Message-ID: <20141214224138.GA11447@amd>
Date:	Sun, 14 Dec 2014 23:41:38 +0100
From:	Pavel Machek <pavel@....cz>
To:	Marcel Holtmann <marcel@...tmann.org>
Cc:	Pali Rohár <pali.rohar@...il.com>,
	Sebastian Reichel <sre@...ian.org>,
	Sebastian Reichel <sre@...g0.de>,
	kernel list <linux-kernel@...r.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	linux-omap <linux-omap@...r.kernel.org>,
	Tony Lindgren <tony@...mide.com>, khilman@...nel.org,
	Aaro Koskinen <aaro.koskinen@....fi>,
	Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>,
	linux-bluetooth@...r.kernel.org
Subject: Re: bluetooth: Add hci_h4p driver

Hi!

> >>> Hacks surrounding bluetooth address were removed; this results in
> >>> working driver with address that is probably not unique.
> >> 
> >> Just set HCI_QUIRK_INVALID_BDADDR and let someone deal with that in userspace. You can use the btmgmt public-addr command for testing.
> >> 
> > 
> > Ok, it took me a while to figure out that --enable-experimental is
> > needed.
> > 
> > Then help was playing tricks with me:
> > 
> > For more information on the usage of each command use:
> >    btmgmt <command> --help
> > root@...0:/my/bluez-5.26/tools# ./btmgmt public-addr --help
> > Set Public Address for hci0 failed with status 0x0b (Rejected)
> > root@...0:/my/bluez-5.26/tools# ./btmgmt public-addr
> > Usage: btmgmt public-addr <address>
> 
> that is indeed confusing. Something went wrong with that tool. Just keep in mind that tool is just for internal testing by the developers. Someone would still need to write a proper integration with listening for the appropriate events and dig out the actual address from the memory location.
>

You have patch that helps that issues in the email :-).

> > root@...0:/my/bluez-5.26/tools# ./btmgmt public-addr 01:02:03:04:05:06
> > Set Public Address for hci0 failed with status 0x0b (Rejected)
> > 
> > Hmm. Since setting public address only works when interface is down,
> > and we lose all the settings during up, this does not work at all,
> > right?
> 
> It does keep it. The address is stored in hdev->public_addr which is actually different from hdev->bdaddr which is the current address in use.
> 
> However I am not sure that hdev->set_bdaddr is executed again. Same
> as hdev->setup is not executed twice. The controller loosing all
> states is something we have not yet encountered. At least not
> while the hci_dev stays around.

It looks like that's the exact issue. It seems to me like set_bdaddr
is actually called while the device is "down".

> I wonder if the drastic power off might be better hooked into a
> platform RFKILL switch. And with that you would just unregister
> hci_dev and re-register it when the RFKILL switch is unblocked.

Ok, so kernel currently wants bluetooth out of reset at 

> The other option is to introduce a quirk that allows running hdev->setup and hdev->set_bdaddr all the time when you bring up your device.
> 
> Another alternate idea for getting something upstream for testing is to ignore the whole firmware loading in the kernel and bring up the controller with HCI_QUIRK_EXTERNAL_CONFIG. Doing that would allow you to do bette testing and evolve the driver in small tests.
>

Actually, firmware loading is _not_ the biggest problem. That is
pretty self-contained now.

I guess I should just configure it at probe time, put it into reset
during rmmod, keep it out of reset otherwise, and see how it works.

Thanks,

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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