Hi Jammy,

On 1/21/22 07:01, Jammy Huang wrote:

Hi Hans,

Yes, this is a weird part of our hardware.
Because it uses the rising edge of the sync to start counting, an additional calculation
is needed to get the exact value of the timings.

This problem was found when I was debugging the timing detection unstable problem.

OK, thank you for the confirmation.

I would like a v3 where basically the explanation you made in the cover letter
is copied to the code, probably as a comment block just before aspeed_video_get_resolution().

This is unusual enough that it should be documented well in the code.

Regards,

	Hans

Reards,

Jammy

On 2022/1/20 下午 08:31, Hans Verkuil wrote:

quoted

Hi Jammy,

I just want to double check this: I assume you have tested this with the
various polarity combinations?

I ask because I've never seen this before in any other hardware. The
sync and porch values reported by hardware are always independent from the
polarity, so that's why I am surprised to see this.

Same for the next patch (4/4).

Regards,

    Hans

On 12/22/21 09:21, Jammy Huang wrote:

quoted

Correct timing's fp/sync/bp value based on the information below.
It should be noticed that the calculation formula should be changed
per sync polarity.

The sequence of signal: sync - backporch - video data - frontporch

The following registers start counting from sync's rising edge:
1. VR090: frame edge's left and right
2. VR094: frame edge's top and bottom
3. VR09C: counting from sync's rising edge to falling edge

[Vertical timing]
             +--+     +-------------------+     +--+
             |  |     |    v i d e o      |     |  |
          +--+  +-----+                   +-----+  +---+

        vsync+--+
    frame_top+--------+
frame_bottom+----------------------------+

                   +-------------------+
                   |    v i d e o      |
       +--+  +-----+                   +-----+  +---+
          |  |                               |  |
          +--+                               +--+
        vsync+-------------------------------+
    frame_top+-----+
frame_bottom+-------------------------+

[Horizontal timing]
             +--+     +-------------------+     +--+
             |  |     |    v i d e o      |     |  |
          +--+  +-----+                   +-----+  +---+

        hsync+--+
   frame_left+--------+
  frame_right+----------------------------+

                   +-------------------+
                   |    v i d e o      |
       +--+  +-----+                   +-----+  +---+
          |  |                               |  |
          +--+                               +--+
        hsync+-------------------------------+
   frame_left+-----+
  frame_right+-------------------------+

Signed-off-by: Jammy Huang <redacted>
---
  v2:
   - Code refined per Joel's suggestion
   - Update commit message to have name matching variable
---
  drivers/media/platform/aspeed-video.c | 30 ++++++++++++++++++++-------
  1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/drivers/media/platform/aspeed-video.c b/drivers/media/platform/aspeed-video.c
index c241038ee27c..7c50567f5ab0 100644
--- a/drivers/media/platform/aspeed-video.c
+++ b/drivers/media/platform/aspeed-video.c

@@ -936,7 +936,7 @@ static void aspeed_video_get_resolution(struct aspeed_video *video)

      u32 src_lr_edge;
      u32 src_tb_edge;
      u32 sync;
-    u32 htotal;
+    u32 htotal, vtotal, vsync, hsync;
      struct v4l2_bt_timings *det = &video->detected_timings;
        det->width = MIN_WIDTH;

@@ -983,21 +983,35 @@ static void aspeed_video_get_resolution(struct aspeed_video *video)

          mds = aspeed_video_read(video, VE_MODE_DETECT_STATUS);
          sync = aspeed_video_read(video, VE_SYNC_STATUS);
          htotal = aspeed_video_read(video, VE_H_TOTAL_PIXELS);
+        vtotal = FIELD_GET(VE_MODE_DETECT_V_LINES, mds);
+        vsync = FIELD_GET(VE_SYNC_STATUS_VSYNC, sync);
+        hsync = FIELD_GET(VE_SYNC_STATUS_HSYNC, sync);
            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);
-        det->vfrontporch = video->frame_top;
-        det->vbackporch = FIELD_GET(VE_MODE_DETECT_V_LINES, mds) -
-            video->frame_bottom;
-        det->vsync = FIELD_GET(VE_SYNC_STATUS_VSYNC, sync);
+        if (det->polarities & V4L2_DV_VSYNC_POS_POL) {
+            det->vbackporch = video->frame_top - vsync;
+            det->vfrontporch = vtotal - video->frame_bottom;
+            det->vsync = vsync;
+        } else {
+            det->vbackporch = video->frame_top;
+            det->vfrontporch = vsync - video->frame_bottom;
+            det->vsync = vtotal - vsync;
+        }
          if (video->frame_top > video->frame_bottom)
              continue;
            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);
-        det->hfrontporch = video->frame_left;
-        det->hbackporch = htotal - video->frame_right;
-        det->hsync = FIELD_GET(VE_SYNC_STATUS_HSYNC, sync);
+        if (det->polarities & V4L2_DV_HSYNC_POS_POL) {
+            det->hbackporch = video->frame_left - hsync;
+            det->hfrontporch = htotal - video->frame_right;
+            det->hsync = hsync;
+        } else {
+            det->hbackporch = video->frame_left;
+            det->hfrontporch = hsync - video->frame_right;
+            det->hsync = htotal - hsync;
+        }
          if (video->frame_left > video->frame_right)
              continue;
  

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