Return-Path: <cyrus@holtmann.org>
Subject: Re: PATCHES: Device discovery of the "bluetooth" CUPS backend does
 not work
From: Bastien Nocera <hadess@hadess.net>
To: Till Kamppeter <till.kamppeter@gmail.com>
Cc: linux-bluetooth@vger.kernel.org, Tim Waugh <twaugh@redhat.com>
In-Reply-To: <4A8153D9.4020008@gmail.com>
References: <4A8080DC.2010204@gmail.com>
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	 <4A8153D9.4020008@gmail.com>
Content-Type: text/plain
Date: Tue, 11 Aug 2009 12:33:58 +0100
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Sender: linux-bluetooth-owner@vger.kernel.org
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On Tue, 2009-08-11 at 13:19 +0200, Till Kamppeter wrote:
> Bastien Nocera wrote:
> >> Therefore I have modified /etc/dbus-1/system.d/bluetooth.conf 
> >> to grant this permission.
> >>
> >> I have added the following lines into the <busconfig> section:
> >>
> >>
> >>    <!-- allow users of lp group (printing subsystem) to communicate with 
> >> hcid -->
> >>    <policy group="lp">
> >>      <allow send_destination="org.bluez"/>
> >>    </policy>
> > 
> > Looks good. What about patching the upstream config file instead?
> > 
> 
> This is my intention, is it another file than 
> /etc/dbus-1/system.d/bluetooth.conf? I simply want nothing more than 
> that the access permission for "lp" is there out-of-the-box.

You're modifying a file in the Ubuntu package (it's in the debian/
sub-directory), not the one from bluez (src/bluetooth.conf in the
sources).

> >> Second, the output of the CUPS Bluetooth backend was not very good for 
> >> the printer setup tools doing the right thing. I have patched the 
> >> backend to let the device class of the Bluetooth printers to be "direct" 
> >> and not "network", as users expect a Bluetooth printer rather under the 
> >> local printers than under the network printers.
> > 
> > That seems like a good idea, but I don't know enough about the internals
> > of CUPS to know whether it changes anything but the classification of
> > the printer.
> > 
> > If it doesn't change the behaviour wrt. errors and retries, then I'm
> > fine with it.
> >
> 
> The device class only appears in the output of the backends in discovery 
> mode. It does not enter anywhere into the configuration of the print 
> queue. So it seems only to server for separating local and network 
> printers in the listing of detected printers in a printer setup tool.
> 
> A Bluetooth printer has to get paired with a computer before the 
> Bluetooth CUPS backend can find it.

I know that, seeing as I wrote the discovery code in the bluetooth
backend :)

>  This makes it getting assigned to 
> one single computer, whereas a network printer (Ethernet or WLAN) gets 
> discovered by all computers in the network and all computers can have a 
> working queue accessing to the same network printer. Therefore a 
> Bluetooth printer has more the characteristics of a local printer.

Seems fair.

> >>  I have also filled the 
> >> make-and-model field instead of putting a hard-coded "Unknown" there. 
> >> The change is here:
> > 
> > This part is broken. The backend man page says those are possible types
> > of output:
> > device-class scheme "Unknown" "device-info"
> > device-class device-uri "device-make-and-model" "device-info"
> > device-class device-uri "device-make-and-model" "device-info" "device-id"
> > device-class device-uri "device-make-and-model" "device-info" "device-id" "device-location"
> > 
> > So if you have the device-id, you must have a device-info. Your patch
> > removes the device-info even if we have a device-id.
> > 
> 
> Really? What I did is replacing the "Unknown" by "%s" and adding a 
> second "expanded" for the additional "%s". I have tested it and it works 
> as expected.
> 
> This is the output with my patch:
> 
> direct bluetooth://001A0E1769AA "Officejet H470" "Officejet H470 
> (Bluetooth)" "MFG:HP;MDL:Officejet 
> H470_BT;CMD:PCL,DW-PCL,DESKJET,DYN;CLS:PRINTER;DES:CB028A;"
> 
> It has exactly the 5 items as the second last line of the output schemes 
> which you show above shows.

You're right, read the patch in reverse...

> > In the future, please attach the patches to your mail, and make sure
> > they apply to the upstream sources.
> 
> Sorry, was my first patch submission to this project.

Could you rebase your fixes into patches ready for inclusion in the git
tree? If you don't know git, I'll make those changes myself.

> Do you have a bug/feature request tracking system?

There isn't one.