Isaac Christensen (isaac.christensen@se-eng.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/6543
-gerrit
commit 8831279b0b83443a3be25dcebb9f36a62b063ebf Author: Ronald G. Minnich rminnich@gmail.com Date: Thu Aug 29 09:16:25 2013 -0700
exynos5420: Tighten up displayport timing loops
We were running this loop 100 times with 5 ms delays. Change it to run 500 times with 1 ms delays, which gives us the same overall timeout but lets us bail out a bit sooner -- in practice, at most, 4 ms sooner but every bit counts. Note, however, that the tighter timing does reduce opportunities for threading. There is a non-obvious set of tradeoffs on timeouts.
Change-Id: I4af671c2a791aa92e446e66ac2fe5710d1e6aa4c Signed-off-by: Ronald G. Minnich rminnich@gmail.com Reviewed-on: https://chromium-review.googlesource.com/167387 Reviewed-by: David Hendricks dhendrix@chromium.org Commit-Queue: ron minnich rminnich@chromium.org Tested-by: ron minnich rminnich@chromium.org (cherry picked from commit 575e910127dc74416018f182ef27ef223e61daef) Signed-off-by: Isaac Christensen isaac.christensen@se-eng.com --- src/cpu/samsung/exynos5420/dp.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/src/cpu/samsung/exynos5420/dp.c b/src/cpu/samsung/exynos5420/dp.c index b6f83b6..c1fa17a 100644 --- a/src/cpu/samsung/exynos5420/dp.c +++ b/src/cpu/samsung/exynos5420/dp.c @@ -845,7 +845,7 @@ static unsigned int exynos_dp_config_video(struct edp_device_info *edp_info) exynos_dp_start_video();
if (edp_info->video_info.master_mode == 0) { - retry_cnt = 100; + retry_cnt = 500; while (retry_cnt) { ret = exynos_dp_is_video_stream_on(); if (ret != EXYNOS_DP_SUCCESS) { @@ -857,7 +857,10 @@ static unsigned int exynos_dp_config_video(struct edp_device_info *edp_info) printk(BIOS_DEBUG, "DP video stream is on\n"); break; } - mdelay(5); + /* this is a cheap operation, involving some register + * reads, and no AUX channel IO. A ms. delay is fine. + */ + mdelay(1); } }