Hi Geert
On Thu, Jun 20, 2024 at 02:48:49PM GMT, Geert Uytterhoeven wrote:
> Hi Laurent, Jacopo,
>
> On Wed, Jun 19, 2024 at 9:46 PM Laurent Pinchart
> <laurent.pinchart@xxxxxxxxxxxxxxxx> wrote:
> > On Wed, Jun 19, 2024 at 12:22:18PM +0200, Jacopo Mondi wrote:
> > > Add support for R-Car R8A779H0 V4M which has similar characteristics
> > > as the already supported R-Car V4H R8A779G0, but with a single output
> > > channel.
> > >
> > > Signed-off-by: Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx>
>
> > > --- a/drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c
> > > +++ b/drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c
> > > @@ -185,11 +187,16 @@ static void rcar_du_group_setup(struct rcar_du_group *rgrp)
> > > dorcr |= DORCR_PG1T | DORCR_DK1S | DORCR_PG1D_DS1;
> > > rcar_du_group_write(rgrp, DORCR, dorcr);
> > >
> > > - /* Apply planes to CRTCs association. */
> > > - mutex_lock(&rgrp->lock);
> > > - rcar_du_group_write(rgrp, DPTSR, (rgrp->dptsr_planes << 16) |
> > > - rgrp->dptsr_planes);
> > > - mutex_unlock(&rgrp->lock);
> > > + /*
> > > + * Apply planes to CRTCs association, skip for V4M which has a single
> > > + * channel.
> >
> > " and doesn't implement the DPTSR register."
> >
> > I'm pretty sure writing it is still harmless, but...
> >
> > > + */
> > > + if (rcdu->info->gen < 4 || rgrp->num_crtcs > 1) {
>
> Looking at the R-Car Gen3 docs, this check seems to be wrong, and the
> lack of a check might have been an issue before?
Not sure I got from your comment what part is wrong.
Reading below it seems you're suggesting that writes to DPTSR should
be skipped for some Gen3 boards as well ?
>
> Seems like the register (per pair) is only present if the second CRTC
> of a CRTC pair is present, so R-Car V3M and V3H (single CRTC) do not
> have DPTSR at all, and M3-W (triple CRTC) does not have it on the
> second pair. M3-N does have both, as it lacks the first CRTC of
> second pair, but does have the second CRTC of the second pair.
>
/o\
So far however, all Gen3 SoCs you mentioned seem to work with DPTSR
being written and the BSP [1] only actually skips it for V4M.
What would you suggesting in this case ? Addressing gen3 as well ?
That's something that would require testing on all the above boards
thought.
Thanks
j
[1] https://github.com/renesas-rcar/linux-bsp/commit/f2fc3314dab2052240653c1a31ba3d7c7190038e#diff-8bce6f4032dc891042e2561163754f49723ac119ae63df2425cc3487b432ee1cR206
> > > + mutex_lock(&rgrp->lock);
> > > + rcar_du_group_write(rgrp, DPTSR, (rgrp->dptsr_planes << 16) |
> > > + rgrp->dptsr_planes);
> > > + mutex_unlock(&rgrp->lock);
> > > + }
> > > }
>
> 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
