"EDID checksum is invalid"

[Daniel Vetter]

On Wed, Jan 7, 2015 at 3:01 AM, Linus Torvalds
<torvalds at linux-foundation.org> wrote:
> So my el-cheapo UHD Dell monitor is unhappy with dmps, and just never
> wakes up from it.
>
> I work around it with just doing "xset -dpms" and it's not a big deal,
> but I thought I'd report it anyway, since there are actual debug
> messages, and maybe there's a better way to handle it. Does anybody
> have any idea of why it would do this:

Yeah if the edid probe fails userspace will get a hotplug and
autodisable the output. With a failsafe X session (just a dumb
terminal) we can avoid that to check that dpms on itself would work or
whether the edid probe fail here is just indicative of more trouble.
Also please boot with drm.debug=0xe, repro and grab dmesg, that might
shed some more light on what's failing.

Thanks, Daniel

>    [drm:drm_edid_block_valid [drm]] *ERROR* EDID checksum is invalid,
> remainder is 111
>    Raw EDID:
>     00 ff ff ff ff ff ff 00 10 ac 5c f0 4d 54 31 41
>     24 18 01 03 80 3e 22 78 ea 0a a5 a2 57 4f a2 28
>     0f 50 54 a5 4b 00 71 4f 81 00 81 80 a9 40 b3 00
>     d1 c0 d1 00 7f ff ff ff ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>
>    [drm:drm_edid_block_valid [drm]] *ERROR* EDID checksum is invalid,
> remainder is 240
>    Raw EDID:
>     00 ff ff ff ff ff ff 00 10 ac 5c f0 4d 54 31 41
>     24 18 01 03 80 3e 22 78 ea 0a a5 a2 57 4f a2 28
>     0f 50 54 a5 4b 00 71 4f 81 00 81 87 ff ff ff ff
>     ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>
>    [drm:drm_edid_block_valid [drm]] *ERROR* EDID checksum is invalid,
> remainder is 35
>    Raw EDID:
>     00 ff ff ff ff ff ff 00 10 ac 5c f0 4d 54 31 41
>     24 18 01 03 80 3e 22 78 ea 0a a5 a2 57 4f a2 28
>     0f 50 54 a5 4b 00 71 4f 81 00 81 80 a9 40 b3 00
>     d1 c7 ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>
>    [drm:drm_edid_block_valid [drm]] *ERROR* EDID checksum is invalid,
> remainder is 212
>    Raw EDID:
>     00 ff ff ff ff ff ff 00 10 ac 5c f0 4d 54 31 41
>     24 18 01 03 80 3e 22 78 ea 0a a5 a2 57 4f a2 28
>     0f 50 54 a5 4b 00 71 4f 81 00 81 80 a9 40 ff ff
>     ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>
> it looks like the beginning is the same, but then it just turns to all
> ones at a random point (even *within* a byte).
>
> Does anything spring to mind?
>
>                      Linus
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch