[Intel-gfx] [PATCH v2 5/5] drm/i915: Bump gen4+ fb size limits to 32kx32k

[Chris Wilson]

Quoting Ville Syrjälä (2018-09-19 17:59:51)
> On Thu, Sep 13, 2018 at 11:01:40PM +0300, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > With gtt remapping in place we can use arbitraily large framebuffers.
> > Let's bump the limits as high as we can (32k-1). Going beyond that
> > would require switching our s16.16 src coordinate representation to
> > something with more spare bits.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_display.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 346572cf734a..0ee6255cd040 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -15527,8 +15527,8 @@ int intel_modeset_init(struct drm_device *dev)
> >               dev->mode_config.max_width = 4096;
> >               dev->mode_config.max_height = 4096;
> >       } else {
> > -             dev->mode_config.max_width = 8192;
> > -             dev->mode_config.max_height = 8192;
> > +             dev->mode_config.max_width = 32767;
> > +             dev->mode_config.max_height = 32767;
> 
> It appears that neither Mesa nor glamor will check whether window system
> buffers exceed the capabilities of the 3D engine. So trying to use a >16k
> trips an assert when genxml tries to pack the surface_state.
> 
> So looks like we'll need to limit this to 16k for gen7+, and leave it
> at 8k for gen4+. If userspace gets smarter later on we could add a new
> client cap to expose higher limits.

At which point, the client can just ignore this field and just use
rejection criteria from addfb2 and/or setcrtc (or the atomic variant).

Or we can just keep this field as meaning the maximum size of a single
CRTC and just ignore it entirely in -modesetting for fb size as we do
elsewhere.
-Chris