On Fri, 2016-08-26 at 16:51 +0300, Matwey V. Kornilov wrote:
> 2016-08-26 15:49 GMT+03:00 Andy Shevchenko <andriy.shevchenko@xxxxxxxx
> tel.com>:
> >
> > There are calls to serial8250_rpm_{get|put}() in
> > __do_stop_tx_rs485() that are
> > certainly placed in a wrong location. I dunno how it had been tested
> > with
> > runtime PM enabled because it is obvious "sleep in atomic context"
> > error.
> >
> > Besides that serial8250_rpm_get() is called immediately after an IO
> > just
> > happened. It implies that the device is already powered on, see
> > implementation
> > of serial8250_em485_rts_after_send() and serial8250_clear_fifos()
> > for the
> > details.
> >
> > There is no bug have been seen due to, as I can guess, use of auto
> > suspend mode
> > when scheduled transaction to suspend is invoked quite lately than
> > it's needed
> > for a few writes to the port. It might be possible to trigger a
> > warning if
> > stop_tx_timer fires when device is suspended.
> >
> > Refactor the code to use runtime PM only in case of timer function.
> > --- a/drivers/tty/serial/8250/8250_port.c
> > +++ b/drivers/tty/serial/8250/8250_port.c
> > @@ -1414,12 +1414,8 @@ static void __do_stop_tx_rs485(struct
> > uart_8250_port *p)
> > if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX)) {
> > serial8250_clear_fifos(p);
> >
> > - serial8250_rpm_get(p);
> > -
> > p->ier |= UART_IER_RLSI | UART_IER_RDI;
> > serial_port_out(&p->port, UART_IER, p->ier);
> > -
> > - serial8250_rpm_put(p);
>
> This has been introduced by 0c66940d584d1aac92f6a78460dc0ba2efd3b7ba
> Don't you mind add corresponding Fixes tag?
I wouldn't mind, though I wonder if the fix doesn't break anything, so
Tested-by tags will be appreciated.
>
> Fixes: 0c66940d584d ("tty/serial/8250: fix RS485 half-duplex RX")
>
> And I would like also
>
> Cc: Yegor Yefremov <yegorslists@xxxxxxxxxxxxxx>
--
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy
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