[PATCH] drm: Return -ENOTSUPP in drm_setclientcap() when driver do not support KMS

[Chris Wilson]

Quoting José Roberto de Souza (2018-09-13 23:13:41)
> All DRM_CLIENT capabilities are tied to KMS support, so returning
> -ENOTSUPP when KMS is not supported.

The posix errno is ENOTSUP (ENOTSUPP is internal). Now since we have no
ENOTSUP in the uapi, I've switched to using EOPNOTSUP as that is
documented to have the same value as ENOTSUP under Linux. (At least
until somebody decided to make ENOTSUP unique.)

> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
> ---
>  drivers/gpu/drm/drm_ioctl.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
> index 6b4a633b4240..842423fe9762 100644
> --- a/drivers/gpu/drm/drm_ioctl.c
> +++ b/drivers/gpu/drm/drm_ioctl.c
> @@ -306,6 +306,9 @@ drm_setclientcap(struct drm_device *dev, void *data, struct drm_file *file_priv)
>  {
>         struct drm_set_client_cap *req = data;
>  
> +       if (!drm_core_check_feature(dev, DRIVER_MODESET))
> +               return -ENOTSUPP;

The wider question though is client cap restricted to modesetting
capabilities? Or should each case include a check like
DRM_CLIENT_CAP_ATOMIC.
-Chris