https://bugs.freedesktop.org/show_bug.cgi?id=107835

Bug ID: 107835 Summary: DisplayPort audio stopped working in a kernel upgrade Product: DRI Version: unspecified Hardware: Other OS: All Status: NEW Severity: normal Priority: medium Component: DRM/AMDgpu Assignee: dri-devel@lists.freedesktop.org Reporter: bugs@benmorris.org.uk

In a recent kernel upgrade, my DisplayPort audio output stopped working. PulseAudio showed no available profiles for the device, while aplay appeared to work normally but produced no sound. I'm running Debian Unstable, and I have a Radeon RX 470.

I have bisected (in linux-stable), and narrowed down the start of the problem to this commit:

commit 9168c089a2122606e2c01f6fbeda85ff950ac189 (HEAD, refs/bisect/bad) Author: Alex Deucher alexander.deucher@amd.com Date: Tue Jul 10 12:56:45 2018 -0500

Revert "drm/amd/display: Don't return ddc result and read_bytes in same return value"

commit 5292221d6ddfed75e5b46cd42237a677094b99f3 upstream.

This reverts commit 018d82e5f02ef3583411bcaa4e00c69786f46f19.

This breaks DDC in certain cases. Revert for 4.18 and previous kernels. For 4.19, this is fixed with the following more extensive patches: drm/amd/display: Serialize is_dp_sink_present drm/amd/display: Break out function to simply read aux reply drm/amd/display: Return aux replies directly to DRM drm/amd/display: Right shift AUX reply value sooner than later drm/amd/display: Read AUX channel even if only status byte is returned

Link: https://lists.freedesktop.org/archives/amd-gfx/2018-July/023788.html Acked-by: Harry Wentland harry.wentland@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

I have tried kernel 4.19-rc2, and, as suggested in the commit message, the audio problem does indeed seem to be resolved in 4.19.

I have never seen the stacktrace associated with the same commit at https://bugzilla.kernel.org/show_bug.cgi?id=200667