drm: hdlcd: Revamp runtime power management

Because the HDLCD driver acts as a component master it can end
up enabling the runtime PM functionality before the encoders
are initialised. This can cause crashes if the component slave
never probes (missing module) or if the PM operations kick in
before the probe finishes.

Move the enabling of the runtime PM after the component master
has finished collecting the slave components and use the DRM
atomic helpers to suspend and resume the device.

Tested-by: Robin Murphy <Robin.Murphy@arm.com>
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>

1 files changed, 11 insertions, 12 deletions

diff --git a/drivers/gpu/drm/arm/hdlcd_crtc.c b/drivers/gpu/drm/arm/hdlcd_crtc.c
index fef1b04c2aab..d1e8d31e37ee 100644
--- a/drivers/gpu/drm/arm/hdlcd_crtc.c
+++ b/drivers/gpu/drm/arm/hdlcd_crtc.c
@@ -33,8 +33,17 @@
  *
  */
 
+static void hdlcd_crtc_cleanup(struct drm_crtc *crtc)
+{
+	struct hdlcd_drm_private *hdlcd = crtc_to_hdlcd_priv(crtc);
+
+	/* stop the controller on cleanup */
+	hdlcd_write(hdlcd, HDLCD_REG_COMMAND, 0);
+	drm_crtc_cleanup(crtc);
+}
+
 static const struct drm_crtc_funcs hdlcd_crtc_funcs = {
-	.destroy = drm_crtc_cleanup,
+	.destroy = hdlcd_crtc_cleanup,
 	.set_config = drm_atomic_helper_set_config,
 	.page_flip = drm_atomic_helper_page_flip,
 	.reset = drm_atomic_helper_crtc_reset,
@@ -155,8 +164,8 @@ static void hdlcd_crtc_disable(struct drm_crtc *crtc)
 	if (!crtc->primary->fb)
 		return;
 
-	clk_disable_unprepare(hdlcd->clk);
 	hdlcd_write(hdlcd, HDLCD_REG_COMMAND, 0);
+	clk_disable_unprepare(hdlcd->clk);
 	drm_crtc_vblank_off(crtc);
 }
 
@@ -294,16 +303,6 @@ static struct drm_plane *hdlcd_plane_init(struct drm_device *drm)
 	return plane;
 }
 
-void hdlcd_crtc_suspend(struct drm_crtc *crtc)
-{
-	hdlcd_crtc_disable(crtc);
-}
-
-void hdlcd_crtc_resume(struct drm_crtc *crtc)
-{
-	hdlcd_crtc_enable(crtc);
-}
-
 int hdlcd_setup_crtc(struct drm_device *drm)
 {
 	struct hdlcd_drm_private *hdlcd = drm->dev_private;