Hi Stefan,
On Mi, 2019-08-14 at 13:03 +0200, Stefan Agner wrote:
> On 2019-08-14 12:48, Robert Chiras wrote:
> >
> > Add new optional property 'max-res', to limit the maximum supported
> > resolution by the MXSFB_DRM driver.
> I would also mention the reason why we need this.
>
> I guess this needs a vendor prefix as well (fsl,max-res). I also
> would
> like to have the ack of the device tree folks here.
Rob Herring also aked be about this, and I'll copy here the reply, with
explanations:
Indeed, this limitation is actually due to bandwidth limitation, but
the problem is that this limitation comes on i.MX8M (known as mScale
850D), where the memory bandwidth cannot support: GPU/VPU workload in
the same time with both DCSS driving 4k@60 and eLCDIF driving 1080p@60.
Since eLCDIF is a secondary display we though to add the posibility to
limit it's bandwidth by limiting the resolution.
If you say that more details are needed, I can add them in the
description.
>
> --
> Stefan
>
> >
> >
> > Signed-off-by: Robert Chiras <robert.chiras@xxxxxxx>
> > ---
> > Documentation/devicetree/bindings/display/mxsfb.txt | 6 ++++++
> > 1 file changed, 6 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/display/mxsfb.txt
> > b/Documentation/devicetree/bindings/display/mxsfb.txt
> > index 472e1ea..55e22ed 100644
> > --- a/Documentation/devicetree/bindings/display/mxsfb.txt
> > +++ b/Documentation/devicetree/bindings/display/mxsfb.txt
> > @@ -17,6 +17,12 @@ Required properties:
> > Required sub-nodes:
> > - port: The connection to an encoder chip.
> >
> > +Optional properties:
> > +- max-res: an array with a maximum of two integers, representing
> > the
> > + maximum supported resolution, in the form of
> > + <maxX>, <maxY>; if one of the item is <0>, the
> > default
> > + driver-defined maximum resolution for that axis is
> > used
> > +
> > Example:
> >
> > lcdif1: display-controller@2220000 {
Thanks,
Robert
