Hi,
I independently hit this regression on a desktop Kaveri system and can
confirm this patch fixes it:
- AMD A10-7850K (Kaveri, DCE 8.1), MSI A68HM-E33, VGA monitor on the
onboard output (NUTMEG DP-to-VGA bridge)
- Debian kernel 7.1.3 (amdgpu.cik_support=1): VGA monitor receives no
signal from KMS takeover on; dmesg shows
"[drm] enabling link 2 failed: 15" (DC_FAIL_DP_LINK_TRAINING).
- Applying just this patch (1/2) on top of v7.1.3 restores VGA output
with DC enabled: the link trains, the CRTC comes up at 1360x768@60,
and the fix survived three consecutive reboots.
Tested-by: Lionso Alejandro Pacheco Vacacela <[email protected]>
Two notes:
1. The Fixes: tag references b74322eea36b, but that hash does not exist
in mainline — it looks like an amd-staging-internal id. In Linus'
tree the offending commit is:
a62346043a89 ("drm/amd/display: Fix coding style issue")
It would be good to correct this before the patch is pushed so the
stable tooling can resolve the dependency.
2. Since the offending commit shipped in v7.1, could this be annotated
Cc: [email protected] # 7.1.x (or nominated for 7.1.y once it
lands in mainline)? Every Kaveri/Kabini/Mullins system with a VGA
monitor loses display output on release kernels.
Thanks,
Lionso
