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RCPT_COUNT_SEVEN(0.00)[7]; RCVD_VIA_SMTP_AUTH(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:url,suse.de:dkim,suse.de:mid,iscas.ac.cn:email,bootlin.com:url] X-Rspamd-Queue-Id: 9F5673F6B9 X-Spam-Flag: NO X-Spam-Score: -4.51 X-Spam-Level: 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 >>> --- >>>   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? > 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, -- -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)