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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E374FC433FE for ; Mon, 31 Jan 2022 14:58:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349239AbiAaO6j (ORCPT ); Mon, 31 Jan 2022 09:58:39 -0500 Received: from mga03.intel.com ([134.134.136.65]:12947 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232149AbiAaO6d (ORCPT ); Mon, 31 Jan 2022 09:58:33 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1643641112; x=1675177112; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=BxH+tZ/fu2IEVr/ao5807gbpeXmiy9cIQ6HmY7vsj8A=; b=h/lKA8rwBqH9QijjbZk6acVqASFgEs+U/ue3KPsvQJZX/NYkeiV7mrG9 dr56FjyJNOlCLYo72N9hr6hvin821+YlsRFMZSPhDFTPcIRJjCjC53RtA AWWcKvBnleA5XlBYhmS8j/Ntc4RKP8EossvwD65GkRq4t6V/5VfUH8VXB Q46Kuyd9rZuMZNZyLwDh4TuaYLmJ1Nl0SI/HPO+mYt8DGDZ+kwmlFLraF 5iQGb6qSNFSK17lNxQ3zfvkveKhf/IaXrVU4B5V++xa/Ttchx9T3gqEah DUE9MRtPpo8mGFXXh+FKAKlqMpNbFOXdzMSoAVN6jtUdiOrTcVKMzxKFd w==; X-IronPort-AV: E=McAfee;i="6200,9189,10243"; a="247429261" X-IronPort-AV: E=Sophos;i="5.88,331,1635231600"; d="scan'208";a="247429261" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Jan 2022 06:58:31 -0800 X-IronPort-AV: E=Sophos;i="5.88,331,1635231600"; d="scan'208";a="626388374" Received: from yeidelbe-mobl1.ger.corp.intel.com (HELO [10.249.254.103]) ([10.249.254.103]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Jan 2022 06:58:29 -0800 Message-ID: <8ecf5706-84c2-2e30-9ee3-0f428ed95961@linux.intel.com> Date: Mon, 31 Jan 2022 15:58:26 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.3.0 Subject: Re: [Intel-gfx] [PATCH v5 1/5] drm/i915: add needs_compact_pt flag Content-Language: en-US To: Robert Beckett , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , David Airlie , Daniel Vetter Cc: intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Matthew Auld References: <20220125193530.3272386-1-bob.beckett@collabora.com> <20220125193530.3272386-2-bob.beckett@collabora.com> <6d0a57e7-daf7-6436-e806-7cc8794c2d50@shipmail.org> <19bf8290-9308-b5c6-eb73-4020fa81aa66@collabora.com> <094b3a2d-0829-c34c-3a3d-e9639095f469@collabora.com> From: =?UTF-8?Q?Thomas_Hellstr=c3=b6m?= In-Reply-To: <094b3a2d-0829-c34c-3a3d-e9639095f469@collabora.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/31/22 15:19, Robert Beckett wrote: > > > On 27/01/2022 09:37, Thomas Hellström (Intel) wrote: >> >> On 1/26/22 18:11, Robert Beckett wrote: >>> >>> >>> On 26/01/2022 13:49, Thomas Hellström (Intel) wrote: >>>> >>>> On 1/25/22 20:35, Robert Beckett wrote: >>>>> From: Ramalingam C >>>>> >>>>> Add a new platform flag, needs_compact_pt, to mark the requirement of >>>>> compact pt layout support for the ppGTT when using 64K GTT pages. >>>>> >>>>> With this flag has_64k_pages will only indicate requirement of 64K >>>>> GTT page sizes or larger for device local memory access. >>>>> >>>>> Suggested-by: Matthew Auld >>>>> Signed-off-by: Ramalingam C >>>>> Signed-off-by: Robert Beckett >>>>> --- >>>>>   drivers/gpu/drm/i915/i915_drv.h          | 10 +++++++--- >>>>>   drivers/gpu/drm/i915/i915_pci.c          |  2 ++ >>>>>   drivers/gpu/drm/i915/intel_device_info.h |  1 + >>>>>   3 files changed, 10 insertions(+), 3 deletions(-) >>>>> >>>>> diff --git a/drivers/gpu/drm/i915/i915_drv.h >>>>> b/drivers/gpu/drm/i915/i915_drv.h >>>>> index 44c1f98144b4..1258b7779705 100644 >>>>> --- a/drivers/gpu/drm/i915/i915_drv.h >>>>> +++ b/drivers/gpu/drm/i915/i915_drv.h >>>>> @@ -1512,12 +1512,16 @@ IS_SUBPLATFORM(const struct >>>>> drm_i915_private *i915, >>>>>   /* >>>>>    * Set this flag, when platform requires 64K GTT page sizes or >>>>> larger for >>>>> - * device local memory access. Also this flag implies that we >>>>> require or >>>>> - * at least support the compact PT layout for the ppGTT when >>>>> using the 64K >>>>> - * GTT pages. >>>> >>>> Why do we remove these comment lines? >>> Because HAS_64K_PAGES now means just 64K page, it no longer means >>> also requires compact pt. >>> This is to support other products that will have 64K but not have >>> the PDE non-sharing restriction in future. >>> >>> Those lines moved to the next change NEEDS_COMPACT_PT, which is now >>> separate. >> >> Yes, NEEDS_COMPACT_PT indicates that compact is *required* but does >> "HAS_64K_PAGES" still mean compact is supported? That information is >> lost. > Not any more. > I discussed the ambiguity of the original wording with mauld on irc. > We came to the conclusion that HAS_64K_PAGES should mean just that, > that the hw has support for 64K pages, and says nothing about > compact-pt at all. > > NEEDS_COMPACT_PT means that the hw has compact-pt support and the > driver is required to use it as it is a hw limitation. > > There will be other devices that can support compact-pt but do not > mandate its use. In this case, the current code would not use them, > but there is potential for some future opportunistic use of that in > the driver if desired (currently expected to include accelerated > move/clear). If any opportunistic use is added to the driver, a new > flag can be added along with the code that uses it to indicate > compact-pt availability that is not mandatory (HAS_COMPACT_PT most > likely), but as there is no code requiring it currently it should not > be added yet, and the comments left as this patch does. > Ok, Thanks for the clarification. Reviewed-by: Thomas Hellström >> >> /Thomas >> >>