Re: [PATCH 6/7] tty/powerpc: introduce the ePAPR embedded hypervisor byte channel driver

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

On Thu, 19 May 2011 11:05:49 -0500
Timur Tabi <timur@freescale.com> wrote:

> Alan Cox wrote:
> >> > +		/* Pass the received data to the tty layer.  Note that this
> >> > +		 * function calls tty_buffer_request_room(), so I'm not sure if
> >> > +		 * we should have also called tty_buffer_request_room().
> >> > +		 */
> >> > +		ret = tty_insert_flip_string(ttys, buffer, len);
> 
> > You only need to request_room in advance if you can't handle the case
> > where the insert_flip_string returns less than you stuffed down it.
> 
> If tty_insert_flip_string() returns less than I stuffed down it, the characters
> it didn't accept will be dropped.  That's because once I receive them, I have
> nowhere else to put them.  I suppose I could implement a receive FIFO, but that
> seems overkill.  If calling tty_buffer_request_room() ensures that
> tty_insert_flip_string() always accepts all the characters, I would rather do that.

I was answering the question in the comment in the code...