Re: may I commit this small umodem patch ?

On Saturday 05 July 2008, Bernd Walter wrote:
> On Sat, Jul 05, 2008 at 09:57:06AM +0200, Hans Petter Selasky wrote:
> > On Saturday 05 July 2008, Luigi Rizzo wrote:
> > > On Sat, Jul 05, 2008 at 12:28:47AM +0200, Hans Petter Selasky wrote:
> > > > On Friday 04 July 2008, Luigi Rizzo wrote:
> > > > > On Fri, Jul 04, 2008 at 11:33:15PM +0200, Hans Petter Selasky wrote:
> > > > > > On Thursday 03 July 2008, Luigi Rizzo wrote:
> > > > > > > On Thu, Jul 03, 2008 at 05:07:00PM +0200, Gary Jennejohn wrote:
> > > > > > > > On Thu, 3 Jul 2008 16:07:19 +0200
> > > > > > > >
> > > > > > > > Luigi Rizzo <rizzo_at_icir.org> wrote:
> > > > > > > > > There was a discussion back in september about adding
> > > > > > > > > support for basic CDC tty devices in umodem.c.
> > > > > > > > > This lets you talk to a number of usb devices built around
> > > > > > > > > microcontrollers (e.g. Atmel), and puts us on par with
> > > > > > > > > Linux and Windows in terms of supporting these devices.
> > > > > > > > >
> > > > > > > > > Because this simply requires the small patch below to the
> > > > > > > > > probe/attach routine, so if there are no objections I plan
> > > > > > > > > to add this to the system (CURRENT then RELENG_7 and
> > > > > > > > > RELENG_6) in the next few days.
> > > > > >
> > > > > > What about flow control? Is flow control required for these
> > > > > > devices?
> > > > >
> > > > > the ones I am talking about don't implement any form of flow
> > > > > control. I suppose they would otherwise match the previous check.
> > > > >
> > > > > luigi
> > > >
> > > > I mean, are you going to upload firmware through these interfaces?
> > >
> > > the OS only know about bytes.
> > >
> > > are firmware, software, data or random noise.
> > > if you want to know whether the sam7 uploader works, yes it does.
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> >
> > Yes, but you know that umodem can drop data, if the buffers overflow ?
>
> Do you mean the driver can loose data?
> It would be good if this is avoidable somehow.
> In fact those beasts have some kind of pseudo flow control in that they
> don't ack further packets.
> Basicly this is nothing more than using a pair of bulk pipes for raw
> data, but under the hood of CDC identification.
> I personally only use them for uploading firmware to AT91SAM7*
> controllers, as luigi does, but since Windows and Linux have generic
> drivers this is quite popular.

From what I know the TTY layer which umodem uses will dump data when the 
buffers are full. But it there is some kind of framing in the protocol used, 
then this is no problem.

--HPS