Hi Tomi, Thank you for the patch. On Fri, Dec 06, 2024 at 11:32:35AM +0200, Tomi Valkeinen wrote: > From: Tomi Valkeinen <tomi.valkeinen+renesas@xxxxxxxxxxxxxxxx> > > Currently the driver always writes DPTSR when setting up the hardware. > However, writing the register is only meaningful when the second source > for a plane is used, and the register is not even documented for SoCs > that do not have the second source. I've confirmed that for all the models currently supported by the DU driver. > So move the write behind a condition. > > Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas@xxxxxxxxxxxxxxxx> Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx> I will test the series on an M3N board. > --- > drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c | 20 +++++++++++++++----- > 1 file changed, 15 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c b/drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c > index 2ccd2581f544..1ec806c8e013 100644 > --- a/drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c > +++ b/drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c > @@ -185,11 +185,21 @@ 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); > + /* > + * DPTSR is used to select the source for the planes of a group. The > + * first source is chosen by writing 0 to the respective bits, and this > + * is always the default value of the register. In other words, writing > + * DPTSR is only needed if the SoC supports choosing the second source. > + * > + * The SoCs documentations seems to confirm this, as the DPTSR register > + * is not documented if only the first source exists on that SoC. > + */ > + if (rgrp->channels_mask & BIT(1)) { > + mutex_lock(&rgrp->lock); > + rcar_du_group_write(rgrp, DPTSR, (rgrp->dptsr_planes << 16) | > + rgrp->dptsr_planes); > + mutex_unlock(&rgrp->lock); > + } > } > > /* > -- Regards, Laurent Pinchart