在 2026-02-25三的 08:47 +0100，Thomas Zimmermann写道： > > > Am 25.02.26 um 08:38 schrieb Icenowy Zheng: > > 在 2026-02-25三的 08:26 +0100，Thomas Zimmermann写道： > > > Hi, > > > > > > Am 25.02.26 um 07:13 schrieb Icenowy Zheng: > > > > The ioctl interfaces for dumb buffers currently only properly > > > > support > > > > linear buffers. > > > > > > > > Mention this in the documentation snippet of dumb-buffers > > > > source > > > > code, > > > > which is referenced by drm-kms.rst and will end up in the built > > > > kernel > > > > documentation. > > > > > > > > Also mention the existence of current drivers abusing dumb > > > > buffers > > > > for > > > > AFBC to reduce confusion about this. > > > > > > > > Signed-off-by: Icenowy Zheng <[email protected]> > > > > --- > > > > drivers/gpu/drm/drm_dumb_buffers.c | 7 ++++++- > > > We documented the meaning of the color bits and the behavior of > > > the > > > dumb-buffer interface at [1]. If anything is missing, it should > > > be > > > added > > > there. > > Yes, I saw this piece of document; however it's part of the > > interface > > document instead of a concept document, and the whole existence of > > the > > What is a concept document?
Well I am patching this document snippet because it becomes part of the document at [1] (by being referenced in the .rst file). [1] https://docs.kernel.org/gpu/drm-kms.html#dumb-buffer-objects > > > document snippet I am changing can be considered a duplicate of the > > interface document. > > > > Thanks > > Icenowy > > > > > Best regards > > > Thomas > > > > > > [1] > > > https://elixir.bootlin.com/linux/v6.19/source/include/uapi/drm/drm_mode.h#L1200 > > > > > > > 1 file changed, 6 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/drivers/gpu/drm/drm_dumb_buffers.c > > > > b/drivers/gpu/drm/drm_dumb_buffers.c > > > > index e2b62e5fb891b..06f74460adf62 100644 > > > > --- a/drivers/gpu/drm/drm_dumb_buffers.c > > > > +++ b/drivers/gpu/drm/drm_dumb_buffers.c > > > > @@ -57,7 +57,12 @@ > > > > * > > > > * Note that dumb objects may not be used for gpu > > > > acceleration, > > > > as has been > > > > * attempted on some ARM embedded platforms. Such drivers > > > > really > > > > must have > > > > - * a hardware-specific ioctl to allocate suitable buffer > > > > objects. > > > > + * a hardware-specific ioctl to allocate suitable buffer > > > > objects. > > > > They are > > > > + * also currently meant for only linear buffers, and using > > > > them > > > > with any > > > > + * modifier other than DRM_FORMAT_MOD_LINEAR is undefined > > > > behavior. There > > > > + * exist some KMS drivers abusing dumb objects for AFBC > > > > framebuffers, but this > > > > + * behavior is discouraged, only exists as a hack now and > > > > shouldn't be > > > > + * replicated. > > > > */ > > > > > > > > static int drm_mode_align_dumb(struct drm_mode_create_dumb > > > > *args,
