[PATCH v2 7/7] drm/mediatek: Fix mtk_atomic_complete for runtime_pm

Bibby Hsieh
2016-08-04T02:59:57Z

To properly implement atomic w/ runtime pm, we move
drm_atomic_helper_commit_modeset_enables() above
drm_atomic_helper_commit_planes() to ensure CRTCs are enabled before
modifying plane registers, and set active_only to true to filter out
plane update notifications when the CRTC is disabled.

According to the document from linux kernel:
Set the active_only parameters to true in order not to receive plane
update notifications related to a disabled CRTC. This avoids the need
to manually ignore plane updates in driver code when the driver and/or
hardware can't or just don't need to deal with updates on disabled
CRTCs, for example when supporting runtime PM.

Signed-off-by: Bibby Hsieh <bibby.hsieh@mediatek.com>
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
---
drivers/gpu/drm/mediatek/mtk_drm_drv.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
index b1223d5..507392a 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
@@ -61,10 +61,25 @@ static void mtk_atomic_complete(struct mtk_drm_private *private,

mtk_atomic_wait_for_fences(state);

+ /*
+ * Mediatek drm supports runtime PM, so plane registers cannot be
+ * written when their crtc is disabled.
+ *
+ * The comment for drm_atomic_helper_commit states:
+ * For drivers supporting runtime PM the recommended sequence is
+ *
+ * drm_atomic_helper_commit_modeset_disables(dev, state);
+ * drm_atomic_helper_commit_modeset_enables(dev, state);
+ * drm_atomic_helper_commit_planes(dev, state, true);
+ *
+ * See the kerneldoc entries for these three functions for more details.
+ */
drm_atomic_helper_commit_modeset_disables(drm, state);
- drm_atomic_helper_commit_planes(drm, state, false);
drm_atomic_helper_commit_modeset_enables(drm, state);
+ drm_atomic_helper_commit_planes(drm, state, true);
+
drm_atomic_helper_wait_for_vblanks(drm, state);
+
drm_atomic_helper_cleanup_planes(drm, state);
drm_atomic_state_free(state);
}
--
1.7.9.5