drm/vc4: hvs: Correct logic on stopping an HVS channel

[ Upstream commit 7ab6512 ]

When factoring out __vc4_hvs_stop_channel, the logic got inverted from
	if (condition)
	  // stop channel
to
	if (condition)
	  goto out
	//stop channel
	out:
and also changed the exact register writes used to stop the channel.

Correct the logic so that the channel is actually stopped, and revert
to the original register writes.

Fixes: 6d01a10 ("drm/vc4: crtc: Move HVS init and close to a function")
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240621152055.4180873-32-dave.stevenson@raspberrypi.com
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/gpu/drm/vc4/vc4_hvs.c

@@ -418,13 +418,11 @@ void vc4_hvs_stop_channel(struct vc4_hvs *hvs, unsigned int chan)
 	if (!drm_dev_enter(drm, &idx))
 		return;
 
-	if (HVS_READ(SCALER_DISPCTRLX(chan)) & SCALER_DISPCTRLX_ENABLE)
+	if (!(HVS_READ(SCALER_DISPCTRLX(chan)) & SCALER_DISPCTRLX_ENABLE))
 		goto out;
 
-	HVS_WRITE(SCALER_DISPCTRLX(chan),
-		  HVS_READ(SCALER_DISPCTRLX(chan)) | SCALER_DISPCTRLX_RESET);
-	HVS_WRITE(SCALER_DISPCTRLX(chan),
-		  HVS_READ(SCALER_DISPCTRLX(chan)) & ~SCALER_DISPCTRLX_ENABLE);
+	HVS_WRITE(SCALER_DISPCTRLX(chan), SCALER_DISPCTRLX_RESET);
+	HVS_WRITE(SCALER_DISPCTRLX(chan), 0);
 
 	/* Once we leave, the scaler should be disabled and its fifo empty. */
 	WARN_ON_ONCE(HVS_READ(SCALER_DISPCTRLX(chan)) & SCALER_DISPCTRLX_RESET);