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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 396B5C433FE for ; Wed, 12 Oct 2022 09:22:08 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 30C3510E06D; Wed, 12 Oct 2022 09:22:07 +0000 (UTC) Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by gabe.freedesktop.org (Postfix) with ESMTPS id 5AC1310E06D for ; Wed, 12 Oct 2022 09:22:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1665566524; x=1697102524; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=zMQUzBpHeysrPjPMs84o7X0uvkwZYYi/fV55+u4yK50=; b=ZJYqiWRfJN/RTwst5EwO/e+tlGcv53v6wJYEvWkTnXPEsjv7U++I6IEf W2OVzik2ELbQ/z9yjgJNVpLDPGke8gFH4qbTVdIkR0QokW0HtFmuxtnzl D5P9DRs2NPnz+UP8ADjSGcO0MQmTc04OcihX9PdomulrV3UBQP743jlpY qxssAjhgvyLgkygTg5++uyVRaR1u1bZZlBP3r9SXy2zfdilp1nGhRmB6O Q5kJwkGTYfQjUzaI9gdWxROLecI7v+kKeoeU5C1Uy7iRVY5W0IkBLScpI 8RaZOWTadu+E3WhOMt/9S9Lv43/JciYZYjTpnfjyl4yBGCQ8KAnBXDDBR w==; X-IronPort-AV: E=McAfee;i="6500,9779,10497"; a="306373652" X-IronPort-AV: E=Sophos;i="5.95,178,1661842800"; d="scan'208";a="306373652" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Oct 2022 02:22:03 -0700 X-IronPort-AV: E=McAfee;i="6500,9779,10497"; a="752066144" X-IronPort-AV: E=Sophos;i="5.95,178,1661842800"; d="scan'208";a="752066144" Received: from ashyti-mobl2.igk.intel.com (HELO intel.com) ([172.28.182.106]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Oct 2022 02:22:02 -0700 Date: Wed, 12 Oct 2022 11:21:59 +0200 From: Andi Shyti To: Anshuman Gupta Message-ID: References: <20221012083402.1069940-1-anshuman.gupta@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221012083402.1069940-1-anshuman.gupta@intel.com> Subject: Re: [Intel-gfx] [PATCH] drm/i915/dgfx: Temporary hammer to keep autosuspend control 'on' 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: intel-gfx@lists.freedesktop.org, matthew.auld@intel.com, rodrigo.vivi@intel.com Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Hi Anshuman, On Wed, Oct 12, 2022 at 02:04:02PM +0530, Anshuman Gupta wrote: > DGFX platforms has lmem and cpu can access the lmem objects > via mmap and i915 internal i915_gem_object_pin_map() for > i915 own usages. Both of these methods has pre-requisite > requirement to keep GFX PCI endpoint in D0 for a supported > iomem transaction over PCI link. (Refer PCIe specs 5.3.1.4.1) > > Both DG1/DG2 have a hardware bug that violates the PCIe specs > and support the iomem read write transaction over PCIe bus despite > endpoint is D3 state. > Due to above H/W bug, we had never observed any issue with i915 runtime > PM versus lmem access. > But this issue becomes visible when PCIe gfx endpoint's upstream > bridge enters to D3, at this point any lmem read/write access will be > returned as unsupported request. But again this issue is not observed > on every platform because it has been observed on few host machines > DG1/DG2 endpoint's upstream bridge does not bind with pcieport driver. > which really disables the PCIe power savings and leaves the bridge > at D0 state. > > Till we fix all issues related to runtime PM, we need > to keep autosupend control to 'on' on all discrete platforms with lmem. if it's only DG1 and DG2... why do we need to do it for every platform? Besides... is this a hack, workaround, permanent solution? Andi