[Intel-gfx] [PATCH 1/1] drm/i915: Avoid initializing framebuffer without pipes

[Chris Wilson]

Quoting Mika Kuoppala (2018-10-19 13:30:37)
> If we try to initialize a framebuffer without pipes, we get oops
> as we fail to get valid crtc for a PIPE A, on trying to find
> pitch limits. This is easily demonstrated by trying to init
> framebuffer with displays disabled by 'i915.disable_display=1'
> kernel cmdline.
> 
> Fix this by omitting framebuffer init early if there are no pipes.
> 
> Testcase: igt/kms_addfb_basic
> Cc: Ville Syrjala <ville.syrjala at linux.intel.com>
> Signed-off-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>

To which Ville previously replied with the suggestion of preventing the
ioctl from even getting this far, to whit

if (!INTEL_INFO(dev_priv)->num_pipes)
	i915->drm.driver_features &= ~DRIVER_MODESET

See https://patchwork.freedesktop.org/series/51000/
-Chris