Hi Alan,
Thanks for your help, I might give this ago once I've
fixed some flow control problems in my driver.
On a loosely related topic I have extended
serial_core.c to handle DMA UARTS (only the TX path is
effected). Once I'm happy with my changes I post a
patch.
Best Regards,
Mark
--- Alan Cox <[email protected]> wrote:
> On Maw, 2005-07-26 at 10:55 +0100, Mark Underwood
> wrote:
> > What my driver would like to do is to handle its
> own
> > input buffers. It would pass the buffer to the tty
> > layer when it is full and the tty layer would pass
> the
>
> In theory you can do that already, although the
> locking is a bit screwed
> up for it. Actually all the tty locking is broken
> for rx I believe.
> Everyone should be holding the tty read lock when
> updating flip buffers
> but right now we don't
>
> > buffer back once it has drained the data from it.
> > The problem is that I don't always receive a block
> > worth of characters so I also need to pass the tty
> > layer a buffer (which I'm still DMAing into) with
> a
> > count of how many chars there are in the buffer
> and a
> > offset of where to start from.
>
> You can do this now providing you don't do it
> blindly from IRQ context.
>
> >From a workqueue do
>
> struct tty_ldisc *ld = tty_ldisc_ref(tty);
> int space;
>
> if(ld == NULL) /* Bin/defer */
> return;
> space = ld->receive_room(tty);
> if(count > space) count = space;
>
> ld->receive_buf(tty, charbuf, flagbuf, count);
>
>
> There is a corner case if TTY_DONT_FLIP is set where
> you should queue
> but not all drivers do this and the DONT_FLIP hack
> 'has to die'
>
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