[Intel-gfx] [PATCH] drm/i915: Remove fb pitch limit for no display

[Chris Wilson]

Quoting Ville Syrjälä (2018-09-13 13:26:48)
> On Thu, Sep 13, 2018 at 12:05:49PM +0100, Chris Wilson wrote:
> > Quoting Ville Syrjälä (2018-09-13 11:56:56)
> > > On Thu, Sep 13, 2018 at 11:39:23AM +0100, Chris Wilson wrote:
> > > > If there is not a display (and so no CRTCs) then there is no upper limit
> > > > to the framebuffer pitch imposed by the CRTC.
> > > 
> > > Should we still allow you to create framebuffers in that case?
> > 
> > Up to you, imho is that fb are just bo with a bit of description. I
> > didn't see much harm in creating an fb even if it was never going to be
> > attached to any pipe. I don't have a solid usecase, just feels like it
> > reduces the impact on the API.
> 
> To me it feels a bit like giving userspace false hope that they
> can actually do something with the fb later.
> 
> > 
> > Hmm, however if we
> >       if (num_pipes == 0) driver_features &= ~DRIVER_MODESET;
> > we will kill the unusable API at the ioctl boundary.
> 
> That seems a bit wrong. We'd really want to device_features for
> something like that. Not sure how many things we have in the driver
> struct that really ought to be under the device.

Hah, yes it is one level too deep. I think the current set of
driver_features is more or less device_features? That seems like an easy
job though -- though some may point out that this smells of midlayer ;)
-Chris