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7 Jul 2021 05:59:58 +0530 From: Ramalingam C To: Matthew Auld Message-ID: <20210707002958.GA26377@intel.com> References: <20210705135310.1502437-1-matthew.auld@intel.com> <20210705135310.1502437-2-matthew.auld@intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210705135310.1502437-2-matthew.auld@intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Subject: Re: [Intel-gfx] [PATCH v3 2/5] drm/i915/uapi: convert drm_i915_gem_caching to kernel doc X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Thomas =?utf-8?Q?Hellstr=C3=B6m?= , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, Kenneth Graunke , Daniel Vetter Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" 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SElOR19ESVNQTEFZCQkyCj4gIAlfX3UzMiBjYWNoaW5nOwo+ICB9Owo+ICAKPiAtLSAKPiAyLjI2 LjMKPiAKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KSW50 ZWwtZ2Z4IG1haWxpbmcgbGlzdApJbnRlbC1nZnhAbGlzdHMuZnJlZWRlc2t0b3Aub3JnCmh0dHBz Oi8vbGlzdHMuZnJlZWRlc2t0b3Aub3JnL21haWxtYW4vbGlzdGluZm8vaW50ZWwtZ2Z4Cg== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B3A4FC07E9B for ; Wed, 7 Jul 2021 00:28:34 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher 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ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Jul 2021 17:28:22 -0700 X-IronPort-AV: E=Sophos;i="5.83,330,1616482800"; d="scan'208";a="481771723" Received: from ramaling-i9x.iind.intel.com (HELO intel.com) ([10.99.66.205]) by fmsmga004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Jul 2021 17:28:19 -0700 Date: Wed, 7 Jul 2021 05:59:58 +0530 From: Ramalingam C To: Matthew Auld Subject: Re: [PATCH v3 2/5] drm/i915/uapi: convert drm_i915_gem_caching to kernel doc Message-ID: <20210707002958.GA26377@intel.com> References: <20210705135310.1502437-1-matthew.auld@intel.com> <20210705135310.1502437-2-matthew.auld@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210705135310.1502437-2-matthew.auld@intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Thomas =?utf-8?Q?Hellstr=C3=B6m?= , Jason Ekstrand , Tvrtko Ursulin , Jordan Justen , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, Kenneth Graunke , Daniel Vetter Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 2021-07-05 at 14:53:07 +0100, Matthew Auld wrote: > Convert all the drm_i915_gem_caching bits to proper kernel doc. > > Suggested-by: Daniel Vetter > Signed-off-by: Matthew Auld LGTM. Reviewed-by: Ramalingam C > Cc: Thomas Hellström > Cc: Maarten Lankhorst > Cc: Tvrtko Ursulin > Cc: Jordan Justen > Cc: Kenneth Graunke > Cc: Jason Ekstrand > Cc: Daniel Vetter > Cc: Ramalingam C > --- > include/uapi/drm/i915_drm.h | 70 +++++++++++++++++++++++-------------- > 1 file changed, 43 insertions(+), 27 deletions(-) > > diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h > index 2f70c48567c0..d13c6c5fad04 100644 > --- a/include/uapi/drm/i915_drm.h > +++ b/include/uapi/drm/i915_drm.h > @@ -1363,43 +1363,59 @@ struct drm_i915_gem_busy { > }; > > /** > - * I915_CACHING_NONE > + * struct drm_i915_gem_caching - Set or get the caching for given object > + * handle. > * > - * GPU access is not coherent with cpu caches. Default for machines without an > - * LLC. > - */ > -#define I915_CACHING_NONE 0 > -/** > - * I915_CACHING_CACHED > + * Allow userspace to control the GTT caching bits for a given object when the > + * object is later mapped through the ppGTT(or GGTT on older platforms lacking > + * ppGTT support, or if the object is used for scanout). Note that this might > + * require unbinding the object from the GTT first, if its current caching value > + * doesn't match. > * > - * GPU access is coherent with cpu caches and furthermore the data is cached in > - * last-level caches shared between cpu cores and the gpu GT. Default on > - * machines with HAS_LLC. > - */ > -#define I915_CACHING_CACHED 1 > -/** > - * I915_CACHING_DISPLAY > * > - * Special GPU caching mode which is coherent with the scanout engines. > - * Transparently falls back to I915_CACHING_NONE on platforms where no special > - * cache mode (like write-through or gfdt flushing) is available. The kernel > - * automatically sets this mode when using a buffer as a scanout target. > - * Userspace can manually set this mode to avoid a costly stall and clflush in > - * the hotpath of drawing the first frame. > */ > -#define I915_CACHING_DISPLAY 2 > - > struct drm_i915_gem_caching { > /** > - * Handle of the buffer to set/get the caching level of. */ > + * @handle: Handle of the buffer to set/get the caching level. > + */ > __u32 handle; > > /** > - * Cacheing level to apply or return value > + * @caching: The GTT caching level to apply or possible return value. > + * > + * The supported @caching values: > * > - * bits0-15 are for generic caching control (i.e. the above defined > - * values). bits16-31 are reserved for platform-specific variations > - * (e.g. l3$ caching on gen7). */ > + * I915_CACHING_NONE: > + * > + * GPU access is not coherent with CPU caches. Default for machines > + * without an LLC. This means we need to manually clflush, if we want > + * GPU access to be coherent. > + * > + * I915_CACHING_CACHED: > + * > + * GPU access is coherent with CPU caches and furthermore the data is > + * cached in last-level caches shared between CPU cores and the GPU GT. > + * Default on machines with HAS_LLC. In general the fast shared > + * last-level cache(HAS_LLC) is considered much faster then platforms > + * which only support snooping(HAS_SNOOP), hence by default > + * > + * I915_CACHING_DISPLAY: > + * > + * Special GPU caching mode which is coherent with the scanout engines. > + * Transparently falls back to I915_CACHING_NONE on platforms where no > + * special cache mode (like write-through or gfdt flushing) is > + * available. The kernel automatically sets this mode when using a > + * buffer as a scanout target. Userspace can manually set this mode to > + * avoid a costly stall and clflush in the hotpath of drawing the first > + * frame. > + * > + * Side note: On gen8+ this no longer does much since we lost the GGTT > + * caching bits. Although setting this is harmless, since it still > + * effectively falls back to I915_CACHING_NONE. > + */ > +#define I915_CACHING_NONE 0 > +#define I915_CACHING_CACHED 1 > +#define I915_CACHING_DISPLAY 2 > __u32 caching; > }; > > -- > 2.26.3 >