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 064CE131E33 for ; Wed, 24 Jan 2024 20:29:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706128192; cv=none; b=QGceiuM+K49Gw3xda6nuhH+E2CgcII7siFfeviOPchfvXeV9Yff9ZFZ53SOguqjSiMd7PgcEWeVH9CXkXV4RMd7P7wtfsbTwuEPjFyca7F4yGwxEhfV0gKeadvmam5tt3PFCSE/O0D7Tv0AE2OgrWaJ+f0bbzuSt/nVoU7HjKaQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706128192; c=relaxed/simple; bh=FXYRRSk0uLvnCZYQKMX91IVXbm6WYEd4jBMhgoffjck=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=HtBViWbdwHnWa6cCUhC9bYFxA4HTVC7nYbEAP46Mqke5HyD9v/jwGURGIQG7R/kndCnuJzrazIb0bWWrZPmSJdC5NWMSAjZuhePYJ7YDndY28DgzFvBrwkwyrvT8BZHZLBwBBwMivGf/HpYwh9ZsDQXC4258ehkeJX/nWZL8QsM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=c3iASBSG; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="c3iASBSG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 42A3DC433F1; Wed, 24 Jan 2024 20:29:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706128191; bh=FXYRRSk0uLvnCZYQKMX91IVXbm6WYEd4jBMhgoffjck=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=c3iASBSGX6Aghzhxh8xYViHcxVVNFvMPDilZVjvuZ2oceBOTYjdHcuwmSTWOEzNUH x24vtoUErnmBWZXXuajuzMrTvYRO1NCljqYOWpQw34wWzBh1l4jx6MZmqYgtkCCbND DvBKSCa2OXIf5nIbiSXI+t7ydSO+sgHLCMYki+IuYP6MPGmxVTqPBcmI2+9G73rKTh C5sSBpVDpQoKiVWrZSihaqBHmE3AhImiK3xz/8cuikDhnrFGqb4u1+9Q6+LY1P2001 xL0JtrP1441KLa3FB7pGZvqSCwqiO7EYWaOO+2QwgRUMYkDli6uV8qHvaUlVUOhzgz 9pKdKQdRda0tQ== Date: Wed, 24 Jan 2024 14:29:49 -0600 From: Bjorn Helgaas To: Matthew W Carlis Cc: bhelgaas@google.com, kbusch@kernel.org, linux-pci@vger.kernel.org, lukas@wunner.de, mika.westerberg@linux.intel.com, sathyanarayanan.kuppuswamy@linux.intel.com Subject: Re: [PATCH 1/1] PCI/portdrv: Allow DPC if the OS controls AER natively. Message-ID: <20240124202949.GA358535@bhelgaas> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240123231834.11340-1-mattc@purestorage.com> On Tue, Jan 23, 2024 at 04:18:34PM -0700, Matthew W Carlis wrote: > Hello again! I'm glad that I'm not the only person with a little > confusion about the FW ECN regarding DPC/EDR. I would argue that DPC > wasn't tied to EDR & shouldn't have been because DPC was added in > PCI Base Spec Rev 3.1 in 2014, but there wasn't an EDR ECN till > ~2020. Anyway, that's the way it goes.. It does involve several different specs (PCIe Base for the DPC hardware feature, ACPI for the OS/firmware EDR interface, PCI Firmware for the EDR support and DPC ownership negotiation), so maybe that helps explain the muddle. > I don't want to burden the kernel with making some impossible boot > time decision here. Perhaps most of the machines in the world using > DPC will soon use EDR/SFI etc. My use cases are a bit out of the > ordinary & the ACPI specifications don't seem to have given us a > mechanism for the kernel to conclude it can use DPC without EDR > support... I don't know anything about SFI and I don't see any required connection between DPC/EDR/SFI in the PCI Firmware spec. The PCI Firmware spec requires ACPI OSes to support EDR if they want to use DPC. But I don't know that the firmware is required to actually implement the EDR functionality. Non-ACPI OSes are presumed to own DPC and all other PCIe hardware features, and I don't think EDR would be in the picture since it's an ACPI thing. > Shall I submit a patch removing CONFIG_PCIE_EDR? Perhaps the > exercise would inform me about whether its code should be in > CONFIG_PCIE_DPC or CONFIG_ACPI. That would be great! I would say CONFIG_PCIE_EDR should go away and edr.c should only be compiled if CONFIG_PCIE_DPC=y and CONFIG_ACPI=y. Bjorn