Hi Geert,
On Tue, Nov 9, 2021 at 7:50 AM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
>
> Hi Prabhakar,
>
> On Tue, Nov 9, 2021 at 1:34 AM Lad, Prabhakar
> <prabhakar.csengg@xxxxxxxxx> wrote:
> > On Mon, Nov 8, 2021 at 4:40 PM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
> > > On Wed, Nov 3, 2021 at 6:31 PM Lad Prabhakar
> > > <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx> wrote:
> > > > On RZ/G2L devices should be explicitly pulled out of reset for it
> > > > to work. This patch adds support to read the "resets" property and
> > > > performs deassert/assert when required.
> > > >
> > > > Also, propagate the error to the caller of sci_parse_dt() instead of
> > > > returning NULL in case of failure.
> > > >
> > > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> > > > Reviewed-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > >
> > > Thanks for your patch!
> > >
> > > > ---
> > > > Hi Geert,
> > > > For handling the resets I was in dual mind whether to perform
> > > > reset based on compatible strings or soc-id, let me know your
> > > > thoughts. Currently no SoC's use "renesas,sci" so using the same
> > > > for performing the reset operation for SCI.
> > >
> > > We do, on H8/300.
> > >
> > Missed that.
> >
> > > > --- a/drivers/tty/serial/sh-sci.c
> > > > +++ b/drivers/tty/serial/sh-sci.c
> > > > @@ -3203,23 +3204,58 @@ static const struct of_device_id of_sci_match[] = {
> > > > };
> > > > MODULE_DEVICE_TABLE(of, of_sci_match);
> > > >
> > > > +static void sci_reset_control_assert(void *data)
> > > > +{
> > > > + reset_control_assert(data);
> > > > +}
> > > > +
> > > > static struct plat_sci_port *sci_parse_dt(struct platform_device *pdev,
> > > > unsigned int *dev_id)
> > > > {
> > > > struct device_node *np = pdev->dev.of_node;
> > > > + const struct of_device_id *of_id;
> > > > struct plat_sci_port *p;
> > > > struct sci_port *sp;
> > > > const void *data;
> > > > int id;
> > > >
> > > > if (!IS_ENABLED(CONFIG_OF) || !np)
> > > > - return NULL;
> > > > + return ERR_PTR(-EINVAL);
> > > > +
> > > > + of_id = of_match_device(of_sci_match, &pdev->dev);
> > > > + if (!of_id)
> > > > + return ERR_PTR(-EINVAL);
> > > >
> > > > - data = of_device_get_match_data(&pdev->dev);
> > > > + if (!strcmp(of_id->compatible, "renesas,scif-r9a07g044") ||
> > > > + !strcmp(of_id->compatible, "renesas,sci")) {
> > >
> > > This will match on H8/300, too, which doesn't have resets.
> > > Please match against "renesas,sci-r9a07g044" instead.
> > >
> > > Please don't use explicit strcmp() calls here, but add a flag to
> > > of_sci_match[].data.
> > >
> > Agreed, does the below hunk look good for handling the reset?
> >
> > -#define SCI_OF_DATA(type, regtype) (void *)((type) << 16 | (regtype))
> > +#define SCIx_RESET BIT(31)
> > +#define SCI_OF_DATA(type, regtype, reset) (void *)(reset |
> > (type) << 16 | (regtype))
> > #define SCI_OF_TYPE(data) ((unsigned long)(data) >> 16)
> > #define SCI_OF_REGTYPE(data) ((unsigned long)(data) & 0xffff)
> >
> > @@ -3169,7 +3170,11 @@ static const struct of_device_id of_sci_match[] = {
> > },
> > {
> > .compatible = "renesas,scif-r9a07g044",
> > - .data = SCI_OF_DATA(PORT_SCIF, SCIx_RZ_SCIFA_REGTYPE),
> > + .data = SCI_OF_DATA(PORT_SCIF, SCIx_RZ_SCIFA_REGTYPE,
> > SCIx_RESET),
> > + },
> > + {
> > + .compatible = "renesas,sci-r9a07g044",
> > + .data = SCI_OF_DATA(PORT_SCI, SCIx_SCI_REGTYPE, SCIx_RESET),
> > },
>
> That's what I had in mind.
>
> But upon second thought, it might be better to just drop the check,
> and obtain an optional reset instead?
Agreed, will do that.
> After all the reset requirement is not a feature of this specific
> SCI(F) variant, but an SoC integration feature. And deasserting
> the reset on other SoCs that have a reset should be fine.
>
Indeed.
Cheers,
Prabhakar
> 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
