Hi Shimoda-san,
On Thu, Jun 10, 2021 at 2:50 AM Yoshihiro Shimoda
<yoshihiro.shimoda.uh@xxxxxxxxxxx> wrote:
> > From: Geert Uytterhoeven, Sent: Thursday, June 10, 2021 12:30 AM
> > On Wed, Jun 9, 2021 at 5:09 PM Sergei Shtylyov
> > <sergei.shtylyov@xxxxxxxxx> wrote:
> > > On 6/9/21 4:49 AM, Yoshihiro Shimoda wrote:
> > > > Stop dmaengine transfer in sci_stop_tx(). Otherwise, the following
> > > > message is possible output when system enters suspend and while
> > > > transferring data, because clearing TIE bit in SCSCR is not able to
> > > > stop any dmaengine transfer.
> > > >
> > > > sh-sci e6550000.serial: ttySC1: Unable to drain transmitter
> > > >
> > > > Note that this patch uses dmaengine_terminate_async() so that
> > > > we can apply this patch into longterm kernel v4.9.x or later.
> > > >
> > > > Fixes: 73a19e4c0301 ("serial: sh-sci: Add DMA support.")
> > > > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
> > > > ---
> > > >
> > > > drivers/tty/serial/sh-sci.c | 8 ++++++++
> > > > 1 file changed, 8 insertions(+)
> > > >
> > > > diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
> > > > index 4baf1316ea72..2d5487bf6855 100644
> > > > --- a/drivers/tty/serial/sh-sci.c
> > > > +++ b/drivers/tty/serial/sh-sci.c
> > > > @@ -610,6 +610,14 @@ static void sci_stop_tx(struct uart_port *port)
> > > > ctrl &= ~SCSCR_TIE;
> > > >
> > > > serial_port_out(port, SCSCR, ctrl);
> > > > +
> > > > +#ifdef CONFIG_SERIAL_SH_SCI_DMA
> > >
> > > Why not use IS_ENABLED() instead? Gets rid of #ifdef. :-)
> > >
> > > > + if (to_sci_port(port)->chan_tx &&
> > > > + !dma_submit_error(to_sci_port(port)->cookie_tx)) {
> > > > + dmaengine_terminate_async(to_sci_port(port)->chan_tx);
> > > > + to_sci_port(port)->cookie_tx = -EINVAL;
> >
> > Because chan_tx and cookie_tx do not exist if CONFIG_SERIAL_SH_SCI_DMA
> > is disabled.
>
> This is a nit though, chan_tx always exists.
I stand corrected, only cookie_tx depends on CONFIG_SERIAL_SH_SCI_DMA.
> > Yes, that's why all the DMA code in this driver (.c file) is protected by
> > #ifdef CONFIG_SERIAL_SH_SCI_DMA.
>
> I'm thinking we have to remove #ifdef from sh-sci.c file at first...
While I don't disagree that would be worthwhile, do we really need
to refactor a driver first, before a fix that follows the existing
driver style can be applied (and backported)?
Thanks!
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
