Re: [PATCH 4/5] tty: serial: 8250 core: add runtime pm

[Peter Hurley]

On 07/16/2014 12:06 PM, Felipe Balbi wrote:
> On Wed, Jul 16, 2014 at 05:54:56PM +0200, Sebastian Andrzej Siewior wrote:
> > On 07/16/2014 05:16 PM, Felipe Balbi wrote:

> > > I wonder if you should get_sync() on start_tx() and only
> > > put_autosuspend() at stop_tx(). I guess the outcome would be
> > > largely the same, no ?
> >
> > I just opened minicom on ttyS0 and gave a try. start_tx() was invoked
> > each time I pressed a key (sent a character). I haven't seen stop_tx()
> > even after after I closed minicom. I guess stop_tx() is invoked if you
> > switch half-duplex communication.
>
> that's bad, I expected stop to be called also after each character.

The 8250 core auto-stops tx when the tx ring buffer is empty (except
in the case of dma, where stopping tx isn't necessary).

Regards,
Peter Hurley
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