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 1D10D2253FC; Fri, 19 Dec 2025 10:33:46 +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=1766140427; cv=none; b=eowBTuve2CMfj6dyC920xQmSPvTMDPZLvZlIR4NBN3H/BVpFyjnRvEZo2O0ykulpbYuAAleV2Yp+zi9W6bEJWEjr2f3Pa7RxEqbRrdSfwYx2HHpJj3vPjo/WUVj61gNi3rL8ONQC9kELjg3Ep4aGFAKlDAxQbjgpTVfNGFQ1koY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766140427; c=relaxed/simple; bh=dtZQq9Tz8X9IApzFIIAr/KFy4FgR9nC4AkGBbD+ruV4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=RKIfwxWWMEBo/7AhgwVRXoU98YQD1tZhZsPjMk3Ejy4ecsfn95Yk9VF40ktBn9h/TV9p/Ozl30DghYI4WDu1eEcsdi/kRZnkjRfMmX7asK6mFewGC6ur5STcDHoivZEXHcsZOs0vtQyrjdNMqv+4F1ykgZI8T4vFtmSrkvxpk78= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dvhFZA9m; 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="dvhFZA9m" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 96CA0C4CEF1; Fri, 19 Dec 2025 10:33:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1766140426; bh=dtZQq9Tz8X9IApzFIIAr/KFy4FgR9nC4AkGBbD+ruV4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=dvhFZA9mSqbLJ4yx1jwkajLjdYyJpg/f+9SuszQZkDtJpoVGrKr+VuyI2UpSTAk63 TbgkCcHbt6vnU8Dl3ct5fdt4iBv5tNkB3tpX0Ymis8/x5zv4SfOtQfEcVOrNwoPr9d o/TqZs5FaoTMNrlNnl00Lylv9lHjgr2455clLXs9cY+cW7ut5VonZQRs2WBZw5JhQN qr7EiJyCLb8rxiesfFq0oCoVFmMig7iSpgXbkpL+6dL9bdP2ZAwrUZLFqsJjtL4uF8 Cq4Odqpe3E285Sx/9maLb8nrVVpavMQg9va7oh7H1FeAJgKgnoLQPS5eiDC9K7Z9/y a8J56MSdiktog== Message-ID: Date: Fri, 19 Dec 2025 19:33:42 +0900 Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/8] dmaengine: Add API to combine configuration and preparation (sg and single) To: Frank Li , Vinod Koul , Manivannan Sadhasivam , =?UTF-8?Q?Krzysztof_Wilczy=C5=84ski?= , Kishon Vijay Abraham I , Bjorn Helgaas , Christoph Hellwig , Sagi Grimberg , Chaitanya Kulkarni , Herbert Xu , "David S. Miller" , Nicolas Ferre , Alexandre Belloni , Claudiu Beznea , Koichiro Den , Niklas Cassel Cc: dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-nvme@lists.infradead.org, mhi@lists.linux.dev, linux-arm-msm@vger.kernel.org, linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org, imx@lists.linux.dev References: <20251218-dma_prep_config-v2-0-c07079836128@nxp.com> <20251218-dma_prep_config-v2-1-c07079836128@nxp.com> Content-Language: en-US From: Damien Le Moal Organization: Western Digital Research In-Reply-To: <20251218-dma_prep_config-v2-1-c07079836128@nxp.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 12/19/25 00:56, Frank Li wrote: > Previously, configuration and preparation required two separate calls. This > works well when configuration is done only once during initialization. > > However, in cases where the burst length or source/destination address must > be adjusted for each transfer, calling two functions is verbose and > requires additional locking to ensure both steps complete atomically. > > Add a new API dmaengine_prep_config_single() and dmaengine_prep_config_sg() > and callback device_prep_config_sg() that combines configuration and > preparation into a single operation. If the configuration argument is > passed as NULL, fall back to the existing implementation. > > Add a new API dmaengine_prep_config_single_safe() and > dmaengine_prep_config_sg_safe() for re-entrancy, which require driver > implement callback device_prep_config_sg(). > > Tested-by: Niklas Cassel > Signed-off-by: Frank Li > --- > change in v2 > - add () for function > - use short name device_prep_sg(), remove "slave" and "config". the 'slave' > is reduntant. after remove slave, the function name is difference existed > one, so remove _config suffix. > --- > Documentation/driver-api/dmaengine/client.rst | 9 +++ > include/linux/dmaengine.h | 103 ++++++++++++++++++++++++-- > 2 files changed, 105 insertions(+), 7 deletions(-) > > diff --git a/Documentation/driver-api/dmaengine/client.rst b/Documentation/driver-api/dmaengine/client.rst > index d491e385d61a98b8a804cd823caf254a2dc62cf4..02c45b7d7a779421411eb9c68325cdedafcfe3b1 100644 > --- a/Documentation/driver-api/dmaengine/client.rst > +++ b/Documentation/driver-api/dmaengine/client.rst > @@ -80,6 +80,10 @@ The details of these operations are: > > - slave_sg: DMA a list of scatter gather buffers from/to a peripheral > > + - config_sg: Similar with slave_sg, just pass down dma_slave_config > + struct to avoid call dmaengine_slave_config() every time if need ...struct to avoid calling dmaengine_slave_config() every time adjusting the burst length or the FIFO address is needed. > + adjust burst length or FIFO address. > + > +static inline struct dma_async_tx_descriptor * > +dmaengine_prep_config_single_safe(struct dma_chan *chan, dma_addr_t buf, > + size_t len, enum dma_transfer_direction dir, unsigned long flags, > + struct dma_slave_config *config) > { > struct scatterlist sg; > + > sg_init_table(&sg, 1); > sg_dma_address(&sg) = buf; > sg_dma_len(&sg) = len; > > - if (!chan || !chan->device || !chan->device->device_prep_slave_sg) > + if (!chan || !chan->device || !chan->device->device_prep_config_sg) > + return NULL; While at it, please move this arguments check before the sg initialization. Otherwise, this is a little odd (argument checks generally are done first). > + > + return chan->device->device_prep_config_sg(chan, &sg, 1, dir, > + flags, config, NULL); > +} > + > +static inline struct dma_async_tx_descriptor * > +dmaengine_prep_config_single(struct dma_chan *chan, dma_addr_t buf, size_t len, > + enum dma_transfer_direction dir, unsigned long flags, > + struct dma_slave_config *config) > +{ > + struct scatterlist sg; > + > + sg_init_table(&sg, 1); > + sg_dma_address(&sg) = buf; > + sg_dma_len(&sg) = len; > + > + if (!chan || !chan->device) > + return NULL; Same here. Check these before initializing sg. > + > + if (chan->device->device_prep_config_sg) > + return dmaengine_prep_config_sg_safe(chan, &sg, 1, dir, > + flags, config); > + > + if (config) > + if (dmaengine_slave_config(chan, config)) > + return NULL; > + > + if (!chan->device->device_prep_slave_sg) > return NULL; > > return chan->device->device_prep_slave_sg(chan, &sg, 1, > dir, flags, NULL); > } > > +static inline struct dma_async_tx_descriptor * > +dmaengine_prep_slave_single(struct dma_chan *chan, dma_addr_t buf, size_t len, > + enum dma_transfer_direction dir, > + unsigned long flags) > +{ > + return dmaengine_prep_config_single(chan, buf, len, dir, flags, NULL); > +} > + > /** > * dmaengine_prep_peripheral_dma_vec() - Prepare a DMA scatter-gather descriptor > * @chan: The channel to be used for this descriptor > @@ -1009,17 +1079,36 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_peripheral_dma_vec( > dir, flags); > } > > -static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_sg( > +static inline struct dma_async_tx_descriptor *dmaengine_prep_config_sg( Very odd line split. Please split this after the "*" of the return type. > struct dma_chan *chan, struct scatterlist *sgl, unsigned int sg_len, > - enum dma_transfer_direction dir, unsigned long flags) > + enum dma_transfer_direction dir, unsigned long flags, > + struct dma_slave_config *config) > { > - if (!chan || !chan->device || !chan->device->device_prep_slave_sg) > + if (!chan || !chan->device) > + return NULL; > + > + if (chan->device->device_prep_config_sg) > + return dmaengine_prep_config_sg_safe(chan, sgl, sg_len, > + dir, flags, config); > + > + if (config) > + if (dmaengine_slave_config(chan, config)) > + return NULL; > + > + if (!chan->device->device_prep_slave_sg) > return NULL; > > return chan->device->device_prep_slave_sg(chan, sgl, sg_len, > dir, flags, NULL); > } > > +static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_sg( Same comment here. > + struct dma_chan *chan, struct scatterlist *sgl, unsigned int sg_len, > + enum dma_transfer_direction dir, unsigned long flags) > +{ > + return dmaengine_prep_config_sg(chan, sgl, sg_len, dir, flags, NULL); > +} > + > #ifdef CONFIG_RAPIDIO_DMA_ENGINE > struct rio_dma_ext; > static inline struct dma_async_tx_descriptor *dmaengine_prep_rio_sg( > -- Damien Le Moal Western Digital Research