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| author | Mikulas Patocka <mpatocka@redhat.com> | 2018-07-25 15:41:55 +0200 |
|---|---|---|
| committer | Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> | 2018-07-25 15:41:55 +0200 |
| commit | bb24153a3f13dd0dbc1f8055ad97fe346d598f66 (patch) | |
| tree | fbb89099971839d4da3fd909d0425ca9c6141942 | |
| parent | 2c29cfc3eaf11779176bf41475cfca49bccba11c (diff) | |
| download | lwn-bb24153a3f13dd0dbc1f8055ad97fe346d598f66.tar.gz lwn-bb24153a3f13dd0dbc1f8055ad97fe346d598f66.zip | |
udlfb: set optimal write delay
The default delay 5 jiffies is too much when the kernel is compiled with
HZ=100 - it results in jumpy cursor in Xwindow.
In order to find out the optimal delay, I benchmarked the driver on
1280x720x30fps video. I found out that with HZ=1000, 10ms is acceptable,
but with HZ=250 or HZ=300, we need 4ms, so that the video is played
without any frame skips.
This patch changes the delay to this value.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
| -rw-r--r-- | include/video/udlfb.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/video/udlfb.h b/include/video/udlfb.h index b4f43d3ac1af..6e1a2e790b1b 100644 --- a/include/video/udlfb.h +++ b/include/video/udlfb.h @@ -88,7 +88,7 @@ struct dlfb_data { #define MIN_RAW_PIX_BYTES 2 #define MIN_RAW_CMD_BYTES (RAW_HEADER_BYTES + MIN_RAW_PIX_BYTES) -#define DL_DEFIO_WRITE_DELAY 5 /* fb_deferred_io.delay in jiffies */ +#define DL_DEFIO_WRITE_DELAY msecs_to_jiffies(HZ <= 300 ? 4 : 10) /* optimal value for 720p video */ #define DL_DEFIO_WRITE_DISABLE (HZ*60) /* "disable" with long delay */ /* remove these once align.h patch is taken into kernel */ |