linux-kernel - Re: [PATCH] ALSA: hda - Defer probe when loading patch firmware

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Date:	Thu, 9 Aug 2012 09:08:13 +0200
From:	Thierry Reding <thierry.reding@...onic-design.de>
To:	Takashi Iwai <tiwai@...e.de>
Cc:	Jaroslav Kysela <perex@...ex.cz>,
	David Henningsson <david.henningsson@...onical.com>,
	alsa-devel@...a-project.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ALSA: hda - Defer probe when loading patch firmware

On Thu, Aug 09, 2012 at 08:57:13AM +0200, Takashi Iwai wrote:
> At Thu,  9 Aug 2012 08:45:23 +0200,
> Thierry Reding wrote:
> > 
> > Recent changes to the firmware loading helpers cause drivers to stall
> > when firmware is loaded during the module_init() call. The snd-hda-intel
> > module requests firmware if the patch= parameter is used to load a patch
> > file. This patch works around the problem by deferring the probe in such
> > cases, which will cause the module to load successfully and the driver
> > binding to the device outside the module_init() call.
> 
> Is the "recent" change meant 3.6 kernel, or in linux-next?
> 
> In anyway, I don't understand why such a change was allowed.  Most
> drivers do call request_firmware() at the device probing time.
> If this really has to be resolved in the driver side, it must be a bug
> in the firmware loader core code.

A good explanation of the problem and subsequent discussion can be found
here:

	http://article.gmane.org/gmane.linux.drivers.video-input-infrastructure/49975

Thierry

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