From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.19]) (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 DE9094B1D0E; Mon, 21 Sep 2026 16:43:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.19 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790009027; cv=none; b=tPSK1Be0qLA2SY4MduQU6crwpncpcjad3ObBd+Z4lQp/fPZl+FAlnGacRoeKzReckAmAMPLapPGPdJcZqYS1T2DAvZUh5B3TL8z/XT9lpCCHwCFkeDg2rJqq0krqaRCk6qKxz1mjnZbkF/6jkNH0GFtzP1hzSULrXUclrGtGnUs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790009027; c=relaxed/simple; bh=eM1N6XqzmlgwM+AO0lHdun00OVqdgvGXGEqNfHmMGAk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=GLwLl9QLN+8GoIvZNlGZFhEAGjDuKy0mgiesPhjoEwfE3ooZrY/q1Wtk1e5eCK1bsnOEJYDqgMXpkaCU/F2OoPpJJPBH5C0Tiv5KhR7aqgYiWTOm44x7RiP18O4bvpjjKtFZrjD3/vwdnDvosurv0OQPgNEKZYH8YrEokcnq9xg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=AJQZM8ow; arc=none smtp.client-ip=192.198.163.19 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="AJQZM8ow" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1790009025; x=1821545025; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=eM1N6XqzmlgwM+AO0lHdun00OVqdgvGXGEqNfHmMGAk=; b=AJQZM8owqDfGy2fKQjcW2wcwsIXtUwZzxifcAFBj2rdVjSXMjIkF02Ww 8K1OtYQ6Dy0MNc3VngURsjtIuO18XKVKCVBhGGQXUWHL5D9lCgvPnNCQ3 Ve6q3IELrrJ4BzUBR3GGpD6/H79aIPQ9qKVEXxR8JEvnK4O5/b9X/4fhp usvw3Z4Q8aro45rgaPdIrpQsXszIYnT78mVdrMWV03+DR16Crg16/bRsA vg0LeQaSidyh6DYmJkuurhNztVkWPQrQlxdjOPKcI2z/64wK/GbdPkdR5 aWK7cd5rikdUfsTFXmdX67TwxIhMAQVXqy0xd35OjIGddq1Ku0uO6kE4d g==; X-CSE-ConnectionGUID: vJgVAQtkS8ucWoNWGLGn4Q== X-CSE-MsgGUID: Kz4sWl00Tm2ONPwzERI6Ig== X-IronPort-AV: E=McAfee;i="6800,10657,11912"; a="89467285" X-IronPort-AV: E=Sophos;i="6.27,115,1787036400"; d="scan'208";a="89467285" Received: from fmviesa001.fm.intel.com ([10.60.135.141]) by fmvoesa113.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Sep 2026 09:43:44 -0700 X-CSE-ConnectionGUID: Ov5NmTY/SoKvcsbUdfn5ZA== X-CSE-MsgGUID: QX0iXJS2R9+E9w6/jnlkFQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,115,1787036400"; d="scan'208";a="300684514" Received: from soc-pf446t5c.clients.intel.com (HELO [10.24.80.90]) ([10.24.80.90]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Sep 2026 09:43:44 -0700 Message-ID: <24b9db58-e654-408b-85a9-15c5af5e944a@linux.intel.com> Date: Mon, 21 Sep 2026 09:43:43 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v13 1/5] PCI/DPC: Ignore devices with no AER Capability To: Lukas Wunner Cc: Bjorn Helgaas , linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, Rafael J Wysocki , Guixin Liu , Olof Johansson References: <20260919162655.3499010-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20260919162655.3499010-2-sathyanarayanan.kuppuswamy@linux.intel.com> Content-Language: en-US From: Kuppuswamy Sathyanarayanan In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Lukas, On 9/19/2026 11:11 PM, Lukas Wunner wrote: > On Sat, Sep 19, 2026 at 09:26:51AM -0700, Kuppuswamy Sathyanarayanan wrote: >> Downstream Ports may support DPC regardless of whether they support AER >> (see PCIe r7.0, sec 6.2.11.2). Previously, if the user booted with >> "pcie_ports=dpc-native", it was possible for dpc_probe() to succeed even if >> the device had no AER Capability, but dpc_get_aer_uncorrect_severity() >> depends on the AER Capability. > [...] >> +++ b/drivers/pci/pcie/dpc.c >> @@ -477,6 +477,9 @@ static int dpc_probe(struct pcie_device *dev) >> int status; >> u16 cap; >> >> + if (!pdev->aer_cap) >> + return -ENOTSUPP; >> + >> if (!pcie_aer_is_native(pdev) && !pcie_ports_dpc_native) >> return -ENOTSUPP; > > I've got patches which make DPC work (again) on AER-unsupporting ports: > > https://github.com/l1k/linux/commits/aer_baseline_v1/ > > In particular: > > PCI/DPC: Avoid access to non-existent AER capability > https://github.com/l1k/linux/commit/85f209fd4732 > > PCI/DPC: Reinstate support for AER-incapable ports > https://github.com/l1k/linux/commit/2de89b762d79 > > I'm almost done with that series and hope to submit it this cycle. > Your patch [1/5] will cause a conflict with my patches. > Would you mind holding off on patch [1/5] for now? Sure. At first glance, your series fixes the AER/DPC dependency cleanly. I think we can drop this patch. Bjorn, let me know if you think otherwise. > > There's another reason: I know of one product in particular, > Intel "Ponte Vecchio" data center GPUs, which support DPC but > lack an AER capability. DPC was tested and made to work on > those cards (see 53b54ad074de). > > I didn't realize back then but know now that validation engineers > specifically used pcie_ports=dpc-native to be able to use DPC on > that product. And I believe this was also communicated to customers > as "best known method" for DPC on Ponte Vecchio. In other words, > using pcie_ports=dpc-native to make DPC work on non-AER-capable products > has become a feature. Your patch breaks those use cases. > > That's why I chose to make DPC work (again) on non-AER-capable products > with the above-linked patches, instead of closing this loophole to > force-enable it. > > Thanks, > > Lukas -- Sathyanarayanan Kuppuswamy Linux Kernel Developer