[PATCH v2 4/4] media: aspeed: Fix timing polarity incorrect

Jammy Huang
2021-12-22T08:22:19Z

This is a workaround for sync polarity unstable.
Sync value get by VR09C counts from sync's rising edge, which means
sync's polarity is negative if sync value is bigger than total/2.

Signed-off-by: Jammy Huang <jammy_huang@aspeedtech.com>
---
v2:
- Use 'total/2' rather than 'total<<1'
- Update comment
---
drivers/media/platform/aspeed-video.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)

diff --git a/drivers/media/platform/aspeed-video.c b/drivers/media/platform/aspeed-video.c
index 7c50567f5ab0..c3e3343d91e1 100644
--- a/drivers/media/platform/aspeed-video.c
+++ b/drivers/media/platform/aspeed-video.c
@@ -989,6 +989,16 @@ static void aspeed_video_get_resolution(struct aspeed_video *video)

video->frame_bottom = FIELD_GET(VE_SRC_TB_EDGE_DET_BOT, src_tb_edge);
video->frame_top = FIELD_GET(VE_SRC_TB_EDGE_DET_TOP, src_tb_edge);
+
+ /*
+ * This is a workaround for polarity detection when the sync
+ * value is larger than half.
+ */
+ if (vsync > (vtotal / 2))
+ det->polarities &= ~V4L2_DV_VSYNC_POS_POL;
+ else
+ det->polarities |= V4L2_DV_VSYNC_POS_POL;
+
if (det->polarities & V4L2_DV_VSYNC_POS_POL) {
det->vbackporch = video->frame_top - vsync;
det->vfrontporch = vtotal - video->frame_bottom;
@@ -1003,6 +1013,16 @@ static void aspeed_video_get_resolution(struct aspeed_video *video)

video->frame_right = FIELD_GET(VE_SRC_LR_EDGE_DET_RT, src_lr_edge);
video->frame_left = FIELD_GET(VE_SRC_LR_EDGE_DET_LEFT, src_lr_edge);
+
+ /*
+ * This is a workaround for polarity detection when the sync
+ * value is larger than half.
+ */
+ if (hsync > (htotal / 2))
+ det->polarities &= ~V4L2_DV_HSYNC_POS_POL;
+ else
+ det->polarities |= V4L2_DV_HSYNC_POS_POL;
+
if (det->polarities & V4L2_DV_HSYNC_POS_POL) {
det->hbackporch = video->frame_left - hsync;
det->hfrontporch = htotal - video->frame_right;
--
2.25.1