Plans for hal 0.5.x

Andrei Yurkevich urruru at
Tue Dec 14 06:35:49 PST 2004

David Zeuthen wrote:
> On Tue, 2004-12-14 at 03:16 +0300, Andrei Yurkevich wrote:
>>I'd like to comment on PDAs here. There's been a discussion about
>>merging properties for Palm PDAs here recently, and I am working on
>>pretty much the same but for Pocket PC devices right now. What I would
>>like to know is whether the specifications for PDA properties have ever
>>been discussed here? I think that since different PDA platforms are in
>>fact very much alike when it comes to hardware we could treat them the
>>same way where possible. In any way, if David M. has already
>>decided/implemented anything regarding Palm PDAs in HAL, can some brief
>>overview be posted here?
> There was some discussion here
> but we never really got around to implementing anything. Personally, I
> fell that I lack the overview of the different pda devices to build an
> abstraction around it. 
> My gut feeling is that most USB-based pda's just have a USB serial
> adapter stuck onto them and in that case it would suffice with just
> tagging that USB device as 'pda' through device information files. I
> could be wrong though. 

Right, at least all PDAs I've seen (and that's been a lot of them) that 
connect via USB are built this way. They provide some USB device of 
their own that has got a USB-serial converter bound to that USB 
interface. However, in the discussion you've mentioned, the idea was to 
tag that USB device as a PDA. That's ok in case of USB, but when you 
connect a PDA via serial/IrDA or Bluetooth, you won't have that USB 
interface device. Instead, you will get a ttyS(n) in case of serial 
connection, rfcomm(n) for bluetooth and irtty(n) or ircomm(n) for IrDA, 
all of those being serial interfaces. Moreover, there is a way to 
distinguish the device connected via these serial interfaces as a PDA or 
something else, that could be done by HAL itself or a callout. Thus, we 
could simply tag these serial interfaces with some property like 
"pda.palm.serial_interface" or "pda.pocket_pc.serial_interface" just to 
let the interested applications know that these serial ports lead to a 
PDA device. Finally, some callout/daemon/whatever responsible for 
establishing a connection with a PDA could do what it needs to when it 
sees that there is a PDA available behind some serial interface.

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