drm/amd/display: Skip 2 frames when first reading CRC

Skipping the first frame will prevent uncoooked values most of the time.
However, in some unlikely cases, the second frame will be uncooked as
well.

Signed-off-by: Leo (Sunpeng) Li <sunpeng.li@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
index ed939600cdbe486c17b29093a8465804dda0f4a1..aa7df57755459e6ccfb0aaa3c4a2e720bba76233 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
@@ -198,7 +198,7 @@ struct dm_crtc_state {
        struct drm_crtc_state base;
        struct dc_stream_state *stream;
 
-       bool crc_first_skipped;
+       int crc_skip_count;
        bool crc_enabled;
 };
 

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crc.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crc.c
index 55aa379cfcbef386c3800a7b4288b5765f02b57b..52f2c01349e38214c9bad2e3e639a69717828d0a 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crc.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crc.c
@@ -84,8 +84,8 @@ int amdgpu_dm_crtc_set_crc_source(struct drm_crtc *crtc, const char *src_name,
        }
 
        *values_cnt = 3;
-       /* Reset crc_skipped flag on dm state */
-       crtc_state->crc_first_skipped = false;
+       /* Reset crc_skipped on dm state */
+       crtc_state->crc_skip_count = 0;
        return 0;
 }
 
@@ -109,11 +109,11 @@ void amdgpu_dm_crtc_handle_crc_irq(struct drm_crtc *crtc)
        /*
         * Since flipping and crc enablement happen asynchronously, we - more
         * often than not - will be returning an 'uncooked' crc on first frame.
-        * Probably because hw isn't ready yet. Simply skip the first crc
-        * value.
+        * Probably because hw isn't ready yet. For added security, skip the
+        * first two CRC values.
         */
-       if (!crtc_state->crc_first_skipped) {
-               crtc_state->crc_first_skipped = true;
+       if (crtc_state->crc_skip_count < 2) {
+               crtc_state->crc_skip_count += 1;
                return;
        }