linux-kernel - Re: loading firmware while usermodehelper disabled.

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Message-ID: <8e95c7e3-e9d5-43c4-8e6a-b8d40584cbd6@email.android.com>
Date:	Tue, 03 Jan 2012 00:22:58 +0000
From:	Jack Stone <jwjstone@...tmail.fm>
To:	Matthew Garrett <mjg@...hat.com>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Alan Stern <stern@...land.harvard.edu>,
	Oliver Neukum <oliver@...kum.org>,
	Dave Jones <davej@...hat.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Larry Finger <Larry.Finger@...inger.net>,
	Chaoming Li <chaoming_li@...lsil.com.cn>,
	"John W. Linville" <linville@...driver.com>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	USB list <linux-usb@...r.kernel.org>,
	Linux Wireless List <linux-wireless@...r.kernel.org>
Subject: Re: loading firmware while usermodehelper disabled.



Matthew Garrett <mjg@...hat.com> wrote:

>On Mon, Jan 02, 2012 at 11:31:55PM +0000, Jack Stone wrote:
>
>> Rather than merging the drivers we could make the uvcvideo (or any
>other
>> generic driver) driver expose a "subdriver" interface that allows
>> another module to bind to the specific ID and add extra handling to
>> certain events. We could then use that interface to provide a
>firmware
>> driver for each device that needs it. The firmware driver could bind
>to
>> the bootstrap device and to the uvcvideo subdriver interface and it
>> would then have all the lifetime info we need. [Credit to Linus for
>> suggesting this idea]
>
>No, the uvcvideo driver would need to call out to load the firmware 
>loader driver, otherwise you'll never know to load the firmware loader 
>driver.

So we have a table of USB ids that list the devices that need firmware drivers. When the uvcvideo driver registers the firmware interface with a USB id that matches the list we load the firmware driver and pass it a "warm start" event so it can cache the firmware.

As long as we can identify the devices that *might* need firmware then we are ok.

Thanks,

Jack

-- 
Sent from my Android phone with K-9 Mail. Please excuse my brevity.
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