From patchwork Tue Aug 10 12:34:08 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 12428815 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=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 176E8C4338F for ; Tue, 10 Aug 2021 12:34:30 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B7B5560462 for ; Tue, 10 Aug 2021 12:34:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org B7B5560462 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id F291889E39; Tue, 10 Aug 2021 12:34:21 +0000 (UTC) Received: from mail-wm1-x330.google.com (mail-wm1-x330.google.com [IPv6:2a00:1450:4864:20::330]) by gabe.freedesktop.org (Postfix) with ESMTPS id C03E989C63 for ; Tue, 10 Aug 2021 12:34:20 +0000 (UTC) Received: by mail-wm1-x330.google.com with SMTP id l34-20020a05600c1d22b02902573c214807so1846301wms.2 for ; Tue, 10 Aug 2021 05:34:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=HYk+3h+xsdxcmcK8ofz+YfFtNmjj8XuZmW3LS1ids7A=; b=Vdra8eL5wGATIKBqTqSyrH7H3+KuqvR2V1Ebl0DUFXqVYNccD6cwKfFZ7iSEtdR36Y DI2qLIQPKrZy2lquWNqPf13sFawhR+3bL1d5H1RhVvew/QwHEqMT322AgclBYHu/aVhO KGzaj+UT3Ctv6g3dSpUaqjUFjvukUYBRz+PU0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=HYk+3h+xsdxcmcK8ofz+YfFtNmjj8XuZmW3LS1ids7A=; b=gOvMXK74Wud6LuglCWz2Iv3zvMcJ0tG5JXKJWSmLtzBMpNzcMGvpwpt2AbA8VvdkJn INUAANvFcjzOll8pzfUK8C2YtsU0jhaZy6VYC2tQ8Deo15zbOJDkk7L4eeupEaVgAiqu lJ40lEA2F8eXsZcZkFJOZxSSeG2fzXRakIHPj9JWcmtBLZN4zuVidXXjEGwABpv0b28x pMgiwO4uDV404FWmW8P7n8f8xIj5ASDpaKRKr6cIko6L0fCOzbt6TxTD55aPRL3Ay7C/ Q4Z7GEI+FGT3DehmmTPcL+KfRllfjaPicwkyld3ouRLGAaPMZJSIKjfcQIE6En2UIjUE g0uA== X-Gm-Message-State: AOAM533+LEWZcvlATjiEe39TLnXSg27R5Y9f+7JicHvO/A7uliZbjz2E iuWPOacSbehNDXdlSw0y/Xz9sg== X-Google-Smtp-Source: ABdhPJwXMuqxcxS8QV8jK36KErcoIsEcDbc013LYNCPNi3AWYphKakRC5EH7poHDvNHGQHhKXvRmTw== X-Received: by 2002:a1c:9884:: with SMTP id a126mr4575256wme.153.1628598859264; Tue, 10 Aug 2021 05:34:19 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id n186sm3142048wme.40.2021.08.10.05.34.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Aug 2021 05:34:18 -0700 (PDT) From: Daniel Vetter To: DRI Development Cc: Intel Graphics Development , Daniel Vetter , Stephen Rothwell , Matthew Auld , Daniel Vetter Date: Tue, 10 Aug 2021 14:34:08 +0200 Message-Id: <20210810123408.1870870-1-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.32.0 MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH] drm/doc/rfc: drop lmem uapi section 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: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" We still have quite a bit more work to do with overall reworking of the ttm-based dg1 code, but the uapi stuff is now finalized with the latest pull. So remove that. This also fixes kerneldoc build warnings because we've included the same headers in two places, resulting in sphinx complaining about duplicated symbols. This regression has been created when we moved the uapi definitions to the real include/uapi/ folder in 727ecd99a4c9 ("drm/doc/rfc: drop the i915_gem_lmem.h header") Reported-by: Stephen Rothwell Cc: Stephen Rothwell Fixes: 727ecd99a4c9 ("drm/doc/rfc: drop the i915_gem_lmem.h header") Cc: Matthew Auld Signed-off-by: Daniel Vetter Acked-by: Jason Ekstrand --- Documentation/gpu/rfc/i915_gem_lmem.rst | 107 ------------------------ 1 file changed, 107 deletions(-) diff --git a/Documentation/gpu/rfc/i915_gem_lmem.rst b/Documentation/gpu/rfc/i915_gem_lmem.rst index 675ba8620d66..91be041e68cc 100644 --- a/Documentation/gpu/rfc/i915_gem_lmem.rst +++ b/Documentation/gpu/rfc/i915_gem_lmem.rst @@ -22,110 +22,3 @@ real, with all the uAPI bits is: * SET/GET ioctl caching(see `I915 SET/GET CACHING`_) * Send RFC(with mesa-dev on cc) for final sign off on the uAPI * Add pciid for DG1 and turn on uAPI for real - -New object placement and region query uAPI -========================================== -Starting from DG1 we need to give userspace the ability to allocate buffers from -device local-memory. Currently the driver supports gem_create, which can place -buffers in system memory via shmem, and the usual assortment of other -interfaces, like dumb buffers and userptr. - -To support this new capability, while also providing a uAPI which will work -beyond just DG1, we propose to offer three new bits of uAPI: - -DRM_I915_QUERY_MEMORY_REGIONS ------------------------------ -New query ID which allows userspace to discover the list of supported memory -regions(like system-memory and local-memory) for a given device. We identify -each region with a class and instance pair, which should be unique. The class -here would be DEVICE or SYSTEM, and the instance would be zero, on platforms -like DG1. - -Side note: The class/instance design is borrowed from our existing engine uAPI, -where we describe every physical engine in terms of its class, and the -particular instance, since we can have more than one per class. - -In the future we also want to expose more information which can further -describe the capabilities of a region. - -.. kernel-doc:: include/uapi/drm/i915_drm.h - :functions: drm_i915_gem_memory_class drm_i915_gem_memory_class_instance drm_i915_memory_region_info drm_i915_query_memory_regions - -GEM_CREATE_EXT --------------- -New ioctl which is basically just gem_create but now allows userspace to provide -a chain of possible extensions. Note that if we don't provide any extensions and -set flags=0 then we get the exact same behaviour as gem_create. - -Side note: We also need to support PXP[1] in the near future, which is also -applicable to integrated platforms, and adds its own gem_create_ext extension, -which basically lets userspace mark a buffer as "protected". - -.. kernel-doc:: include/uapi/drm/i915_drm.h - :functions: drm_i915_gem_create_ext - -I915_GEM_CREATE_EXT_MEMORY_REGIONS ----------------------------------- -Implemented as an extension for gem_create_ext, we would now allow userspace to -optionally provide an immutable list of preferred placements at creation time, -in priority order, for a given buffer object. For the placements we expect -them each to use the class/instance encoding, as per the output of the regions -query. Having the list in priority order will be useful in the future when -placing an object, say during eviction. - -.. kernel-doc:: include/uapi/drm/i915_drm.h - :functions: drm_i915_gem_create_ext_memory_regions - -One fair criticism here is that this seems a little over-engineered[2]. If we -just consider DG1 then yes, a simple gem_create.flags or something is totally -all that's needed to tell the kernel to allocate the buffer in local-memory or -whatever. However looking to the future we need uAPI which can also support -upcoming Xe HP multi-tile architecture in a sane way, where there can be -multiple local-memory instances for a given device, and so using both class and -instance in our uAPI to describe regions is desirable, although specifically -for DG1 it's uninteresting, since we only have a single local-memory instance. - -Existing uAPI issues -==================== -Some potential issues we still need to resolve. - -I915 MMAP ---------- -In i915 there are multiple ways to MMAP GEM object, including mapping the same -object using different mapping types(WC vs WB), i.e multiple active mmaps per -object. TTM expects one MMAP at most for the lifetime of the object. If it -turns out that we have to backpedal here, there might be some potential -userspace fallout. - -I915 SET/GET CACHING --------------------- -In i915 we have set/get_caching ioctl. TTM doesn't let us to change this, but -DG1 doesn't support non-snooped pcie transactions, so we can just always -allocate as WB for smem-only buffers. If/when our hw gains support for -non-snooped pcie transactions then we must fix this mode at allocation time as -a new GEM extension. - -This is related to the mmap problem, because in general (meaning, when we're -not running on intel cpus) the cpu mmap must not, ever, be inconsistent with -allocation mode. - -Possible idea is to let the kernel picks the mmap mode for userspace from the -following table: - -smem-only: WB. Userspace does not need to call clflush. - -smem+lmem: We only ever allow a single mode, so simply allocate this as uncached -memory, and always give userspace a WC mapping. GPU still does snooped access -here(assuming we can't turn it off like on DG1), which is a bit inefficient. - -lmem only: always WC - -This means on discrete you only get a single mmap mode, all others must be -rejected. That's probably going to be a new default mode or something like -that. - -Links -===== -[1] https://patchwork.freedesktop.org/series/86798/ - -[2] https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5599#note_553791