Hi Geert,
Thanks for the feedback.
> Subject: Re: [PATCH v2 3/3] tty: serial: sh-sci: Add RZ/G2L SCIF DMA rx
> support
>
> Hi Biju,
>
> On Fri, Mar 24, 2023 at 11:02 AM Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> wrote:
> > Add SCIF DMA rx support for RZ/G2L alike SoCs.
> >
> > RZ/G2L alike SoCs use the same signal for both interrupt and DMA
> > transfer requests, so we must disable line interrupt while transferring
> DMA.
> >
> > We must set FIFO trigger to 1 so that SCIF will request DMA when there
> > is a character as SCIF DMA request is based on FIFO data full RDF.
> >
> > 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
> > @@ -1312,9 +1312,13 @@ static void sci_dma_rx_reenable_irq(struct
> > sci_port *s)
> >
> > /* Direct new serial port interrupts back to CPU */
> > scr = serial_port_in(port, SCSCR);
> > - if (port->type == PORT_SCIFA || port->type == PORT_SCIFB) {
> > - scr &= ~SCSCR_RDRQE;
> > + if (port->type == PORT_SCIFA || port->type == PORT_SCIFB ||
> > + is_rz_scif_port(port, s)) {
> > enable_irq(s->irqs[SCIx_RXI_IRQ]);
> > + if (port->type == PORT_SCIF)
> > + scif_set_rtrg(port, s->rx_trigger);
> > + else
> > + scr &= ~SCSCR_RDRQE;
> > }
> > serial_port_out(port, SCSCR, scr | SCSCR_RIE); } @@ -1735,7
> > +1739,15 @@ static irqreturn_t sci_rx_interrupt(int irq, void *ptr)
> > if (sci_dma_rx_submit(s, false) < 0)
> > goto handle_pio;
> >
> > - scr &= ~SCSCR_RIE;
> > + if (is_rz_scif_port(port, s)) {
> > + /* Switch irq from SCIF to DMA */
> > +
> > + disable_irq_nosync(s->irqs[SCIx_RXI_IRQ]);
>
> Perhaps this can be combined with the disable_irq_nosync() above?
OK, will do, As per Table 22.19 SCIFA Interrupt Sources, DMAC activation
Only possible with RXI interrupt.
So we need to use "s->irqs[SCIx_RXI_IRQ]" instead of "irq" for RZ/G2L SCIFA.
>
> > + scif_set_rtrg(port, 1);
> > + /* DMA need RIE enable */
> > + scr |= SCSCR_RIE;
> > + } else {
> > + scr &= ~SCSCR_RIE;
> > + }
>
> ... and this with some other SCIFA code path?
OK.
>
> Looks like RZ/A2 and RZ/G2L "SCIFA" does have some resemblance with SCIFA,
> contrary to earlier statements?
> Perhaps the code can be simplified by treating it even more like a SCIFA?
Yes, new patch looks like
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 367bdb913d4a..146409e44556 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1299,9 +1299,13 @@ static void sci_dma_rx_reenable_irq(struct sci_port *s)
/* Direct new serial port interrupts back to CPU */
scr = serial_port_in(port, SCSCR);
- if (port->type == PORT_SCIFA || port->type == PORT_SCIFB) {
- scr &= ~SCSCR_RDRQE;
+ if (port->type == PORT_SCIFA || port->type == PORT_SCIFB ||
+ s->cfg->regtype == SCIx_RZ_SCIFA_REGTYPE) {
enable_irq(s->irqs[SCIx_RXI_IRQ]);
+ if (s->cfg->regtype == SCIx_RZ_SCIFA_REGTYPE)
+ scif_set_rtrg(port, s->rx_trigger);
+ else
+ scr &= ~SCSCR_RDRQE;
}
serial_port_out(port, SCSCR, scr | SCSCR_RIE);
}
@@ -1538,7 +1542,8 @@ static enum hrtimer_restart sci_dma_rx_timer_fn(struct hrtimer *t)
tty_flip_buffer_push(&port->state->port);
}
- if (port->type == PORT_SCIFA || port->type == PORT_SCIFB)
+ if (port->type == PORT_SCIFA || port->type == PORT_SCIFB ||
+ s->cfg->regtype == SCIx_RZ_SCIFA_REGTYPE)
sci_dma_rx_submit(s, true);
sci_dma_rx_reenable_irq(s);
@@ -1662,7 +1667,8 @@ static void sci_request_dma(struct uart_port *port)
s->chan_rx_saved = s->chan_rx = chan;
- if (port->type == PORT_SCIFA || port->type == PORT_SCIFB)
+ if (port->type == PORT_SCIFA || port->type == PORT_SCIFB ||
+ s->cfg->regtype == SCIx_RZ_SCIFA_REGTYPE)
sci_dma_rx_submit(s, false);
}
}
@@ -1715,9 +1721,16 @@ static irqreturn_t sci_rx_interrupt(int irq, void *ptr)
u16 ssr = serial_port_in(port, SCxSR);
/* Disable future Rx interrupts */
- if (port->type == PORT_SCIFA || port->type == PORT_SCIFB) {
- disable_irq_nosync(irq);
- scr |= SCSCR_RDRQE;
+ if (port->type == PORT_SCIFA || port->type == PORT_SCIFB ||
+ s->cfg->regtype == SCIx_RZ_SCIFA_REGTYPE) {
+ if (s->cfg->regtype != SCIx_RZ_SCIFA_REGTYPE) {
+ disable_irq_nosync(irq);
+ scr |= SCSCR_RDRQE;
+ } else {
+ disable_irq_nosync(s->irqs[SCIx_RXI_IRQ]);
+ scif_set_rtrg(port, 1);
+ scr |= SCSCR_RIE;
+ }
} else {
if (sci_dma_rx_submit(s, false) < 0)
goto handle_pio;
Cheers,
Biju
>
> > }
> > serial_port_out(port, SCSCR, scr);
> > /* Clear current interrupt */
>
> 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
