[PATCH v4 1/2] drm/doc: document how userspace should find out CRTC index

[Daniel Vetter]

On Thu, Jun 10, 2021 at 11:27:42AM +0300, Pekka Paalanen wrote:
> On Wed,  9 Jun 2021 20:00:38 -0300
> Leandro Ribeiro <leandro.ribeiro at 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 at 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 at collabora.com>

Pushed to drm-misc-next, thanks for the patch&review.
-Daniel

> 
> 
> Thanks,
> pq



-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch