References: <20120102211904.GA15316@srcf.ucam.org> <CA+55aFwJuuvqcsgHnZ4-VhUhbVvL6beKogo1adgYyZt_ZM=H7A@mail.gmail.com> <20120102215028.GA15701@srcf.ucam.org> <CA+55aFz73GuHiOW1NoAuJLea_GKLepiZjrnrgpOKdQizPgnhoA@mail.gmail.com> <20120102221235.GA16012@srcf.ucam.org> <CA+55aFyHvmvast_kuNddU3iotReR1mOpKM4HGAw80ma8kn+2-g@mail.gmail.com> <20120102222920.GA16160@srcf.ucam.org> <CA+55aFyUK6X7ip2UXV9iT07=qezXfbw82wn6UKAN8JFQtYNs5Q@mail.gmail.com> <20120102230037.GA16458@srcf.ucam.org> <4F023E6B.2020307@fastmail.fm> <20120103001356.GA17183@srcf.ucam.org>
In-Reply-To: <20120103001356.GA17183@srcf.ucam.org>
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Subject: Re: loading firmware while usermodehelper disabled.
From: Jack Stone <jwjstone@fastmail.fm>
Date: Tue, 03 Jan 2012 00:22:58 +0000
To: Matthew Garrett <mjg@redhat.com>
CC: Linus Torvalds <torvalds@linux-foundation.org>,
	Alan Stern <stern@rowland.harvard.edu>,
	Oliver Neukum <oliver@neukum.org>,
	Dave Jones <davej@redhat.com>,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	Larry Finger <Larry.Finger@lwfinger.net>,
	Chaoming Li <chaoming_li@realsil.com.cn>,
	"John W. Linville" <linville@tuxdriver.com>,
	Greg Kroah-Hartman <gregkh@suse.de>,
	USB list <linux-usb@vger.kernel.org>,
	Linux Wireless List <linux-wireless@vger.kernel.org>
Message-ID: <8e95c7e3-e9d5-43c4-8e6a-b8d40584cbd6@email.android.com> (sfid-20120103_012318_253293_76425757)
Sender: linux-wireless-owner@vger.kernel.org


Matthew Garrett <mjg@redhat.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

-- 
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