[PATCH v2] drm: Return -ENOTSUPP when called for KMS cap with a non-KMS driver

[Alex Deucher]

On Thu, Dec 1, 2016 at 2:37 AM, Michel Dänzer <michel at daenzer.net> wrote:
> From: Michel Dänzer <michel.daenzer at amd.com>
>
> This is an attempt to make the previous fix a bit more robust going
> forward.
>
> v2:
> * Only allow DRM_CAP_TIMESTAMP_MONOTONIC with UMS drivers (Daniel
>   Vetter, Alex Deucher)
> * Different logic to keep DRM_CAP_TIMESTAMP_MONOTONIC separate from
>   the other caps (Daniel Vetter)
>
> Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>

Reviewed-by: Alex Deucher <alexander.deucher at amd.com>

> ---
>  drivers/gpu/drm/drm_ioctl.c | 24 +++++++++++++++---------
>  1 file changed, 15 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
> index 71c3473..706d5aa 100644
> --- a/drivers/gpu/drm/drm_ioctl.c
> +++ b/drivers/gpu/drm/drm_ioctl.c
> @@ -229,6 +229,17 @@ static int drm_getcap(struct drm_device *dev, void *data, struct drm_file *file_
>         struct drm_crtc *crtc;
>
>         req->value = 0;
> +
> +       /* Only one cap makes sense with a UMS driver: */
> +       if (req->capability == DRM_CAP_TIMESTAMP_MONOTONIC) {
> +               req->value = drm_timestamp_monotonic;
> +               return 0;
> +       }
> +
> +       /* Other caps only work with KMS drivers */
> +       if (!drm_core_check_feature(dev, DRIVER_MODESET))
> +               return -ENOTSUPP;
> +
>         switch (req->capability) {
>         case DRM_CAP_DUMB_BUFFER:
>                 if (dev->driver->dumb_create)
> @@ -247,19 +258,14 @@ static int drm_getcap(struct drm_device *dev, void *data, struct drm_file *file_
>                 req->value |= dev->driver->prime_fd_to_handle ? DRM_PRIME_CAP_IMPORT : 0;
>                 req->value |= dev->driver->prime_handle_to_fd ? DRM_PRIME_CAP_EXPORT : 0;
>                 break;
> -       case DRM_CAP_TIMESTAMP_MONOTONIC:
> -               req->value = drm_timestamp_monotonic;
> -               break;
>         case DRM_CAP_ASYNC_PAGE_FLIP:
>                 req->value = dev->mode_config.async_page_flip;
>                 break;
>         case DRM_CAP_PAGE_FLIP_TARGET:
> -               if (drm_core_check_feature(dev, DRIVER_MODESET)) {
> -                       req->value = 1;
> -                       drm_for_each_crtc(crtc, dev) {
> -                               if (!crtc->funcs->page_flip_target)
> -                                       req->value = 0;
> -                       }
> +               req->value = 1;
> +               drm_for_each_crtc(crtc, dev) {
> +                       if (!crtc->funcs->page_flip_target)
> +                               req->value = 0;
>                 }
>                 break;
>         case DRM_CAP_CURSOR_WIDTH:
> --
> 2.10.2
>
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