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 1A1C2605A6; Tue, 30 Jan 2024 16:08:47 +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=1706630928; cv=none; b=ZB5cl9jPmLXoaSD5BrkPXqOC6Zf6uEhFjqSCjnLCqm9+Z2/BqBueJLqbcULP+PxwhHbuvYPKXjZbnXtcluAKi2V6PZqSdawN2D8A+/ysbUY7axtbaihVqcRBHBp7JRLHE0/7Fgub57Cqfz5M3akpD9caR5Aexn6dT/SLCspS+vo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706630928; c=relaxed/simple; bh=sPfj1j3becXJ7FsukmBOZKFUKuKhbginVe76VML0cXQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=kElmla3eJaDJdyM21AqHsafQ4rtvRfxYH+43HOn0KlNJXLbPH2hKQND2x7P9re6zugsSVT4c+aQ91ilkLXqKcd0iuvqMGisrbPKhFgIz/berXh4bj8oRcB9b6P17dC3Hf2/GVX15xP1RL3fUN4Q36To2lIx/F9fmFG2KIdc0mz8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WmIFW2K2; 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="WmIFW2K2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1E2BFC433B1; Tue, 30 Jan 2024 16:08:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706630927; bh=sPfj1j3becXJ7FsukmBOZKFUKuKhbginVe76VML0cXQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=WmIFW2K2WgTsKXQmDdtFbEnUjOrbNCF8PYC4VvIFsGwbw34L19U9MYFsKAMIPCycY LC/VcY6WWhHTYIMox8e4CI2JJNi1bbfjUrGSfJdFg/SGj8Xvn87HbUGCo3GcxG6zCO 37P6GVi/kqcp5mLJbkxUDbApSuGsX9yVjfcY6GXrZyUcID/fgA8XuxTPFF6DaGEg4X 0sMYfPheUUaDyV+9PqMuZX/DdKs8mTx0h8HW4+nKLGDsGEF8cCLSOyu0rSRWIXHw9m avnV2CMbsJpUWj4scBQGRAktSei4fsapCkjhweRp+1TWvmxmAira22HmAcznJJUQyb ocuRD83nX5Kfw== Date: Tue, 30 Jan 2024 21:38:43 +0530 From: Vinod Koul To: Paul Cercueil Cc: Jonathan Cameron , Jonathan Corbet , Lars-Peter Clausen , Sumit Semwal , Christian =?iso-8859-1?Q?K=F6nig?= , Daniel Vetter , Nuno Sa , Michael Hennerich , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, linux-iio@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org Subject: Re: [PATCH v6 1/6] dmaengine: Add API function dmaengine_prep_slave_dma_vec() Message-ID: References: <20240129170201.133785-1-paul@crapouillou.net> <20240129170201.133785-2-paul@crapouillou.net> Precedence: bulk X-Mailing-List: linux-kernel@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: <20240129170201.133785-2-paul@crapouillou.net> On 29-01-24, 18:01, Paul Cercueil wrote: > This function can be used to initiate a scatter-gather DMA transfer, > where the address and size of each segment is located in one entry of > the dma_vec array. > > The major difference with dmaengine_prep_slave_sg() is that it supports > specifying the lengths of each DMA transfer; as trying to override the > length of the transfer with dmaengine_prep_slave_sg() is a very tedious > process. The introduction of a new API function is also justified by the > fact that scatterlists are on their way out. > > Note that dmaengine_prep_interleaved_dma() is not helpful either in that > case, as it assumes that the address of each segment will be higher than > the one of the previous segment, which we just cannot guarantee in case > of a scatter-gather transfer. > > Signed-off-by: Paul Cercueil > > --- > v3: New patch > > v5: Replace with function dmaengine_prep_slave_dma_vec(), and struct > 'dma_vec'. > Note that at some point we will need to support cyclic transfers > using dmaengine_prep_slave_dma_vec(). Maybe with a new "flags" > parameter to the function? that would be better > --- > include/linux/dmaengine.h | 25 +++++++++++++++++++++++++ > 1 file changed, 25 insertions(+) > > diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h > index 3df70d6131c8..ee5931ddb42f 100644 > --- a/include/linux/dmaengine.h > +++ b/include/linux/dmaengine.h > @@ -160,6 +160,16 @@ struct dma_interleaved_template { > struct data_chunk sgl[]; > }; > > +/** > + * struct dma_vec - DMA vector > + * @addr: Bus address of the start of the vector > + * @len: Length in bytes of the DMA vector > + */ > +struct dma_vec { > + dma_addr_t addr; > + size_t len; > +}; > + > /** > * enum dma_ctrl_flags - DMA flags to augment operation preparation, > * control completion, and communicate status. > @@ -910,6 +920,10 @@ struct dma_device { > struct dma_async_tx_descriptor *(*device_prep_dma_interrupt)( > struct dma_chan *chan, unsigned long flags); > > + struct dma_async_tx_descriptor *(*device_prep_slave_dma_vec)( > + struct dma_chan *chan, const struct dma_vec *vecs, > + size_t nents, enum dma_transfer_direction direction, > + unsigned long flags); s/slave/peripheral I had requested it a bit while ago as well > struct dma_async_tx_descriptor *(*device_prep_slave_sg)( > struct dma_chan *chan, struct scatterlist *sgl, > unsigned int sg_len, enum dma_transfer_direction direction, > @@ -972,6 +986,17 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_single( > dir, flags, NULL); > } > > +static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_dma_vec( > + struct dma_chan *chan, const struct dma_vec *vecs, size_t nents, > + enum dma_transfer_direction dir, unsigned long flags) > +{ > + if (!chan || !chan->device || !chan->device->device_prep_slave_dma_vec) > + return NULL; > + > + return chan->device->device_prep_slave_dma_vec(chan, vecs, nents, > + dir, flags); > +} > + > static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_sg( > struct dma_chan *chan, struct scatterlist *sgl, unsigned int sg_len, > enum dma_transfer_direction dir, unsigned long flags) > -- > 2.43.0 -- ~Vinod