Re: [PATCH v3 7/7] drm/vc4: kms: Don't disable the muxing of an active CRTC

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Hi

Am 05.11.20 um 14:56 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>
---
  drivers/gpu/drm/vc4/vc4_drv.h |  1 +
  drivers/gpu/drm/vc4/vc4_kms.c | 82 ++++++++++++++++++++---------------
  2 files changed, 48 insertions(+), 35 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
index 014113823647..325b53ff11b3 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.h
+++ b/drivers/gpu/drm/vc4/vc4_drv.h
@@ -524,6 +524,7 @@ struct vc4_crtc_state {
  	struct drm_mm_node mm;
  	bool feed_txp;
  	bool txp_armed;
+	bool needs_muxing;

Maybe rather 'update_muxing'.

More generally, I'd separate fields that contain actual CRTC state, such assigned_channel, from those that only contain transitional state during update-commit, such as needs_muxing.

  	unsigned int assigned_channel;
struct {
diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
index 0a231ae500e5..7ef164afa9e2 100644
--- a/drivers/gpu/drm/vc4/vc4_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_kms.c
@@ -226,10 +226,7 @@ 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;
@@ -237,50 +234,59 @@ 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->needs_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
@@ -787,17 +793,23 @@ static int vc4_pv_muxing_atomic_check(struct drm_device *dev,
  		struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);
  		unsigned int matching_channels;
+ /* Nothing to do here, let's skip it */
+		if ((old_crtc_state->enable && new_crtc_state->enable) ||
+		    (!old_crtc_state->enable && !new_crtc_state->enable)) {

'if (old_crtc_state->enable == new_crtc_state->enable)' ?

+			new_vc4_crtc_state->needs_muxing = false;

Shouldn't this be cleared after duplicating the crtc state? No need to clear it then.

+			continue;
+		}
+
+		/* Muxing will need to be modified, mark it as such */
+		new_vc4_crtc_state->needs_muxing = true;
+
+		/* If we're disabling our CRTC, we put back our channel */
  		if (old_crtc_state->enable && !new_crtc_state->enable) {

You've already checked that enable is different, so you can leave out the test on old_crtc_state->enable

With my suggestions considered

Acked-by: Thomas Zimmermann <tzimmermann@xxxxxxx>


  			hvs_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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