From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 35D103C46A; Thu, 14 Dec 2023 17:28:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="XSEj/glB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF9B0C433C9; Thu, 14 Dec 2023 17:28:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1702574930; bh=P8WIww2274+m+ez0eGWOb23W8iwkilWxoapMNkXmSoI=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=XSEj/glB2zBkw6SiLPvUtM7upEYS6XnUikmteJZhAXnZflzbW9uW2qbKlLuj8JaR3 UhCXpC+lFeRGOw1IH9McsmcQIHs88KaO0Zm++1VMWO0glWqQbsdtsF9It0QV/TVoeK tizuaDJFXwxG+GqeCFsx5zJVqjTyuJt7syIyQXYW+tgvVRDUw022BVmN4duObs3PK0 gx3rV4ogqff+iZhJ3WSTWwtSNdqoH8GuBE9oNeW9qYcb7dHFDqtBzlcgFPhTQOu9um BUFF59MaswASLf/oCfWgvWtd1L4cH6+ERTkVa6W5wGNh642111BGBanJ0MsJQLXH4g QX8Sj6bAewScw== Date: Thu, 14 Dec 2023 11:28:48 -0600 From: Bjorn Helgaas To: "David E. Box" Cc: Kai-Heng Feng , Johan Hovold , Lorenzo Pieralisi , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Bjorn Helgaas , Andy Gross , Bjorn Andersson , Konrad Dybcio , Manivannan Sadhasivam , Rob Herring , Nirmal Patel , Jonathan Derrick , linux-arm-msm@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Manivannan Sadhasivam Subject: Re: [PATCH v2 1/6] PCI/ASPM: Add locked helper for enabling link state Message-ID: <20231214172848.GA1095194@bhelgaas> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Wed, Dec 13, 2023 at 03:39:24PM -0800, David E. Box wrote: > On Wed, 2023-12-13 at 14:45 -0600, Bjorn Helgaas wrote: > ... > > I'd be shocked if Windows treated the BIOS config as a "do not exceed > > this" situation, so my secret hope is that some of these "broken" > > devices are really caused by defects in the Linux ASPM support or the > > driver, and that we can fix them if we find out about them. > > > > But I have no details about any of these alleged broken devices, so > > it's hard to make progress on them.   > > I don't have a sense of the scope either. But I could see BIOS not > enabling features that would provide no added power savings benefit. > We use ASPM to manage package power. There are Intel devices that > certainly don't require L1SS for the SoC to achieve the deepest > power savings. L1 alone is fine for them. I don't know what the test > coverage is for unenabled features. I've sent these questions to > our BIOS folks. Once upon a time there was a push to make it so firmware only had to enumerate boot and console devices and it could skip enumeration and configuration of other devices. But I don't think we've made much progress on that, at least for x86, possibly because Linux depends so much on BIOS resource assignment. IMO that's a Linux deficiency. Bjorn