drm/vc4: Set up SCALER_DISPCTRL at boot.

We want the HVS on, obviously, and we also want DSP3 (PV1's source) to
be muxed from HVS channel 2 like we expect in vc4_crtc.c.  The
firmware wasn't setting the DSP3 mux up when both the LCD and HDMI
were disabled.
Signed-off-by: Eric Anholt <eric@anholt.net>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161214194621.16499-5-eric@anholt.net

drivers/gpu/drm/vc4/vc4_hvs.c

@@ -170,6 +170,7 @@ static int vc4_hvs_bind(struct device *dev, struct device *master, void *data)
 	struct vc4_dev *vc4 = drm->dev_private;
 	struct vc4_hvs *hvs = NULL;
 	int ret;
+	u32 dispctrl;
 
 	hvs = devm_kzalloc(&pdev->dev, sizeof(*hvs), GFP_KERNEL);
 	if (!hvs)
@@ -211,6 +212,19 @@ static int vc4_hvs_bind(struct device *dev, struct device *master, void *data)
 		return ret;
 
 	vc4->hvs = hvs;
+
+	dispctrl = HVS_READ(SCALER_DISPCTRL);
+
+	dispctrl |= SCALER_DISPCTRL_ENABLE;
+
+	/* Set DSP3 (PV1) to use HVS channel 2, which would otherwise
+	 * be unused.
+	 */
+	dispctrl &= ~SCALER_DISPCTRL_DSP3_MUX_MASK;
+	dispctrl |= VC4_SET_FIELD(2, SCALER_DISPCTRL_DSP3_MUX);
+
+	HVS_WRITE(SCALER_DISPCTRL, dispctrl);
+
 	return 0;
 }
 

drivers/gpu/drm/vc4/vc4_regs.h

@@ -244,6 +244,9 @@
 # define SCALER_DISPCTRL_ENABLE			BIT(31)
 # define SCALER_DISPCTRL_DSP2EISLUR		BIT(15)
 # define SCALER_DISPCTRL_DSP1EISLUR		BIT(14)
+# define SCALER_DISPCTRL_DSP3_MUX_MASK		VC4_MASK(19, 18)
+# define SCALER_DISPCTRL_DSP3_MUX_SHIFT		18
+
 /* Enables Display 0 short line and underrun contribution to
  * SCALER_DISPSTAT_IRQDISP0.  Note that short frame contributions are
  * always enabled.