drm/vc4: hdmi: Reset HDMI MISC_CONTROL register

The HDMI block can repeat pixels for double clocked modes,
and the firmware is now configuring the block to do this as
the PV is doing it incorrectly when at 2pixels/clock.
If the kernel doesn't reset it then we end up with strange
modes.

Reset MISC_CONTROL.

Fixes: 83239891 ("drm/vc4: hdmi: Support the BCM2711 HDMI controllers")
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Link: https://lore.kernel.org/r/20220613144800.326124-22-maxime@cerno.techSigned-off-by: Maxime Ripard <maxime@cerno.tech>

drivers/gpu/drm/vc4/vc4_hdmi.c

@@ -79,6 +79,9 @@
 #define VC5_HDMI_VERTB_VSPO_SHIFT		16
 #define VC5_HDMI_VERTB_VSPO_MASK		VC4_MASK(29, 16)
 
+#define VC5_HDMI_MISC_CONTROL_PIXEL_REP_SHIFT	0
+#define VC5_HDMI_MISC_CONTROL_PIXEL_REP_MASK	VC4_MASK(3, 0)
+
 #define VC5_HDMI_SCRAMBLER_CTL_ENABLE		BIT(0)
 
 #define VC5_HDMI_DEEP_COLOR_CONFIG_1_INIT_PACK_PHASE_SHIFT	8
@@ -1117,6 +1120,11 @@ static void vc5_hdmi_set_timings(struct vc4_hdmi *vc4_hdmi,
 	reg |= gcp_en ? VC5_HDMI_GCP_CONFIG_GCP_ENABLE : 0;
 	HDMI_WRITE(HDMI_GCP_CONFIG, reg);
 
+	reg = HDMI_READ(HDMI_MISC_CONTROL);
+	reg &= ~VC5_HDMI_MISC_CONTROL_PIXEL_REP_MASK;
+	reg |= VC4_SET_FIELD(0, VC5_HDMI_MISC_CONTROL_PIXEL_REP);
+	HDMI_WRITE(HDMI_MISC_CONTROL, reg);
+
 	HDMI_WRITE(HDMI_CLOCK_STOP, 0);
 
 	spin_unlock_irqrestore(&vc4_hdmi->hw_lock, flags);

drivers/gpu/drm/vc4/vc4_hdmi_regs.h

@@ -127,6 +127,7 @@ enum vc4_hdmi_field {
 	HDMI_VERTB0,
 	HDMI_VERTB1,
 	HDMI_VID_CTL,
+	HDMI_MISC_CONTROL,
 };
 
 struct vc4_hdmi_register {
@@ -237,6 +238,7 @@ static const struct vc4_hdmi_register __maybe_unused vc5_hdmi_hdmi0_fields[] = {
 	VC4_HDMI_REG(HDMI_VERTB0, 0x0f0),
 	VC4_HDMI_REG(HDMI_VERTA1, 0x0f4),
 	VC4_HDMI_REG(HDMI_VERTB1, 0x0f8),
+	VC4_HDMI_REG(HDMI_MISC_CONTROL, 0x100),
 	VC4_HDMI_REG(HDMI_MAI_CHANNEL_MAP, 0x09c),
 	VC4_HDMI_REG(HDMI_MAI_CONFIG, 0x0a0),
 	VC4_HDMI_REG(HDMI_DEEP_COLOR_CONFIG_1, 0x170),
@@ -319,6 +321,7 @@ static const struct vc4_hdmi_register __maybe_unused vc5_hdmi_hdmi1_fields[] = {
 	VC4_HDMI_REG(HDMI_VERTB0, 0x0f0),
 	VC4_HDMI_REG(HDMI_VERTA1, 0x0f4),
 	VC4_HDMI_REG(HDMI_VERTB1, 0x0f8),
+	VC4_HDMI_REG(HDMI_MISC_CONTROL, 0x100),
 	VC4_HDMI_REG(HDMI_MAI_CHANNEL_MAP, 0x09c),
 	VC4_HDMI_REG(HDMI_MAI_CONFIG, 0x0a0),
 	VC4_HDMI_REG(HDMI_DEEP_COLOR_CONFIG_1, 0x170),