drm/vc4: hvs: Set AXI panic modes

The HVS can change AXI request mode based on how full the COB
FIFOs are.
Until now the vc4 driver has been relying on the firmware to
have set these to sensible values.

With HVS channel 2 now being used for live video, change the
panic mode for all channels to be explicitly set by the driver,
and the same for all channels.

Fixes: c54619b0 ("drm/vc4: Add support for the BCM2711 HVS5")
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Link: https://lore.kernel.org/r/20221207-rpi-hvs-crtc-misc-v1-2-1f8e0770798b@cerno.techSigned-off-by: Maxime Ripard <maxime@cerno.tech>

drivers/gpu/drm/vc4/vc4_hvs.c

@@ -913,6 +913,17 @@ static int vc4_hvs_bind(struct device *dev, struct device *master, void *data)
 		      SCALER_DISPCTRL_DSPEISLUR(2) |
 		      SCALER_DISPCTRL_SCLEIRQ);
 
+	/* Set AXI panic mode.
+	 * VC4 panics when < 2 lines in FIFO.
+	 * VC5 panics when less than 1 line in the FIFO.
+	 */
+	dispctrl &= ~(SCALER_DISPCTRL_PANIC0_MASK |
+		      SCALER_DISPCTRL_PANIC1_MASK |
+		      SCALER_DISPCTRL_PANIC2_MASK);
+	dispctrl |= VC4_SET_FIELD(2, SCALER_DISPCTRL_PANIC0);
+	dispctrl |= VC4_SET_FIELD(2, SCALER_DISPCTRL_PANIC1);
+	dispctrl |= VC4_SET_FIELD(2, SCALER_DISPCTRL_PANIC2);
+
 	HVS_WRITE(SCALER_DISPCTRL, dispctrl);
 
 	/* Recompute Composite Output Buffer (COB) allocations for the displays

drivers/gpu/drm/vc4/vc4_regs.h

@@ -220,6 +220,12 @@
 #define SCALER_DISPCTRL                         0x00000000
 /* Global register for clock gating the HVS */
 # define SCALER_DISPCTRL_ENABLE			BIT(31)
+# define SCALER_DISPCTRL_PANIC0_MASK		VC4_MASK(25, 24)
+# define SCALER_DISPCTRL_PANIC0_SHIFT		24
+# define SCALER_DISPCTRL_PANIC1_MASK		VC4_MASK(27, 26)
+# define SCALER_DISPCTRL_PANIC1_SHIFT		26
+# define SCALER_DISPCTRL_PANIC2_MASK		VC4_MASK(29, 28)
+# define SCALER_DISPCTRL_PANIC2_SHIFT		28
 # define SCALER_DISPCTRL_DSP3_MUX_MASK		VC4_MASK(19, 18)
 # define SCALER_DISPCTRL_DSP3_MUX_SHIFT		18