linux-kernel - Re: bluetooth related firmware loader spew on resume.

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Message-ID: <1417012077.5928.11.camel@linux-0dmf.site>
Date:	Wed, 26 Nov 2014 15:27:57 +0100
From:	Oliver Neukum <oneukum@...e.de>
To:	Takashi Iwai <tiwai@...e.de>
Cc:	Marcel Holtmann <marcel@...tmann.org>,
	Dave Jones <davej@...hat.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	pgynther@...gle.com, linux-bluetooth@...r.kernel.org
Subject: Re: bluetooth related firmware loader spew on resume.

On Wed, 2014-11-26 at 15:12 +0100, Takashi Iwai wrote:
> At Wed, 26 Nov 2014 23:05:20 +0900,
> Marcel Holtmann wrote:
> > 
> > Hi Oliver,
> > 
> > >> In order to paper over this, we may also remember the failing firmware
> > >> and avoid loading it.  This might be an easer way than the endless
> > >> fight against UMH race...
> > > 
> > > 
> > > the full fix would be to implement reset_resume() for btusb.
> > > It seems to me that setup() should be split in two methods,
> > > one to request the firmware from user space and the second
> > > to transfer it to the device. reset_resume() would just need
> > > to repeat the second operation.
> > 
> > so when you do hci_register_dev, then hdev->setup is only called once. I really mean only once per lifetime of the hci_dev. So you would need to unregister the hci_dev first before hdev->setup will ever be called again. So I am not sure this is actually the problem here. The problem here is entirely within request_firmware() unless of course we run through the USB probe handlers again. Which I do not see happening here.
> > 
> > And we have hdev->setup this way since normally the Bluetooth devices keep their firmware patches and not forget about them and suspend-resume cycles. If the USB device of course jumps of the bus during it then all bets are off anyway.
> 
> Usually you can avoid unnecessary rebinding when you provide a proper
> reset_resume callback.  I guess that's what Oliver suggested.

Yes, but even in reset_resume() you would need to redo the setup
part, as the device lost power. The basic problem of requesting
the firmware wouldn't be solved.

	Regards
		Oliver


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