[PATCH xserver] modesetting: Fix page flipping harder under DRI 3.2.

[Daniel Stone]

On 4 April 2018 at 02:49, Mario Kleiner <mario.kleiner.de at gmail.com> wrote:
> Non-atomic kms drivers like radeon-kms (or nouveau-kms with
> default setting of "atomic ioctl disabled") don't export
> any formats, so num_formats == 0.
>
> Some atomic drivers (nouveau-kms with boot param nouveau.atomic=1,
> or intel-kms on, e.g., Linux 4.13) expose num_formats == 0, or
> don't expose any modifiers, so num_modifiers == 0.
>
> Let the drmmode_is_format_supported() check pass in these cases
> to allow page flipping, as it works just fine.
>
> Tested on NV-96 for nouveau, HD-5770 for radeon, Intel Ivybridge
> with Linux 4.13 and drm-next to fix page flipping.

Reviewed-by: Daniel Stone <daniels at collabora.com>

Cheers,
Daniel