[Bug 79408] [HD Graphics 3000] frequent black screen on HDMI output

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=79408

Chris Wilson <chris at chris-wilson.co.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEEDINFO                    |NEW

--- Comment #4 from Chris Wilson <chris at chris-wilson.co.uk> ---
(In reply to comment #3)
> Thank you for taking time to respond.
> 
> I forgot to mention that I've installed an older ddx to see if the problem
> goes away. Now, i'm back with the most current version available in my
> distro (gentoo) :
> 
> [598382.917] (II) Module intel: vendor="X.Org Foundation"
> [598382.917]    compiled for 1.15.0, module version = 2.99.911
> [598382.917]    Module class: X.Org Video Driver
> [598382.917]    ABI class: X.Org Video Driver, version 15.0
> 
> Also, I disabled TearFree. As a result, I now seeing tearing in the upper
> part of the screen, and I still got the frequent black screen :(

That rules out a known bug as being the root cause. So onto the EDID.

> Is it normal to see the EDID checksum errors ?

It is infrequent. They do happen transiently with glitchy hardware, typically
cables. (More often you have machines/monitors where the EDID are always wrong,
i.e. bad firmware.)

> If I take the EDID that is dumped in the Xorg log, it is okay (checksum ok,
> correct infos displayed). But I also see a some lines like that in the dmesg
> output (some = 25 times in a 7 days uptime)

The EDID is used to check that there is a valid connection to the monitor, and
the connection is checked periodically (it should only happen as a result of a
hotplug event from the hardare). The EDID is re-read if corruption is detected,
so it may not be fatal, but if no valid EDID is found, it will be assumed that
the display is disconnected and will be turned off. If you have a static
configuration, you may like to try e.g. drm_kms_helper.edid=HDMI-A-1:my.edid
(and cp /sys/class/drm/card0-HDMI-A-1/edid /lib/firmware/my.edid)

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