Hi Laurent.
On Tue, May 28, 2019 at 07:50:52PM +0300, Laurent Pinchart wrote:
> Hi Sam,
>
> On Tue, May 28, 2019 at 06:42:13PM +0200, Sam Ravnborg wrote:
> > On Tue, May 28, 2019 at 05:12:31PM +0300, Laurent Pinchart wrote:
> > > In dual-link LVDS mode, the LVDS1 encoder is used as a companion for
> > > LVDS0, and both encoders transmit data from DU0. The LVDS1 output of DU1
> > > can't be used in that case, don't create an encoder and connector for
> > > it.
> > >
> > > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
> > > Reviewed-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
> > > Tested-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
> > > ---
> > > Changess since v2:
> > >
> > > - Remove unneeded bridge NULL check
> > > ---
> > > drivers/gpu/drm/rcar-du/rcar_du_encoder.c | 12 ++++++++++++
> > > drivers/gpu/drm/rcar-du/rcar_du_kms.c | 2 +-
> > > 2 files changed, 13 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/rcar-du/rcar_du_encoder.c b/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
> > > index 6c91753af7bc..0f00bdfe2366 100644
> > > --- a/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
> > > +++ b/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
> > > @@ -16,6 +16,7 @@
> > > #include "rcar_du_drv.h"
> > > #include "rcar_du_encoder.h"
> > > #include "rcar_du_kms.h"
> > > +#include "rcar_lvds.h"
> > >
> > > /* -----------------------------------------------------------------------------
> > > * Encoder
> > > @@ -97,6 +98,17 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
> > > }
> > > }
> > >
> > > + /*
> > > + * On Gen3 skip the LVDS1 output if the LVDS1 encoder is used as a
> > > + * companion for LVDS0 in dual-link mode.
> > > + */
> > > + if (rcdu->info->gen >= 3 && output == RCAR_DU_OUTPUT_LVDS1) {
> >
> > Both subject and comment above says "On Gen3", but the code looks like
> > it implements "On Gen3 or newer" - due to use of ">=".
> > Looks wrong to me.
>
> Gen3 is the newest generation :-) We thus use >= through the DU and LVDS
> drivers to prepare for support of Gen4, just in case.
OK, but I guess we agree that the comment needs a small update them.
Actually I implicitly reads that it is only from Gen3 onwards that the
LVDS1 encoder can be used as a companion.
My initial understanding reading the comment was that this implmented a
workaround for Gen3 - but it is a workarounf for missing features in
older than Gen3.
So, assuming this is correct, when trying to specify a companion on
older then Gen3 should result in some kind of error/warning?
(Maybe it does).
Sam
