Hi Geert,
Thanks for the feedback.
> Subject: Re: [PATCH v2 2/3] tty: serial: sh-sci: Add RZ/G2L SCIF DMA tx
> support
>
> Hi Biju,
>
> On Fri, Mar 24, 2023 at 11:02 AM Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> wrote:
> > Add SCIF DMA tx support for RZ/G2L alike SoCs.
> >
> > RZ/G2L alike SoC use the same signal for both interrupt and DMA
> > transfer requests, so we must disable line interrupts(tx and tx end)
> > while transferring DMA and enable the TIE source interrupt.
> >
> > Based on a patch in the BSP by Long Luu <long.luu.ur@xxxxxxxxxxx>
> >
> > Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
>
> Thanks for your patch!
>
> > --- a/drivers/tty/serial/sh-sci.c
> > +++ b/drivers/tty/serial/sh-sci.c
> > @@ -172,6 +172,13 @@ to_sci_port(struct uart_port *uart)
> > return container_of(uart, struct sci_port, port); }
> >
> > +static inline bool is_rz_scif_port(struct uart_port *port, struct
> > +sci_port *s) {
> > + const struct plat_sci_port *p = s->cfg;
> > +
> > + return port->type == PORT_SCIF && p->regtype ==
> > + SCIx_RZ_SCIFA_REGTYPE;
>
> The latter implies the former, so you can drop the first check.
> After that, the check becomes sufficiently simple to inline?
OK will remove this static inline function and will use cfg->regtype ==
SCIx_RZ_SCIFA_REGTYPE instead.
>
> > +}
> > +
> > static const struct sci_port_params sci_port_params[SCIx_NR_REGTYPES] = {
> > /*
> > * Common SCI definitions, dependent on the port's regshift @@
> > -588,6 +595,16 @@ static void sci_start_tx(struct uart_port *port)
> >
> > if (s->chan_tx && !uart_circ_empty(&s->port.state->xmit) &&
> > dma_submit_error(s->cookie_tx)) {
> > + if (is_rz_scif_port(port, s)) {
> > + /* Switch irq from SCIF to DMA */
> > + disable_irq(s->irqs[SCIx_TXI_IRQ]);
> > + disable_irq(s->irqs[SCIx_TEI_IRQ]);
As per Table 22.19 SCIFA Interrupt Sources, We don't need to
disable TEI as DMAC activation not possible with TEI.
> > +
> > + /* DMA need TIE enable */
> > + ctrl = serial_port_in(port, SCSCR);
> > + serial_port_out(port, SCSCR, ctrl |
> > + SCSCR_TIE);
>
> Enabling TIE is also done for SCIFA below (out of visible context).
> Perhaps you can combine?
OK.
>
> > + }
> > +
> > s->cookie_tx = 0;
> > schedule_work(&s->work_tx);
> > }
> > @@ -1214,9 +1231,16 @@ static void sci_dma_tx_complete(void *arg)
> > schedule_work(&s->work_tx);
> > } else {
> > s->cookie_tx = -EINVAL;
> > - if (port->type == PORT_SCIFA || port->type == PORT_SCIFB)
> {
> > + if (port->type == PORT_SCIFA || port->type == PORT_SCIFB
> ||
> > + is_rz_scif_port(port, s)) {
> > u16 ctrl = serial_port_in(port, SCSCR);
> > serial_port_out(port, SCSCR, ctrl &
> > ~SCSCR_TIE);
> > + if (port->type == PORT_SCIF) {
>
> "if (s->cfg->regtype == SCIx_RZ_SCIFA_REGTYPE)"?
Agreed.
>
> > + /* Switch irq from DMA to SCIF */
> > + dmaengine_pause(s->chan_tx_saved);
> > + enable_irq(s->irqs[SCIx_TXI_IRQ]);
> > + enable_irq(s->irqs[SCIx_TEI_IRQ]);
Will remove TEI as per the table, it is not required.
Cheers,
Biju
> > + }
> > }
> > }
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-
> m68k.org
>
> 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
