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 2848C1C4A0C for ; Mon, 4 Nov 2024 22:04:31 +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=1730757872; cv=none; b=BAZK107WlFvloaY8DEBavyvglO2U70/hF63dZOSnjMG5vnI24iVsIBhG68ZOVW6tRvFKX4aW7gTfL0aigmLCVSUdEK0QCbYue4dEW+gzT6chytOZ9rOgaVff5sBHa1S5TogEhHNbKG1oQSc161OVoa77nFyYMgpF3o0FX4Cp3sE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730757872; c=relaxed/simple; bh=rpQvxNAKO54BaQ7y9JfUYcOtSRlRPeKBYf5D0e3CD/I=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Tvoni8PT46UrxLq6/oP7c0tgL1fCcrxo7JdArYsGU5UoJ/aprBMe4Yl78b41LIB6zDjNNANdoTepEZJz2Q7Pz1KUieQW6GQCRAD4kEv+oHlLu1CBl+ls3XX3zPSRbpmtld0YNMtaqYJwcp5Xje/p4zQlD/kVpSmzBuhGr8LBNdU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Jz5Gf/nO; 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="Jz5Gf/nO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB975C4CECE; Mon, 4 Nov 2024 22:04:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730757871; bh=rpQvxNAKO54BaQ7y9JfUYcOtSRlRPeKBYf5D0e3CD/I=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Jz5Gf/nO1G9kENkMOwjVKx8Q0kzAu6Z9ZaqnRY4FJOtLUmoPZqMPjsN2cgqFQoWws sImIHvrqfWfsmHbeIHYZavwsmE1/vbQMwGvP3qxUaKhpRtk7iPZqD+BVauuXdNSp/z HcuVBWLvDsFe6Oao5eJWVZc119NW3J1pgK3s06eQaN7VdPwDWoONlHdf0XlHUZJ2CM o8I2wCLKlQuBIgTbnFLy9s0Y3n0IiwKbfIsz7IrDC25431tpyxoZ3RqavPMe5lOZAh PFGHFArgdQoZz8XMmxv/xKq4UeVNYGnfUxWfPpBKa9K7blsZ2shz34NN1jzw7VPMHE aInMsVbiIlRcA== Date: Mon, 4 Nov 2024 23:04:26 +0100 From: Niklas Cassel To: Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= Cc: Jingoo Han , Manivannan Sadhasivam , Lorenzo Pieralisi , Rob Herring , Bjorn Helgaas , Damien Le Moal , Frank Li , linux-pci@vger.kernel.org Subject: Re: [PATCH] PCI: dwc: ep: Do not map more memory than needed to raise a MSI/MSI-X IRQ Message-ID: References: <20241104205144.409236-2-cassel@kernel.org> <20241104211354.GB880663@rocinante> 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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20241104211354.GB880663@rocinante> On Tue, Nov 05, 2024 at 06:13:54AM +0900, Krzysztof Wilczyński wrote: > Hello, > > > In dw_pcie_ep_init() we allocate memory from the EPC address space that we > > will later use to raise a MSI/MSI-X IRQ. This memory is only freed in > > dw_pcie_ep_deinit(). > > > > Performing this allocation in dw_pcie_ep_init() is to ensure that we will > > not fail to allocate memory from the EPC address space when trying to raise > > a MSI/MSI-X IRQ. > > > > We still map/unmap this memory every time we raise an IRQ, in order to not > > constantly occupy an iATU, especially for controllers with few iATUs. > > (So we can still fail to raise an MSI/MSI-X IRQ if all iATUs are occupied.) > > > > When allocating this memory in dw_pcie_ep_init(), we allocate > > epc->mem->window.page_size memory, which is the smallest unit that we can > > allocate from the EPC address space. > > > > However, when writing/sending the msg data, which is only 2 bytes for MSI, > > 4 bytes for MSI-X, in either case a single writel() is sufficient. Thus, > > the size that we need to map is a single PCI DWORD (4 bytes). > > > > This is the size that we should send in to the pci_epc_ops::align_addr() > > API. It is align_addr()'s responsibility to return a size that is aligned > > to the EPC page size, for platforms that need a special alignment. > > > > Modify the align_addr() call to send in the proper size that we need to > > map. > > > > Before this patch on a system with a EPC page size 64k, we would > > incorrectly map 128k (which is larger than our allocation) instead of 64k. > > > > After this patch, we will correctly map 64k (a single page). (We should > > never need to map more than a page to write a single DWORD.) > [...] > > Feel free to squash this with the patch that it fixes, if you so prefer. > > Squashed with the rest of the pending changes, per: > > https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/commit/?h=endpoint&id=d2d9f84914e147d6ee399e0ed8d938fea7f0c35c > > Let me know if anything needs to be updated there. Thank you Krzysztof! I do not see any point in you adding my Co-developed-by tag since I'm the Author: of the original commit (the commit that you squashed with). As far as I know, the Co-developed-by tag should only be added since there can only be one person marked as Author: And perhaps: [kwilczynski: squashed patch that fixes memory map sizes on platforms with EPC page size of 64k] should be: [kwilczynski: squashed patch that fixes memory map sizes on all platforms] or just: [kwilczynski: squashed patch that fixes memory map sizes] Since I (embarrassingly) always mapped twice as much memory as needed in the original commit. The squashed commit itself looks correct :) Kind regards, Niklas