linux-kernel - Re: [PATCH] request_firmware: skip timeout if userspace was not notified

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Date:	Thu, 09 Aug 2007 11:36:05 +0200
From:	Javier Pello <javier.pello@...c.es>
To:	Cornelia Huck <cornelia.huck@...ibm.com>
CC:	Kay Sievers <kay.sievers@...y.org>, linux-kernel@...r.kernel.org,
	GregKH <greg@...ah.com>
Subject: Re: [PATCH] request_firmware: skip timeout if userspace was not 
	notified

On Tue, 07 Aug 2007, Cornelia Huck wrote:

> So it is indeed that this driver wants to fail its probe if it
> cannot get the firmware.

That's right. The driver unbinds itself from the device if it doesn't
get the firmware.

> A possibilty to achieve a similar effect would be to use
> request_firmware_nowait() and to call device_release_driver() from
> the callback if no firmware is loaded. (This would imply a split of
> that driver's probe function into two stages.)

The comments in the source code say that request_firmware_nowait()
is an "asynchronous version of request_firmware() for contexts where
it is not possible to sleep". So a driver's decision to call one of
them is not based on whether it wants to wait or not, but whether it
_can_ wait.

Of course, it can be decided that we never want to wait, but then
the best course of action would be to make request_firmware itself
behave as request_firmware_nowait (no need to change drivers).

Anyway, my point is that it is useless to have the kernel block for
a minute at boot waiting for something that cannot happen, and that
it should be avoided (even if my proposed solution is not the way
to go).

Javier

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