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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 0AC93E77197 for ; Tue, 7 Jan 2025 23:12:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To: Content-Transfer-Encoding:Content-Type:MIME-Version:Message-ID:Subject:Cc:To: From:Date:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:References:List-Owner; bh=p1Kkoignyrr80sETDjSCu3E4vA6Ej0aacljRgloDpT4=; b=O3lWjulZ+IgocnjdA4NK9Izywa Ml9UpSjOzrLHhCkm+9kgv/6AOVNo5xT+iRWraYcqmJzFiy7Y7EtsTIY8cPIyzbMQrR2SyGffA8Prh Qiy1nrB4TsrIAgB/G+CvGlZUlxw9+GEp1ZONbwx/+LbkbQSWtxOONP8Q6SKB7LCZdvbkjQlgh98At ZYQhV86Gio/6V0uV/YPHNUUghGlO5dS8LjGPi7ug+ZXz6LYKDIjHUNyEphKAvZIYy59sTZuj75F5i 3uVq4Vr/dUnsbNM7ODUtXP/koDPzGWP3LJjqbpZ0A6sRZk9vNGJ6ruReBp2y+wnsmP+x7I0qixS+F O79M2EMg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tVIkQ-00000006VTJ-0FN3; Tue, 07 Jan 2025 23:12:30 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tVIfo-00000006UXy-2K1d; Tue, 07 Jan 2025 23:07:45 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id F08B95C0FD3; Tue, 7 Jan 2025 23:07:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 99020C4CEDF; Tue, 7 Jan 2025 23:07:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1736291263; bh=qCOsJ/wKHOi3SAkDBRYfIUDYbFC/ozgvyeH4knr/FXA=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=Lbv4lvYyU3hdnUYszWRuxX22YRUZGI6KXGwtAZ0QayGT7PHOTKKa0IPoqG2EmSchl 3Pk0IAVh3ynu5a8qsvbVQP++4PaPE443CgJi9TVTTWGQzlKlrGgvo4osLY/vyk+2Ae s5krWEJBDP+TCUCS1YTlph1APAIQQ61PXi4BCdyPtzWJzAvC2Uta6zK6MzxXxwCr6C EAPGePwBBXgrMCetp9aLHjjMHQgqLXnt1AGjcrr9nInknI5OvElB86o160HIRO2cA/ Tngd46xXYTVXCCH2EcaYrvWGXqVztxxk+xxl5jSodUU/D0RvS8VeWoGF49vYkMeQVg 1mvrlRa1FVllA== Date: Tue, 7 Jan 2025 17:07:42 -0600 From: Bjorn Helgaas To: AngeloGioacchino Del Regno Cc: Jianjun Wang =?utf-8?B?KOeOi+W7uuWGmyk=?= , "manivannan.sadhasivam@linaro.org" , "conor+dt@kernel.org" , "robh@kernel.org" , "kw@linux.com" , "bhelgaas@google.com" , "matthias.bgg@gmail.com" , "krzk+dt@kernel.org" , "lpieralisi@kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" , "linux-mediatek@lists.infradead.org" , Ryder Lee , "devicetree@vger.kernel.org" , Xavier Chang =?utf-8?B?KOW8teeNu+aWhyk=?= Subject: Re: [PATCH 3/5] PCI: mediatek-gen3: Disable ASPM L0s Message-ID: <20250107230742.GA189563@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1a48feae-f55f-4df8-b165-84c1cb2f6658@collabora.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250107_150744_640329_D65073BA X-CRM114-Status: GOOD ( 23.50 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jan 07, 2025 at 12:44:43PM +0100, AngeloGioacchino Del Regno wrote: > Il 07/01/25 03:18, Jianjun Wang (王建军) ha scritto: > > On Fri, 2025-01-03 at 10:16 +0100, AngeloGioacchino Del Regno wrote: > > > Il 03/01/25 07:00, Jianjun Wang ha scritto: > > > > Disable ASPM L0s support because it does not significantly save > > > > power > > > > but impacts performance. > > > > > > That may be a good idea but, without numbers to support your > > > statement, it's a bit > > > difficult to say. > > > > > > How much power does ASPM L0s save on MediaTek SoCs, in microwatts? > > > How is the performance impacted, and on which specific device(s) on > > > the PCIe bus? > > > > It's hard to tell the exact number because it is difficult to measure, > > and the number of entries into the L0s state may vary even in the same > > test scenario. > > > > However, we have encountered some compatibility issues when connected > > with some PCIe EPs, and disabling the L0s can fix it. I think disabling > > L0s might be the better way, since we usually use L1ss for power-saving > > when the link is idle. > > To actually decide, we should know what's actually broken, then. > > Is the MediaTek controller broken, or is the device broken? > So, is it a MTK quirk, or a device quirk? > > If the problem is actually device-related, then this should be handled as > a device-specific quirk, as not just MediaTek platforms would be affected > by compatibility issues. > > If the MediaTek PCIe controller is at fault, instead, I agree about just > disabling L0s at the controller level - but then this shall be mentioned > in the commit message, and should have a Fixes tag as well. 100% agreed, sorry for repeating what you just said before I finished reading the thread! Bjorn