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 0378038D009; Mon, 2 Mar 2026 10:07:24 +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=1772446045; cv=none; b=GDrvZ6h1Bv+o4ChjzEnW6JIZuWVUxIYFRLxG7kk/UY0AI+Hcb9GcRq2nWMVsip6MOLVseLjhiqest2mhV6bYibVvVckbUY+oCdHy8fyjFgd2xl1LN3CyiykgP5cfi/DwObUOVqNhGWbxwoL1z1n8eakqygC0hU3LkkqXAbKzOCg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772446045; c=relaxed/simple; bh=WsKalQsrcTrCExLvVUrum2up311uMNa/m5xaR9444CU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=cKUgjRqPYvrW7fJFSMlKKGMV3BEqWHAbwztfqkwM1Q9O0kiFSHvxYK0uJEnWKmM/LOBZyccsWugPE4KZ0WgYDm2A1bjFnf31h4I6QZ3e6HpfO8h9XDqcilIqmlTcnBXKPslUfAAz0hx3+8AhqeVEbS9QzCfONFt3l6De94g47GI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Idz31Tul; 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="Idz31Tul" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A777EC19423; Mon, 2 Mar 2026 10:07:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772446044; bh=WsKalQsrcTrCExLvVUrum2up311uMNa/m5xaR9444CU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Idz31TulenK2Oc1qZMZYRCZDv8zLtAmYydFFwom9nMBYmPgd6yBncrGZAh3Pg335B nmAHJZMBGDjYDlv9jugT9XKsO0WupC4YCvHNdKxGdW+JXnx6MTf7iIpJV9jFONn6ME NOlr4q6ld56SACyoBRcsCp7d38sRhxYj9Bjq9nq7EhO8gCc63vlU1RTd6y9e32GtQX aiQaUa30Z4cNrtJ5V4/j9nekmGF0hrTp/ILbHE+AInsEbOWy7mIha0SWLkKRhDp09c 97W5FBBeHxRJ9nC4On0vYFBYnMV+P1PM2AEqO7ziDFKiJC7SbJHQffyrzOSegmcGRR 4T0CanHLhEOBA== Date: Mon, 2 Mar 2026 11:07:17 +0100 From: Niklas Cassel To: Koichiro Den Cc: Jingoo Han , Manivannan Sadhasivam , Lorenzo Pieralisi , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Rob Herring , Bjorn Helgaas , Kishon Vijay Abraham I , Jon Mason , Dave Jiang , Allen Hubbe , Frank Li , Bhanu Seshu Kumar Valluri , Marco Crivellari , Shin'ichiro Kawasaki , Manikanta Maddireddy , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, ntb@lists.linux.dev Subject: Re: [PATCH v10 7/7] PCI: endpoint: pci-ep-msi: Add embedded doorbell fallback Message-ID: References: <20260302071427.534158-1-den@valinux.co.jp> <20260302071427.534158-8-den@valinux.co.jp> 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: <20260302071427.534158-8-den@valinux.co.jp> On Mon, Mar 02, 2026 at 04:14:27PM +0900, Koichiro Den wrote: > Some endpoint platforms cannot use platform MSI / GIC ITS to implement > EP-side doorbells. In those cases, EPF drivers cannot provide an > interrupt-driven doorbell and often fall back to polling. > > Add an "embedded" doorbell backend that uses a controller-integrated > doorbell target (e.g. DesignWare integrated eDMA interrupt-emulation > doorbell). > > The backend locates the doorbell register and a corresponding Linux IRQ > via the EPC aux-resource API. If the doorbell register is already > exposed via a fixed BAR mapping, provide BAR+offset. Otherwise provide > the DMA address returned by dma_map_resource() (which may be an IOVA > when an IOMMU is enabled) so EPF drivers can map it into BAR space. > > When MSI doorbell allocation fails with -ENODEV, > pci_epf_alloc_doorbell() falls back to this embedded backend. > > Signed-off-by: Koichiro Den > --- Tested-by: Niklas Cassel