linux-kernel - Re: [PATCH 1/3] drivers-gpu-drm-allow-to-load-edid-firmware.patch

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Date:	Wed, 25 Apr 2012 02:30:32 -0000
From:	Michael Witten <mfwitten@...il.com>
To:	Carsten Emde <C.Emde@...dl.org>
Cc:	Alan Cox <alan@...rguk.ukuu.org.uk>,
	David Airlie <airlied@...ux.ie>,
	Thomas Gleixner <tglx@...utronix.de>,
	DRI <dri-devel@...ts.freedesktop.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] drivers-gpu-drm-allow-to-load-edid-firmware.patch

On Sun, 11 Mar 2012 22:23:22 +0100, Carsten Emde wrote:

> On 03/11/2012 02:44 PM, Alan Cox wrote:
>
>>> This patch allows to load an EDID data set via the firmware interface.
>>> It contains data sets of frequently used screen resolutions (1024x768,
>>> 1280x1024, 1680x1050 and 1920x1080). The requested EDID data are
>>> specified as a module parameter of the drm_kms_helper module, e.g.
>>> options drm_kms_helper edid_firmware=edid/1280x1024.bin or as kernel
>>> command line parameter.
>>
>> What if the DRM layer and driver are compiled in. They'll come up as
>> console before the file system so the firmware request will hang ?
>
> Admittedly I did not try to compile the DRM layer and driver into the 
> kernel. However, I created an error condition by specifying a 
> non-existing EDID file. In this case, the function returns with error, 
> the mode count remains 0, and the system continues to run as if the 
> edid_firmware= parameter had not been specified.

Unfortunately, as of at least last month, my system hangs when I try to
use your feature (just as described by Alan Cox); the log shows that
during the boot process, there is a one-minute hang:

  [    0.175207] [drm] radeon: power management initialized
  [   60.896507] [drm:edid_load] *ERROR* Requesting EDID firmware "edid/1920x1200.bin" failed (err=-2)

Is there any way to make your feature smarter about its timing with
relation to file system accessibility?

Sincerely,
Michael Witten
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