KMS/radeon regression: failure to set modes on CEDAR & TAHITI v3.11 vs 3.12-rc5/rc7

[Alex Deucher]

On Sun, Nov 3, 2013 at 4:41 AM, Robin H. Johnson <robbat2 at gentoo.org> wrote:
> I apologize for not sending this sooner, but I wanted to be really sure that I
> wasn't introducing the bug elsewhere, and I was lacking time to even narrow it
> down this far.
>
> TL;DR:
> 3.11 kernel does proper modeset for dual 1920x1200 outputs
> 3.12-rc5/rc7 kernel fails to do proper modeset, blank screen after radeon loaded
>

Can you bisect?

Alex


> Symptoms:
> - With implicit video= modes, after the radeon module loads, both monitors just go blank.
>   Kernel message: radeon 0000:01:00.0: No connectors reported connected with modes
>   X does not visible start, screen stays black.
> - With explicit video= modes, after the radeon module loads, both monitors during the
>   kernel boot display very garbled output; after X starts, they are in
>   1024x768, with no higher modes listed.
>
> Attached are four dmesg [1] runs, on v3.11 vs v3.12-rc7, with both explicit
> video parameters, and implicit video parameters; as well as drm.debug=0x06 in
> ALL cases; as well as two xorg logs (both from the implicit variants).
>
> testcase 1 (implicit): modeset=1 fbcon=map:0 drm.debug=0x06
> testcase 2 (explicit): video=HDMI-A-1:1920x1200e video=DVI-I-1:1920x1200e modeset=1 fbcon=map:0 drm.debug=0x06
>
> I have produced this bug with three different cards:
> CEDAR 0x1002:0x68F9 0x1043:0x03CA (used for all these bug reports)
> CEDAR 0x1002:0x68F9 0x174B:0xE164
> TAHITI 0x1002:0x6798 0x1458:0x2261 (7970, borrowed before)
>
> This happened as far back as 3.12-rc5 for me, but I didn't debug more at the
> time.
>
> Monitors:
> (Left) Dell U2410 via DVI
> (Center) Dell U2413 via HDMI
> (Right is another U2410, not connected at all)
>
> Userspace:
> xorg-server-1.14.3
> mesa-9.2.1
> xf86-video-ati-7.2.0
>
> I think the error might be and off by one in the connector probing, based on
> this:
>
> 3.11:
> [drm:drm_helper_probe_single_connector_modes], [CONNECTOR:15:HDMI-A-1]
> [drm:radeon_atombios_connected_scratch_regs], DFP1 connected
> [drm:drm_helper_probe_single_connector_modes], [CONNECTOR:15:HDMI-A-1] probed modes :
>
> 3.12-rc7:
> [drm:drm_helper_probe_single_connector_modes], [CONNECTOR:16:HDMI-A-1]
> [drm:radeon_process_i2c_ch], hw_i2c error
> [drm:radeon_atombios_connected_scratch_regs], DFP1 disconnected
> [drm:drm_helper_probe_single_connector_modes], [CONNECTOR:16:HDMI-A-1] disconnected
>
> [1] yes I know about the bonding error, that's a separate issue I need
> to mail to LKML/netdev.
>
> --
> Robin Hugh Johnson
> Gentoo Linux: Developer, Trustee & Infrastructure Lead
> E-Mail     : robbat2 at gentoo.org
> GnuPG FP   : 11ACBA4F 4778E3F6 E4EDF38E B27B944E 34884E85
>
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