On Wed,  9 Jun 2021 20:00:38 -0300
Leandro Ribeiro <leandro.ribeiro@collabora.com> wrote:

> In this patch we add a section to document what userspace should do to
> find out the CRTC index. This is important as they may be many places in
> the documentation that need this, so it's better to just point to this
> section and avoid repetition.
> 
> Signed-off-by: Leandro Ribeiro <leandro.ribeiro@collabora.com>
> ---
>  Documentation/gpu/drm-uapi.rst    | 13 +++++++++++++
>  drivers/gpu/drm/drm_debugfs_crc.c |  8 ++++----
>  include/uapi/drm/drm.h            |  4 ++--
>  3 files changed, 19 insertions(+), 6 deletions(-)
> 
> diff --git a/Documentation/gpu/drm-uapi.rst b/Documentation/gpu/drm-uapi.rst
> index 04bdc7a91d53..7e51dd40bf6e 100644
> --- a/Documentation/gpu/drm-uapi.rst
> +++ b/Documentation/gpu/drm-uapi.rst
> @@ -457,6 +457,19 @@ Userspace API Structures
>  .. kernel-doc:: include/uapi/drm/drm_mode.h
>     :doc: overview
> 
> +.. _crtc_index:
> +
> +CRTC index
> +----------
> +
> +CRTC's have both an object ID and an index, and they are not the same thing.
> +The index is used in cases where a densely packed identifier for a CRTC is
> +needed, for instance a bitmask of CRTC's. The member possible_crtcs of struct
> +drm_mode_get_plane is an example.
> +
> +DRM_IOCTL_MODE_GETRESOURCES populates a structure with an array of CRTC ID's,
> +and the CRTC index is its position in this array.
> +
>  .. kernel-doc:: include/uapi/drm/drm.h
>     :internal:
> 
> diff --git a/drivers/gpu/drm/drm_debugfs_crc.c b/drivers/gpu/drm/drm_debugfs_crc.c
> index 3dd70d813f69..bbc3bc4ba844 100644
> --- a/drivers/gpu/drm/drm_debugfs_crc.c
> +++ b/drivers/gpu/drm/drm_debugfs_crc.c
> @@ -46,10 +46,10 @@
>   * it reached a given hardware component (a CRC sampling "source").
>   *
>   * Userspace can control generation of CRCs in a given CRTC by writing to the
> - * file dri/0/crtc-N/crc/control in debugfs, with N being the index of the CRTC.
> - * Accepted values are source names (which are driver-specific) and the "auto"
> - * keyword, which will let the driver select a default source of frame CRCs
> - * for this CRTC.
> + * file dri/0/crtc-N/crc/control in debugfs, with N being the :ref:`index of
> + * the CRTC<crtc_index>`. Accepted values are source names (which are
> + * driver-specific) and the "auto" keyword, which will let the driver select a
> + * default source of frame CRCs for this CRTC.
>   *
>   * Once frame CRC generation is enabled, userspace can capture them by reading
>   * the dri/0/crtc-N/crc/data file. Each line in that file contains the frame
> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
> index 67b94bc3c885..bbf4e76daa55 100644
> --- a/include/uapi/drm/drm.h
> +++ b/include/uapi/drm/drm.h
> @@ -635,8 +635,8 @@ struct drm_gem_open {
>  /**
>   * DRM_CAP_VBLANK_HIGH_CRTC
>   *
> - * If set to 1, the kernel supports specifying a CRTC index in the high bits of
> - * &drm_wait_vblank_request.type.
> + * If set to 1, the kernel supports specifying a :ref:`CRTC index<crtc_index>`
> + * in the high bits of &drm_wait_vblank_request.type.
>   *
>   * Starting kernel version 2.6.39, this capability is always set to 1.
>   */
> --
> 2.31.1
> 

Hi,

with the caveat that I didn't actually build the docs and see how they
look:

Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.com>


Thanks,
pq