media: aspeed: add a workaround to fix a silicon bug

AST2500 silicon revision A1 and A2 have a silicon bug which causes
extremly long capturing time on specific resolutions (1680 width).
To fix the bug, this commit adjusts the capturing window register
setting to 1728 if detected width is 1680. The compression window
register setting will be kept as the original width so output
result will be the same.

Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
Reviewed-by: Eddie James <eajames@linux.ibm.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

diff --git a/drivers/media/platform/aspeed-video.c b/drivers/media/platform/aspeed-video.c
index ba093096a5a7878d87fcafbc8bb6f32fde5174cb..f899ac3b4a6139b0337751cfca4cdff097b04364 100644 (file)
--- a/drivers/media/platform/aspeed-video.c
+++ b/drivers/media/platform/aspeed-video.c
@@ -824,8 +824,29 @@ static void aspeed_video_set_resolution(struct aspeed_video *video)
        struct v4l2_bt_timings *act = &video->active_timings;
        unsigned int size = act->width * act->height;
 
+       /* Set capture/compression frame sizes */
        aspeed_video_calc_compressed_size(video, size);
 
+       if (video->active_timings.width == 1680) {
+               /*
+                * This is a workaround to fix a silicon bug on A1 and A2
+                * revisions. Since it doesn't break capturing operation of
+                * other revisions, use it for all revisions without checking
+                * the revision ID. It picked 1728 which is a very next
+                * 64-pixels aligned value to 1680 to minimize memory bandwidth
+                * and to get better access speed from video engine.
+                */
+               aspeed_video_write(video, VE_CAP_WINDOW,
+                                  1728 << 16 | act->height);
+               size += (1728 - 1680) * video->active_timings.height;
+       } else {
+               aspeed_video_write(video, VE_CAP_WINDOW,
+                                  act->width << 16 | act->height);
+       }
+       aspeed_video_write(video, VE_COMP_WINDOW,
+                          act->width << 16 | act->height);
+       aspeed_video_write(video, VE_SRC_SCANLINE_OFFSET, act->width * 4);
+
        /* Don't use direct mode below 1024 x 768 (irqs don't fire) */
        if (size < DIRECT_FETCH_THRESHOLD) {
                aspeed_video_write(video, VE_TGS_0,
@@ -842,13 +863,6 @@ static void aspeed_video_set_resolution(struct aspeed_video *video)
                aspeed_video_update(video, VE_CTRL, 0, VE_CTRL_DIRECT_FETCH);
        }
 
-       /* Set capture/compression frame sizes */
-       aspeed_video_write(video, VE_CAP_WINDOW,
-                          act->width << 16 | act->height);
-       aspeed_video_write(video, VE_COMP_WINDOW,
-                          act->width << 16 | act->height);
-       aspeed_video_write(video, VE_SRC_SCANLINE_OFFSET, act->width * 4);
-
        size *= 4;
 
        if (size != video->srcs[0].size) {