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 321732ED860; Wed, 3 Dec 2025 10:39:28 +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=1764758369; cv=none; b=LUpi/5qWbeaeIPIiEfWaKOo/sfuxldFPKWHWDBiPDsaguhT8VkaJYu3rDJ42S4F35Wh20a7JlIdheY5ZtTLQiVK3ygRuFRejxTYIPSV3oxtWTz+TTSMewIv6gxmJY74OJ+9rATvzu2qerwCiV5MybiAPqD416GfPjHT9owNjccg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764758369; c=relaxed/simple; bh=TLBlsGSLsSIAD6kDe9cUxlU+9iuTV0gMwtHNAzccloc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=LkKOjBSApyJBKsVitSXjoP4aKlyFE/wPV+Atq2M1AjhO1c4jqGuaud+95sgYqwnvFNF6Dn2MMwbbbYNrM9AWX/Xt3cZUjR7xn9Etx+lVXQOxmzSkIqG+GMgCbSzI87PLXOC/1Up5jtBRmdd6qPF7iOuZ5z9u+TkBIQZTcSlctO0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=et4xYk5h; 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="et4xYk5h" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5F189C4CEFB; Wed, 3 Dec 2025 10:39:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764758368; bh=TLBlsGSLsSIAD6kDe9cUxlU+9iuTV0gMwtHNAzccloc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=et4xYk5h44EL2L+Ku72VBPYS4J8Y+XWKAj7xjtSPfXIneLcslFxUXA+iSrCZBaMzk 466J15UKAhQp94skS0BrJJ3GxkoEW3evFGBFFpu5AFzpP/fTC06DaQx0K0kEhK8ZVC mMW8bkmW4hjWBAarxAOHEDVQ7y56B8Bxx4wtlCcDjhch3SHlnqhfKMreANVUCN2e+I rYHZ8LcpBvT6x1nD9t0ccH+oDcQexzyjDd+gl+1VJ888aDyoeujrPkjPfSdl0SL2O8 O3MTOWYKXc0ouvbTfep9Ys0pg3hFYkdEwNe2lmy16YrR7RuFXLDIvnJaII2WCaT1AM HE5wk0CK/K4cQ== Date: Wed, 3 Dec 2025 11:39:21 +0100 From: Niklas Cassel To: Koichiro Den Cc: Frank Li , ntb@lists.linux.dev, linux-pci@vger.kernel.org, dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, mani@kernel.org, kwilczynski@kernel.org, kishon@kernel.org, bhelgaas@google.com, corbet@lwn.net, vkoul@kernel.org, jdmason@kudzu.us, dave.jiang@intel.com, allenbh@gmail.com, Basavaraj.Natikar@amd.com, Shyam-sundar.S-k@amd.com, kurt.schwemmer@microsemi.com, logang@deltatee.com, jingoohan1@gmail.com, lpieralisi@kernel.org, robh@kernel.org, jbrunet@baylibre.com, fancer.lancer@gmail.com, arnd@arndb.de, pstanner@redhat.com, elfring@users.sourceforge.net, Damien Le Moal Subject: Re: [RFC PATCH v2 19/27] PCI: dwc: ep: Cache MSI outbound iATU mapping Message-ID: References: <20251129160405.2568284-1-den@valinux.co.jp> <20251129160405.2568284-20-den@valinux.co.jp> Precedence: bulk X-Mailing-List: dmaengine@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: On Wed, Dec 03, 2025 at 05:40:45PM +0900, Koichiro Den wrote: > > > > If we want to improve the dw-edma driver, so that an EPF driver can have > > multiple outstanding transfers, I think the best way forward would be to create > > a new _prep_slave_memcpy() or similar, that does take a direction, and thus > > does not require dmaengine_slave_config() to be called before every > > _prep_slave_memcpy() call. > > Would dmaengine_prep_slave_single_config(), which Frank tolds us in this > thread, be sufficient? I think that Frank is suggesting a new dmaengine API, dmaengine_prep_slave_single_config(), which is like dmaengine_prep_slave_single(), but also takes a struct dma_slave_config * as a parameter. I really like the idea. I think it would allow us to remove the mutex in nvmet_pci_epf_dma_transfer(): https://github.com/torvalds/linux/blob/v6.18/drivers/nvme/target/pci-epf.c#L389-L429 Frank you wrote: "Thanks, we also consider ..." Does that mean that you have any plans to work on this? I would definitely be interested. Kind regards, Niklas