Bug 41366 - [r600 KMS] HDMI on a Fusion board only comes up when LVDS is already enabled
Summary: [r600 KMS] HDMI on a Fusion board only comes up when LVDS is already enabled
Status: NEW
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/Radeon (show other bugs)
Version: XOrg git
Hardware: x86 (IA32) Linux (All)
: medium normal
Assignee: Default DRI bug account
QA Contact:
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Reported: 2011-09-30 10:12 UTC by Simon Farnsworth
Modified: 2012-01-12 14:46 UTC (History)
0 users

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Attachments
dmesg showing the modeset that results in HDMI being off unexpectedly (16.63 KB, text/plain)
2011-09-30 10:13 UTC, Simon Farnsworth
no flags Details
dmesg showing the modeset that results in HDMI working (18.13 KB, text/plain)
2011-09-30 10:13 UTC, Simon Farnsworth
no flags Details
use hardcoded dig encoder to transmitter mapping (1.30 KB, patch)
2011-10-05 15:35 UTC, Alex Deucher
no flags Details | Splinter Review

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Description Simon Farnsworth 2011-09-30 10:12:18 UTC
I'm running airlied's drm-fixes, git revision fdfc61594e6de21c23f955818ef78bcab9bafe40, and experiencing "interesting" times trying to get HDMI to work on a Fusion GPU (detected by X as [    49.876] (--) RADEON(0): Chipset: "AMD Radeon HD 6310 Graphics" (ChipID = 0x9802)).

If I run:
xrandr --output HDMI-0 --off
xrandr --output LVDS --auto
xrandr --output HDMI-0 --mode 1920x1200

the HDMI monitor comes up at 1920x1200

If I run:
xrandr --output HDMI-0 --off
xrandr --output LVDS --off
xrandr --output HDMI-0 --mode 1920x1200

the HDMI monitor immediately enters DPMS Off state, and stays there.

I've confirmed with "grep . /sys/class/drm/card0-HDMI-A-1/*" that the kernel thinks the HDMI connector is switched on. The only difference I can see is that HDMI works when it gets CRTC 1, but not when it gets CRTC 0.

I have captured logs from the kernel with drm.debug=0x6 during the runs, in case that explains what's going on; I will attach them to this bug.
Comment 1 Simon Farnsworth 2011-09-30 10:13:00 UTC
Created attachment 51804 [details]
dmesg showing the modeset that results in HDMI being off unexpectedly
Comment 2 Simon Farnsworth 2011-09-30 10:13:24 UTC
Created attachment 51805 [details]
dmesg showing the modeset that results in HDMI working
Comment 3 Alex Deucher 2011-10-05 15:08:22 UTC
Strange, everything looks correct.  I'll dig into it.  Manually specifying the crtc seems to work, e.g.,

xrandr --output HDMI-0 --mode 1920x1200 --crtc 1
xrandr --output HDMI-0 --mode 1920x1200 --crtc 0
Comment 4 Alex Deucher 2011-10-05 15:35:55 UTC
Created attachment 52024 [details] [review]
use hardcoded dig encoder to transmitter mapping

This patch fixes the issue for me.
Comment 5 Simon Farnsworth 2011-10-06 03:10:23 UTC
Tested the patch - it works for me.
Comment 6 Florian Mickler 2012-01-12 14:46:12 UTC
A patch referencing this bug report has been merged in Linux v3.1-rc10:

commit cb7cf41961fe10773c491c75ae73539ad4bbed66
Author: Alex Deucher <alexander.deucher@amd.com>
Date:   Wed Oct 5 18:36:50 2011 -0400

    drm/radeon/kms: use hardcoded dig encoder to transmitter mapping for DCE4.1


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