Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752053AbdGDGLB (ORCPT ); Tue, 4 Jul 2017 02:11:01 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:58044 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750921AbdGDGK7 (ORCPT ); Tue, 4 Jul 2017 02:10:59 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 21EE26081B Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=architt@codeaurora.org From: Archit Taneja Subject: Re: [PATCH 06/14] qcom: mtd: nand: add bam dma descriptor handling To: Abhishek Sahu , dwmw2@infradead.org, computersforpeace@gmail.com, boris.brezillon@free-electrons.com, marek.vasut@gmail.com, richard@nod.at, cyrille.pitchen@wedev4u.fr, robh+dt@kernel.org, mark.rutland@arm.com Cc: linux-mtd@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, andy.gross@linaro.org, sricharan@codeaurora.org References: <1498720566-20782-1-git-send-email-absahu@codeaurora.org> <1498720566-20782-7-git-send-email-absahu@codeaurora.org> Message-ID: <021637c8-8ce5-c54e-0254-41caa475063c@codeaurora.org> Date: Tue, 4 Jul 2017 11:40:51 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: <1498720566-20782-7-git-send-email-absahu@codeaurora.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6640 Lines: 209 On 06/29/2017 12:45 PM, Abhishek Sahu wrote: > 1. prepare_bam_async_desc is the function which will call > all the DMA API’s. It will fetch the outstanding scatter gather > list for passed channel and will do the DMA descriptor formation. > The DMA flag is dependent upon the type of channel. > > 2. For ADM DMA, the descriptor is being formed for every DMA > request so its sgl count will be always 1 while in BAM DMA, the > clubbing of descriptor is being done to increase throughput. > > 3. ADM uses only one channel while in BAM, data descriptors > will be submitted to tx channel (for write) or rx channel > (for read) and all the registers read/write descriptors in > command channel. > > Signed-off-by: Abhishek Sahu > --- > drivers/mtd/nand/qcom_nandc.c | 119 ++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 114 insertions(+), 5 deletions(-) > > diff --git a/drivers/mtd/nand/qcom_nandc.c b/drivers/mtd/nand/qcom_nandc.c > index f8d0bde..7042a65 100644 > --- a/drivers/mtd/nand/qcom_nandc.c > +++ b/drivers/mtd/nand/qcom_nandc.c > @@ -206,14 +206,22 @@ struct bam_transaction { > * This data type corresponds to the nand dma descriptor > * @list - list for desc_info > * @dir - DMA transfer direction > - * @sgl - sgl which will be used for single sgl dma descriptor > + * @sgl - sgl which will be used for single sgl dma descriptor. Only used by ADM > + * @bam_sgl - sgl which will be used for dma descriptor. Only used by BAM > + * @sgl_cnt - number of SGL in bam_sgl. Only used by BAM > * @dma_desc - low level dma engine descriptor > */ > struct desc_info { > struct list_head node; > > enum dma_data_direction dir; > - struct scatterlist sgl; > + union { > + struct scatterlist sgl; Can you make this adm_sgl instead for consistency? Also, please use only two tabs instead of one here for indentation. > + struct { > + struct scatterlist *bam_sgl; > + int sgl_cnt; > + }; > + }; > struct dma_async_tx_descriptor *dma_desc; > }; > > @@ -564,6 +572,68 @@ static void update_rw_regs(struct qcom_nand_host *host, int num_cw, bool read) > nandc_set_reg(nandc, NAND_EXEC_CMD, 1); > } > > +/* > + * Maps the scatter gather list for DMA transfer and forms the DMA descriptor > + * for BAM. This descriptor will be added in the NAND DMA descriptor queue > + * which will be submitted to DMA engine. > + */ > +static int prepare_bam_async_desc(struct qcom_nand_controller *nandc, > + struct dma_chan *chan, > + unsigned long flags) From what I gathered in patch #10, this would be called by prep_dma_desc_data_bam() and prep_dma_desc_command(). Can you rename these two to something like prep_bam_dma_desc_data() and prep_bam_dma_desc_cmd() > +{ > + struct desc_info *desc; > + struct scatterlist *sgl; > + unsigned int sgl_cnt; > + struct bam_transaction *bam_txn = nandc->bam_txn; > + enum dma_transfer_direction dir_eng; > + struct dma_async_tx_descriptor *dma_desc; > + > + desc = kzalloc(sizeof(*desc), GFP_KERNEL); > + if (!desc) > + return -ENOMEM; > + > + if (chan == nandc->cmd_chan) { > + sgl = &bam_txn->cmd_sgl[bam_txn->cmd_sgl_start]; > + sgl_cnt = bam_txn->cmd_sgl_pos - bam_txn->cmd_sgl_start; > + bam_txn->cmd_sgl_start = bam_txn->cmd_sgl_pos; > + dir_eng = DMA_MEM_TO_DEV; > + desc->dir = DMA_TO_DEVICE; > + } else if (chan == nandc->tx_chan) { > + sgl = &bam_txn->data_sg[bam_txn->tx_sgl_start]; > + sgl_cnt = bam_txn->tx_sgl_pos - bam_txn->tx_sgl_start; > + bam_txn->tx_sgl_start = bam_txn->tx_sgl_pos; > + dir_eng = DMA_MEM_TO_DEV; > + desc->dir = DMA_TO_DEVICE; > + } else { > + sgl = &bam_txn->data_sg[bam_txn->rx_sgl_start]; > + sgl_cnt = bam_txn->rx_sgl_pos - bam_txn->rx_sgl_start; > + bam_txn->rx_sgl_start = bam_txn->rx_sgl_pos; > + desc->dir = DMA_FROM_DEVICE; > + dir_eng = DMA_DEV_TO_MEM; > + } > + > + sg_mark_end(sgl + sgl_cnt - 1); > + dma_map_sg(nandc->dev, sgl, sgl_cnt, desc->dir); Is it safe to assume here that dma_map_sg won't return an error? > + > + desc->sgl_cnt = sgl_cnt; > + desc->bam_sgl = sgl; > + > + dma_desc = dmaengine_prep_slave_sg(chan, sgl, sgl_cnt, dir_eng, > + flags); > + > + if (!dma_desc) { > + dev_err(nandc->dev, "failure in prep desc\n"); > + kfree(desc); > + return -EINVAL; > + } > + > + desc->dma_desc = dma_desc; > + > + list_add_tail(&desc->node, &nandc->desc_list); > + > + return 0; > +} > + > static int prep_dma_desc(struct qcom_nand_controller *nandc, bool read, > int reg_off, const void *vaddr, int size, > bool flow_control) Could you rename this to prep_adm_dma_desc for consistency? > @@ -891,12 +961,44 @@ static int submit_descs(struct qcom_nand_controller *nandc) > { > struct desc_info *desc; > dma_cookie_t cookie = 0; > + struct bam_transaction *bam_txn = nandc->bam_txn; > + int r; > + > + if (nandc->dma_bam_enabled) { > + if (bam_txn->rx_sgl_pos - bam_txn->rx_sgl_start) { Using '>' instead of '-' here should be more legible. > + r = prepare_bam_async_desc(nandc, nandc->rx_chan, 0); > + if (r) > + return r; > + } > + > + if (bam_txn->tx_sgl_pos - bam_txn->tx_sgl_start) { > + r = prepare_bam_async_desc(nandc, nandc->tx_chan, > + DMA_PREP_INTERRUPT); > + if (r) > + return r; > + } > + > + if (bam_txn->cmd_sgl_pos - bam_txn->cmd_sgl_start) { > + r = prepare_bam_async_desc(nandc, nandc->cmd_chan, > + DMA_PREP_CMD); > + if (r) > + return r; > + } > + } > > list_for_each_entry(desc, &nandc->desc_list, node) > cookie = dmaengine_submit(desc->dma_desc); > > - if (dma_sync_wait(nandc->chan, cookie) != DMA_COMPLETE) > - return -ETIMEDOUT; > + if (nandc->dma_bam_enabled) { > + dma_async_issue_pending(nandc->tx_chan); > + dma_async_issue_pending(nandc->rx_chan); > + > + if (dma_sync_wait(nandc->cmd_chan, cookie) != DMA_COMPLETE) > + return -ETIMEDOUT; > + } else { > + if (dma_sync_wait(nandc->chan, cookie) != DMA_COMPLETE) > + return -ETIMEDOUT; > + } > > return 0; > } > @@ -907,7 +1009,14 @@ static void free_descs(struct qcom_nand_controller *nandc) > > list_for_each_entry_safe(desc, n, &nandc->desc_list, node) { > list_del(&desc->node); > - dma_unmap_sg(nandc->dev, &desc->sgl, 1, desc->dir); > + > + if (nandc->dma_bam_enabled) > + dma_unmap_sg(nandc->dev, desc->bam_sgl, > + desc->sgl_cnt, desc->dir); > + else > + dma_unmap_sg(nandc->dev, &desc->sgl, 1, > + desc->dir); > + > kfree(desc); > } > } > -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project