drm/tilcdc: Restore old dpms state in pm_resume()

Restore old dpms state in pm_resume(). The dpms is turned off in
pm_suspend() and it should be restored to its original state in
pm_resume(). Without this patch the display is left blanked after a
suspend/resume cycle.

Fixes commit 614b3cfeb8d2 ("drm/tilcdc: disable the lcd controller/dma
engine when suspend invoked")

Signed-off-by: Jyri Sarha <jsarha@ti.com>

3 files changed, 12 insertions, 0 deletions

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
index 107c8bd04f6d..1601428c9b8e 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
@@ -246,6 +246,13 @@ void tilcdc_crtc_dpms(struct drm_crtc *crtc, int mode)
         }
 }
 
+int tilcdc_crtc_current_dpms_state(struct drm_crtc *crtc)
+{
+        struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
+
+        return tilcdc_crtc->dpms;
+}
+
 static bool tilcdc_crtc_mode_fixup(struct drm_crtc *crtc,
                 const struct drm_display_mode *mode,
                 struct drm_display_mode *adjusted_mode)
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_drv.c b/drivers/gpu/drm/tilcdc/tilcdc_drv.c
index d27809372d54..ed68324504f6 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_drv.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.c
@@ -597,6 +597,7 @@ static int tilcdc_pm_suspend(struct device *dev)
         }
 
         /* Disable the LCDC controller, to avoid locking up the PRCM */
+        priv->saved_dpms_state = tilcdc_crtc_current_dpms_state(priv->crtc);
         tilcdc_crtc_dpms(priv->crtc, DRM_MODE_DPMS_OFF);
 
         /* Save register state: */
@@ -627,6 +628,8 @@ static int tilcdc_pm_resume(struct device *dev)
                                              priv->saved_register[n++]);
         }
 
+        tilcdc_crtc_dpms(priv->crtc, priv->saved_dpms_state);
+
         drm_kms_helper_poll_enable(ddev);
 
         return 0;
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_drv.h b/drivers/gpu/drm/tilcdc/tilcdc_drv.h
index c1de18bae415..3b52ce8ab69c 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_drv.h
+++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.h
@@ -67,6 +67,7 @@ struct tilcdc_drm_private {
 
         /* register contents saved across suspend/resume: */
         u32 *saved_register;
+        int saved_dpms_state;
         bool ctx_valid;
 
 #ifdef CONFIG_CPU_FREQ
@@ -172,5 +173,6 @@ void tilcdc_crtc_set_simulate_vesa_sync(struct drm_crtc *crtc,
 int tilcdc_crtc_mode_valid(struct drm_crtc *crtc, struct drm_display_mode *mode);
 int tilcdc_crtc_max_width(struct drm_crtc *crtc);
 void tilcdc_crtc_dpms(struct drm_crtc *crtc, int mode);
+int tilcdc_crtc_current_dpms_state(struct drm_crtc *crtc);
 
 #endif /* __TILCDC_DRV_H__ */