCTRL_DSP3_MUX_MASK) |
+				  VC4_SET_FIELD(mux, SCALER_DISPCTRL_DSP3_MUX));
  			break;
  
  		case 4:
-			dsp4_mux = vc4_state->assigned_channel;
+			if (vc4_state->assigned_channel == VC4_HVS_CHANNEL_DISABLED)
+				mux = 3;
+			else
+				mux = vc4_state->assigned_channel;
+
+			reg = HVS_READ(SCALER_DISPEOLN);
+			HVS_WRITE(SCALER_DISPEOLN,
+				  (reg & ~SCALER_DISPEOLN_DSP4_MUX_MASK) |
+				  VC4_SET_FIELD(mux, SCALER_DISPEOLN_DSP4_MUX));
+
  			break;
  
  		case 5:
-			dsp5_mux = vc4_state->assigned_channel;
+			if (vc4_state->assigned_channel == VC4_HVS_CHANNEL_DISABLED)
+				mux = 3;
+			else
+				mux = vc4_state->assigned_channel;
+
+			reg = HVS_READ(SCALER_DISPDITHER);
+			HVS_WRITE(SCALER_DISPDITHER,
+				  (reg & ~SCALER_DISPDITHER_DSP5_MUX_MASK) |
+				  VC4_SET_FIELD(mux, SCALER_DISPDITHER_DSP5_MUX));
  			break;
  
  		default:
  			break;
  		}
  	}
-
-	reg = HVS_READ(SCALER_DISPECTRL);
-	HVS_WRITE(SCALER_DISPECTRL,
-		  (reg & ~SCALER_DISPECTRL_DSP2_MUX_MASK) |
-		  VC4_SET_FIELD(dsp2_mux, SCALER_DISPECTRL_DSP2_MUX));
-
-	reg = HVS_READ(SCALER_DISPCTRL);
-	HVS_WRITE(SCALER_DISPCTRL,
-		  (reg & ~SCALER_DISPCTRL_DSP3_MUX_MASK) |
-		  VC4_SET_FIELD(dsp3_mux, SCALER_DISPCTRL_DSP3_MUX));
-
-	reg = HVS_READ(SCALER_DISPEOLN);
-	HVS_WRITE(SCALER_DISPEOLN,
-		  (reg & ~SCALER_DISPEOLN_DSP4_MUX_MASK) |
-		  VC4_SET_FIELD(dsp4_mux, SCALER_DISPEOLN_DSP4_MUX));
-
-	reg = HVS_READ(SCALER_DISPDITHER);
-	HVS_WRITE(SCALER_DISPDITHER,
-		  (reg & ~SCALER_DISPDITHER_DSP5_MUX_MASK) |
-		  VC4_SET_FIELD(dsp5_mux, SCALER_DISPDITHER_DSP5_MUX));
  }
  
  static void
@@ -789,17 +795,20 @@ static int vc4_pv_muxing_atomic_check(struct drm_device *dev,
  		struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);
  		unsigned int matching_channels;
  
-		if (old_crtc_state->enable && !new_crtc_state->enable) {
+		/* Nothing to do here, let's skip it */
+		if (old_crtc_state->enable == new_crtc_state->enable)
+			continue;
+
+		/* Muxing will need to be modified, mark it as such */
+		new_vc4_crtc_state->update_muxing = true;
+
+		/* If we're disabling our CRTC, we put back our channel */
+		if (!new_crtc_state->enable) {
  			hvs_new_state->unassigned_channels |= BIT(old_vc4_crtc_state->assigned_channel);
  			new_vc4_crtc_state->assigned_channel = VC4_HVS_CHANNEL_DISABLED;
+			continue;
  		}
  
-		if (!new_crtc_state->enable)
-			continue;
-
-		if (new_vc4_crtc_state->assigned_channel != VC4_HVS_CHANNEL_DISABLED)
-			continue;
-
  		/*
  		 * The problem we have to solve here is that we have
  		 * up to 7 encoders, connected to up to 6 CRTCs.


--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer
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