On Mon, Apr 30, 2012 at 12:37 AM, Dmitry Torokhov
<dmitry.torokhov at gmail.com> wrote:
> On Sat, Apr 28, 2012 at 11:33:50AM -0400, Nick Bowler wrote:
>> On 2012-04-28 02:19 -0400, Alex Deucher wrote:
>> > On Fri, Apr 27, 2012 at 8:39 PM, Nick Bowler <nbowler at elliptictech.com> 
>> > wrote:
>> > > Hi Ben,
>> > >
>> > > On 2012-04-27 15:20 +1000, Ben Skeggs wrote:
>> > >> Does this patch help you at all?
>> > >>
>> > >> http://cgit.freedesktop.org/nouveau/linux-2.6/commit/?id=a3a285f17867f0018de798b5ee85731ec1268305
>> > >
>> > > Yes. ?I cherry-picked this patch on top of Linus' master (3.4-rc4+) and
>> > > this appears to solve the "black screen on VGA" problem described in the
>> > > original report. ?Thanks!
>> > >
>> > > Unfortunately, that's not the end of my VGA-related regressions. :(
>> > >
>> > > While tracking down the black screen issue, I've been having the monitor
>> > > directly connected to the video card the whole time, but now when I'm
>> > > connected through my KVM switch (an IOGear GCS1804), it appears that
>> > > something's going wrong with reading the EDID, because the available
>> > > modes are all screwed up (both console and X decide they want to drive
>> > > the display at 1024x768). ?Here's the output of xrandr on 3.2.15:
>> > >
>> > > ?% xrandr
>> > > ?Screen 1: minimum 320 x 200, current 1600 x 1200, maximum 4096 x 4096
>> > > ?VGA-1 connected 1600x1200+0+0 (normal left inverted right x axis y 
>> > > axis) 352mm x 264mm
>> > > ? ? 1600x1200 ? ? ?75.0*+ ? 70.0 ? ? 65.0 ? ? 60.0
>> > > ? ? 1280x1024 ? ? ?85.0 + ? 75.0 ? ? 60.0
>> > > ? ? 1920x1440 ? ? ?60.0
>> > > ? ? 1856x1392 ? ? ?60.0
>> > > ? ? 1792x1344 ? ? ?60.0
>> > > ? ? 1920x1200 ? ? ?74.9 ? ? 59.9
>> > > ? ? 1680x1050 ? ? ?84.9 ? ? 74.9 ? ? 60.0
>> > > ? ? 1400x1050 ? ? ?85.0 ? ? 74.9 ? ? 60.0
>> > > ? ? 1440x900 ? ? ? 84.8 ? ? 75.0 ? ? 59.9
>> > > ? ? 1280x960 ? ? ? 85.0 ? ? 60.0
>> > > ? ? 1360x768 ? ? ? 60.0
>> > > ? ? 1280x800 ? ? ? 84.9 ? ? 74.9 ? ? 59.8
>> > > ? ? 1152x864 ? ? ? 75.0
>> > > ? ? 1280x768 ? ? ? 84.8 ? ? 74.9 ? ? 59.9
>> > > ? ? 1024x768 ? ? ? 85.0 ? ? 75.1 ? ? 75.0 ? ? 70.1 ? ? 60.0 ? ? 43.5 ? ? 
>> > > 43.5
>> > > ? ? 832x624 ? ? ? ?74.6
>> > > ? ? 800x600 ? ? ? ?85.1 ? ? 72.2 ? ? 75.0 ? ? 60.3 ? ? 56.2
>> > > ? ? 848x480 ? ? ? ?60.0
>> > > ? ? 640x480 ? ? ? ?85.0 ? ? 75.0 ? ? 72.8 ? ? 72.8 ? ? 66.7 ? ? 60.0 ? ? 
>> > > 59.9
>> > > ? ? 720x400 ? ? ? ?85.0 ? ? 87.8 ? ? 70.1
>> > > ? ? 640x400 ? ? ? ?85.1
>> > > ? ? 640x350 ? ? ? ?85.1
>> > > ? ? 320x200 ? ? ? 165.1
>> > >
>> > > And on 3.4-rc4+ (with your patch cherry-picked):
>> > >
>> > > ?% xrandr
>> > > ?Screen 1: minimum 320 x 200, current 1024 x 768, maximum 4096 x 4096
>> > > ?VGA-1 connected 1024x768+0+0 (normal left inverted right x axis y axis) 
>> > > 0mm x 0mm
>> > > ? ? 1024x768 ? ? ? 60.0*
>> > > ? ? 800x600 ? ? ? ?60.3 ? ? 56.2
>> > > ? ? 848x480 ? ? ? ?60.0
>> > > ? ? 640x480 ? ? ? ?59.9
>> > > ? ? 320x200 ? ? ? 165.1
>> > >
>> > > Running xrandr on 3.4-rc4+ also causes the screen to go black for a
>> > > second when it does not on 3.2.15. ?It also causes several messages of
>> > > the form
>> > >
>> > > ?[drm] nouveau 0000:01:00.0: Load detected on output B
>> > >
>> > > to be logged. ?Also, looking at /sys/class/drm/card0-VGA-1/edid I see
>> > > that it is empty on 3.4-rc4+ and it is correct on 3.2.15. ?Things seem
>> > > to work OK when the KVM is not involved.
>> >
>> > Were you ever able to fetch a EDID with the KVM involved? ?KVMs are
>> > notorious for not connecting the ddc pins.
>>
>> Yes, it works on 3.2.15 as described above.
>
> I have the same (or similar) KVM (not in the office at the moment) and I
> can confirm that with newer kernels EDID fecthing in flaky. It's 50/50
> if EDED retrieval succeeds or if it fails with:
>
> Apr 26 13:06:57 dtor-d630 kernel: [13464.936336] [drm:drm_edid_block_valid] 
> *ERROR* EDID checksum is invalid, remainder is 208
> Apr 26 13:06:57 dtor-d630 kernel: [13464.955317] [drm:drm_edid_block_valid] 
> *ERROR* EDID checksum is invalid, remainder is 208
> Apr 26 13:06:57 dtor-d630 kernel: [13464.973879] [drm:drm_edid_block_valid] 
> *ERROR* EDID checksum is invalid, remainder is 208
> Apr 27 09:13:03 dtor-d630 kernel: [44602.087659] [drm:drm_edid_block_valid] 
> *ERROR* EDID checksum is invalid, remainder is 208
> Apr 27 09:13:03 dtor-d630 kernel: [44602.107147] [drm:drm_edid_block_valid] 
> *ERROR* EDID checksum is invalid, remainder is 208
> Apr 27 09:13:03 dtor-d630 kernel: [44602.126908] [drm:drm_edid_block_valid] 
> *ERROR* EDID checksum is invalid, remainder is 208
> Apr 27 09:13:03 dtor-d630 kernel: [44602.146277] [drm:drm_edid_block_valid] 
> *ERROR* EDID checksum is invalid, remainder is 208
> Apr 27 09:13:03 dtor-d630 kernel: [44602.297659] [drm:drm_edid_block_valid] 
> *ERROR* EDID checksum is invalid, remainder is 208
> Apr 27 09:13:03 dtor-d630 kernel: [44602.317063] [drm:drm_edid_block_valid] 
> *ERROR* EDID checksum is invalid, remainder is 208
>
> Earlier kernels were able to retrieve EDEDs reliably.
>
> This is with:
>
> [ ? ?1.678392] [drm] nouveau 0000:01:00.0: Detected an NV50 generation card 
> (0x086b00a2)
>
> Thanks.
>
> --
> Dmitry
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> dri-devel at lists.freedesktop.org
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Just a crazy thought, but didn't we change some timings related to
EDID retrieval? To make it faster.

-- 
Far away from the primal instinct, the song seems to fade away, the
river get wider between your thoughts and the things we do and say.

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