From bb24153a3f13dd0dbc1f8055ad97fe346d598f66 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Wed, 25 Jul 2018 15:41:55 +0200 Subject: 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 Cc: stable@vger.kernel.org Signed-off-by: Bartlomiej Zolnierkiewicz --- include/video/udlfb.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/video') 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 */ -- cgit v1.2.3-59-g8ed1b