Hi,
* Jiri Slaby <jirislaby@xxxxxxxxxx> [200818 08:24]:
> On 17. 08. 20, 15:54, Tony Lindgren wrote:
> > If write returns zero we currently end up removing the message
> > from the queue. Instead of removing the message, we want to just
> > break out of the loop just like we already do for error codes.
>
> When exactly does the only writer (gsmld_output) return zero for
> non-zero len parameter?
I ran into this when testing with the WIP serial core PM runtime
changes from Andy Shevchenko earlier. If there are also other
cases where we have serial drivers return 0, I don't know about
them.
Basically with the WIP serial core changes, if the open serial port
is in PM runtime suspended state with it's autosuspend_delay_ms
expired, we have write return 0 and just wake up the serial device
on TX.
I don't think there's much anything else we can currently do there
in the PM runtime suspended case as we want to get rid of the
remaining pm_runtime_irq_safe() dependencies as it takes a permanent
usage count on the parent device.
Regards,
Tony
>
> > Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
> > ---
> > drivers/tty/n_gsm.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
> > --- a/drivers/tty/n_gsm.c
> > +++ b/drivers/tty/n_gsm.c
> > @@ -691,7 +691,8 @@ static void gsm_data_kick(struct gsm_mux *gsm, struct gsm_dlci *dlci)
> > print_hex_dump_bytes("gsm_data_kick: ",
> > DUMP_PREFIX_OFFSET,
> > gsm->txframe, len);
> > - if (gsm->output(gsm, gsm->txframe, len) < 0)
> > +
> > + if (gsm->output(gsm, gsm->txframe, len) <= 0)
> > break;
> > /* FIXME: Can eliminate one SOF in many more cases */
> > gsm->tx_bytes -= msg->len;
> >
>
> thanks,
> --
> js
