]> git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/commit
drm/amd/display: Add retry to read ddc_clock pin
authorPaul Hsieh <paul.hsieh@amd.com>
Thu, 22 Nov 2018 10:43:45 +0000 (18:43 +0800)
committerKleber Sacilotto de Souza <kleber.souza@canonical.com>
Wed, 14 Aug 2019 09:18:49 +0000 (11:18 +0200)
commit60afc43cc05a2ec3780dd361afa182f56b38cae5
treecc6804caaf4a0ec9e2be4714817cbefff2b2d9e6
parent7f0111640ba160ba79a49dd491eab10b52ce4340
drm/amd/display: Add retry to read ddc_clock pin

BugLink: https://bugs.launchpad.net/bugs/1837664
[ Upstream commit bd4905a9583c760da31ded7256dca6f71483c3dc ]

[WHY]
On customer board, there is one pluse (1v , < 1ms) on
DDC_CLK pin when plug / unplug DP cable. Driver will read
it and config DP to HDMI/DVI dongle.

[HOW]
If there is a real dongle, DDC_CLK should be always pull high.
Try to read again to recovery this special case. Retry times = 3.
Need additional 3ms to detect DP passive dongle(3 failures)

Signed-off-by: Paul Hsieh <paul.hsieh@amd.com>
Reviewed-by: Eric Yang <eric.yang2@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
drivers/gpu/drm/amd/display/dc/core/dc_link.c