drm/vc4: hvs: Make the stop_channel function public

During the transition from the firmware to the KMS driver, we need to pay
particular attention to how we deal with the pixelvalves that have already
been enabled, otherwise either timeouts or stuck pixels can occur. We'll
thus need to call the function to stop an HVS channel at boot.
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Tested-by: Chanwoo Choi <cw00.choi@samsung.com>
Tested-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/a9d5f0891c3bc1deb6b16d56ca6994ed912ec7c7.1599120059.git-series.maxime@cerno.tech

drivers/gpu/drm/vc4/vc4_drv.h

@@ -907,6 +907,7 @@ void vc4_irq_reset(struct drm_device *dev);
 
 /* vc4_hvs.c */
 extern struct platform_driver vc4_hvs_driver;
+void vc4_hvs_stop_channel(struct drm_device *dev, unsigned int output);
 int vc4_hvs_atomic_check(struct drm_crtc *crtc, struct drm_crtc_state *state);
 void vc4_hvs_atomic_enable(struct drm_crtc *crtc, struct drm_crtc_state *old_state);
 void vc4_hvs_atomic_disable(struct drm_crtc *crtc, struct drm_crtc_state *old_state);

drivers/gpu/drm/vc4/vc4_hvs.c

@@ -248,7 +248,7 @@ static int vc4_hvs_init_channel(struct vc4_dev *vc4, struct drm_crtc *crtc,
 	return 0;
 }
 
-static void vc4_hvs_stop_channel(struct drm_device *dev, unsigned int chan)
+void vc4_hvs_stop_channel(struct drm_device *dev, unsigned int chan)
 {
 	struct vc4_dev *vc4 = to_vc4_dev(dev);