From: Marcel Holtmann <marcel@holtmann.org>
To: BlueZ development <bluez-devel@lists.sourceforge.net>
In-Reply-To: <1175170710.15698.156.camel@cookie.hadess.net>
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Date: Thu, 29 Mar 2007 14:20:37 +0200
Message-Id: <1175170837.5815.194.camel@violet>
Mime-Version: 1.0
Subject: Re: [Bluez-devel] hcid returning "Device or resource busy"?
Reply-To: BlueZ development <bluez-devel@lists.sourceforge.net>
Content-Type: text/plain; charset="us-ascii"
Sender: bluez-devel-bounces@lists.sourceforge.net
Errors-To: bluez-devel-bounces@lists.sourceforge.net

Hi Bastien,

> > > > the problem is that the baseband is busy with the remote name request.
> > > > It has to page the remote device for getting the name and in that case
> > > > you simply can't run an inquiry. All currently available Bluetooth chips
> > > > have this limitation.
> > > > 
> > > > Main question is why we have the remote name request just before you
> > > > wanna start the inquiry. What D-Bus methods are you actually calling in
> > > > what order? I think you constructed a use case that we never tested.
> > > 
> > > The code is fairly straight forward. See:
> > > http://svn.gnome.org/viewcvs/nautilus-sendto/trunk/src/plugins/bluetooth.c?view=markup
> > > 
> > > The code first does a ListRemoteDevices (to list all the known, visible,
> > > etc.) devices in add_known_devices_to_list(), and then runs an discovery
> > > using DiscoverDevices in start_device_scanning().
> > > 
> > > Nothing mind blowing. I want to show all the known devices first (ie.
> > > the ones in the databases), and then add the devices
> > > visible/discoverable when the application is launched.
> > > 
> > > Is ListRemoteDevices actually doing anything on the HCI? I was under the
> > > impression that it should only pull items from the disk...
> > 
> > I almost guessed it. The ListRemoteDevices is not the problem the
> > GetRemoteName is the tricky part here. If the name is not in the cache
> > it tries to resolve it and this causes the baseband page which will
> > block the inquiry call.
> 
> Shouldn't it return org.bluez.Error.InProgress instead in that case?

it is a different operation that is in progress.

> > You can wait for the completed RemoteNameUpdated or RemoteNameFailed
> > signals before actually starting the DiscoverDevices procedure. However
> > in case of devices out of range this might not be a good idea.
> 
> The problem is that I don't know for which devices hcid will try to go
> and fetch the names for.
> 
> Also, the doc for ListRemoteDevices should mention the fact that it
> might perform remote operations, as it's not really clear from the doc
> right now.

Actually ListRemoteDevices is not doing it. It happens when you call
GetRemoteName while you are adding it to your list.

Regards

Marcel


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