[PATCHv3 04/30] drm/omap: decrease min width & height

[Laurent Pinchart]

Hi Tomi,

On Wednesday 29 Mar 2017 11:26:45 Tomi Valkeinen wrote:
> On 29/03/17 11:24, Laurent Pinchart wrote:
> > On Wednesday 29 Mar 2017 11:23:00 Tomi Valkeinen wrote:
> >> On 29/03/17 11:13, Laurent Pinchart wrote:
> >>> On Tuesday 28 Mar 2017 16:07:50 Tomi Valkeinen wrote:
> >>>> mode_config's min_width and min_height are both set to 32, which is
> >>>> overly restrictive.
> >>>> 
> >>>> The real limits depend on whether we're configuring a crtc or a plane,
> >>>> but a limit of 8x2 is safe for both cases.
> >>> 
> >>> Strictly speaking it's planes in all cases, you could talk about primary
> >>> or overlay planes instead. Apart from that,
> >> 
> >> Hmm, well, on the HW they are different. We have CRTC limits, and we
> >> have plane limits.
> >> 
> >> In our HW, I think we can have 1x1 planes (at least with RGB). But CRTC
> >> minimum depends on the display used. In some cases CRTC minimum is 1x1,
> >> but usually it's 8x1 I think.
> >> 
> >> And talking about primary or overlay planes is so legacy... With atomic,
> >> we just have planes! =)
> > 
> > CRTCs and planes are KMS concepts, at the hardware level we have
> > background and overlay planes, don't we ?
> 
> No, on the HW level we have... I don't know what's the proper name, but
> whatever matches the CRTC. The dss driver calls it overlay manager, but
> that's a silly name too. It's the video timing generator, plus overlay
> composition. It does have a default background color, though.
> 
> And then we have overlays, i.e. planes.
> 
> You can have the CRTC enabled without any planes. Then you'll see the
> background color. If you have planes, they can be smaller than the CRTC.

The mode setting min/max width and height are used by the core when creating a 
framebuffer to validate its size. It's thus only related to planes, not to the 
CRTC.

-- 
Regards,

Laurent Pinchart