Message-id: <55D6C4D4.8010005@samsung.com>
Date: Fri, 21 Aug 2015 15:27:32 +0900
From: Jaehoon Chung <jh80.chung@samsung.com>
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To: Shawn Lin <shawn.lin@rock-chips.com>, jh80.chung@samsung.com,
        ulf.hansson@linaro.org
Cc: Vineet.Gupta1@synopsys.com, Wei Xu <xuwei5@hisilicon.com>,
        Joachim Eastwood <manabian@gmail.com>,
        Alexey Brodkin <abrodkin@synopsys.com>, Kukjin Kim <kgene@kernel.org>,
        Krzysztof Kozlowski <k.kozlowski@samsung.com>,
        Russell King <linux@arm.linux.org.uk>,
        Zhangfei Gao <zhangfei.gao@linaro.org>, Jun Nie <jun.nie@linaro.org>,
        Ralf Baechle <ralf@linux-mips.org>,
        Govindraj Raja <govindraj.raja@imgtec.com>,
        Arnd Bergmann <arnd@arndb.de>, heiko@sntech.de, dianders@chromium.org,
        linux-samsung-soc@vger.kernel.org, linux-mips@linux-mips.org,
        linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-rockchip@lists.infradead.org, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, CPGS <cpgs@samsung.com>
Subject: Re: [RFC PATCH v6 1/9] mmc: dw_mmc: Add external dma interface support
References: <1440060204-26203-1-git-send-email-shawn.lin@rock-chips.com>
 <1440060233-26244-1-git-send-email-shawn.lin@rock-chips.com>
In-reply-to: <1440060233-26244-1-git-send-email-shawn.lin@rock-chips.com>
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Hi, Shawn.

Is this based on Ulf's repository?

On 08/20/2015 05:43 PM, Shawn Lin wrote:
> DesignWare MMC Controller can supports two types of DMA
> mode: external dma and internal dma. We get a RK312x platform
> integrated dw_mmc and ARM pl330 dma controller. This patch add
> edmac ops to support these platforms. I've tested it on RK31xx
> platform with edmac mode and RK3288 platform with idmac mode.
> 
> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
> 
> ---
> 
> Changes in v6:
> - add trans_mode condition for IDMAC initialization
>   suggested by Heiko
> - re-test my patch on rk3188 platform and update commit msg
> - update performance of pio vs edmac in cover letter
> 
> Changes in v5:
> - add the title of cover letter
> - fix typo of comment
> - add macro for reading HCON register
> - add "Acked-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>" for exynos_defconfig patch
> - add "Acked-by: Vineet Gupta <vgupta@synopsys.com>" for axs10x_defconfig patch
> - add "Acked-by: Govindraj Raja <govindraj.raja@imgtec.com>" and
>   "Acked-by: Ralf Baechle <ralf@linux-mips.org>" for pistachio_defconfig patch
> - add "Acked-by: Joachim Eastwood <manabian@gmail.com>" for lpc18xx_defconfig patch
> - add "Acked-by: Wei Xu <xuwei5@hisilicon.com>" for hisi_defconfig patch
> - rebase on "https://github.com/jh80chung/dw-mmc.git tags/dw-mmc-for-ulf-v4.2" for merging easily
> 
> Changes in v4:
> - remove "host->trans_mode" and use "host->use_dma" to indicate
>   transfer mode.
> - remove all bt-bindings' changes since we don't need new properities.
> - check transfer mode at runtime by reading HCON reg
> - spilt defconfig changes for each sub-architecture
> - fix the title of cover letter
> - reuse some code for reducing code size
> 
> Changes in v3:
> - choose transfer mode at runtime
> - remove all CONFIG_MMC_DW_IDMAC config option
> - add supports-idmac property for some platforms
> 
> Changes in v2:
> - Fix typo of dev_info msg
> - remove unused dmach from declaration of dw_mci_dma_slave
> 
>  drivers/mmc/host/Kconfig        |  11 +-
>  drivers/mmc/host/dw_mmc-pltfm.c |   2 +
>  drivers/mmc/host/dw_mmc.c       | 264 ++++++++++++++++++++++++++++++++--------
>  drivers/mmc/host/dw_mmc.h       |   5 +
>  include/linux/mmc/dw_mmc.h      |  27 +++-
>  5 files changed, 242 insertions(+), 67 deletions(-)
> 
> diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
> index 6a0f9c7..a86c0eb 100644
> --- a/drivers/mmc/host/Kconfig
> +++ b/drivers/mmc/host/Kconfig
> @@ -607,15 +607,7 @@ config MMC_DW
>  	help
>  	  This selects support for the Synopsys DesignWare Mobile Storage IP
>  	  block, this provides host support for SD and MMC interfaces, in both
> -	  PIO and external DMA modes.
> -
> -config MMC_DW_IDMAC
> -	bool "Internal DMAC interface"
> -	depends on MMC_DW
> -	help
> -	  This selects support for the internal DMAC block within the Synopsys
> -	  Designware Mobile Storage IP block. This disables the external DMA
> -	  interface.
> +	  PIO, internal DMA mode and external DMA modes.
>  
>  config MMC_DW_PLTFM
>  	tristate "Synopsys Designware MCI Support as platform device"
> @@ -644,7 +636,6 @@ config MMC_DW_K3
>  	tristate "K3 specific extensions for Synopsys DW Memory Card Interface"
>  	depends on MMC_DW
>  	select MMC_DW_PLTFM
> -	select MMC_DW_IDMAC
>  	help
>  	  This selects support for Hisilicon K3 SoC specific extensions to the
>  	  Synopsys DesignWare Memory Card Interface driver. Select this option
> diff --git a/drivers/mmc/host/dw_mmc-pltfm.c b/drivers/mmc/host/dw_mmc-pltfm.c
> index ec6dbcd..7e1d13b 100644
> --- a/drivers/mmc/host/dw_mmc-pltfm.c
> +++ b/drivers/mmc/host/dw_mmc-pltfm.c
> @@ -59,6 +59,8 @@ int dw_mci_pltfm_register(struct platform_device *pdev,
>  	host->pdata = pdev->dev.platform_data;
>  
>  	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	/* Get registers' physical base address */
> +	host->phy_regs = (void *)(regs->start);
>  	host->regs = devm_ioremap_resource(&pdev->dev, regs);
>  	if (IS_ERR(host->regs))
>  		return PTR_ERR(host->regs);

Is this board specific code? If so, separate the patch.

> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index fcbf552..f943619 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -56,7 +56,6 @@
>  #define DW_MCI_FREQ_MAX	200000000	/* unit: HZ */
>  #define DW_MCI_FREQ_MIN	400000		/* unit: HZ */
>  
> -#ifdef CONFIG_MMC_DW_IDMAC
>  #define IDMAC_INT_CLR		(SDMMC_IDMAC_INT_AI | SDMMC_IDMAC_INT_NI | \
>  				 SDMMC_IDMAC_INT_CES | SDMMC_IDMAC_INT_DU | \
>  				 SDMMC_IDMAC_INT_FBE | SDMMC_IDMAC_INT_RI | \
> @@ -102,7 +101,6 @@ struct idmac_desc {
>  
>  /* Each descriptor can transfer up to 4KB of data in chained mode */
>  #define DW_MCI_DESC_DATA_LENGTH	0x1000
> -#endif /* CONFIG_MMC_DW_IDMAC */
>  
>  static bool dw_mci_reset(struct dw_mci *host);
>  static bool dw_mci_ctrl_reset(struct dw_mci *host, u32 reset);
> @@ -407,7 +405,6 @@ static int dw_mci_get_dma_dir(struct mmc_data *data)
>  		return DMA_FROM_DEVICE;
>  }
>  
> -#ifdef CONFIG_MMC_DW_IDMAC
>  static void dw_mci_dma_cleanup(struct dw_mci *host)
>  {
>  	struct mmc_data *data = host->data;
> @@ -445,12 +442,21 @@ static void dw_mci_idmac_stop_dma(struct dw_mci *host)
>  	mci_writel(host, BMOD, temp);
>  }
>  
> -static void dw_mci_idmac_complete_dma(struct dw_mci *host)
> +static void dw_mci_dmac_complete_dma(void *arg)
>  {
> +	struct dw_mci *host = arg;
>  	struct mmc_data *data = host->data;
>  
>  	dev_vdbg(host->dev, "DMA complete\n");
>  
> +	if (host->use_dma == TRANS_MODE_EDMAC)
> +		if (data && (data->flags & MMC_DATA_READ))

Combine one condition.

> +			/* Invalidate cache after read */
> +			dma_sync_sg_for_cpu(mmc_dev(host->cur_slot->mmc),
> +					    data->sg,
> +					    data->sg_len,
> +					    DMA_FROM_DEVICE);
> +
>  	host->dma_ops->cleanup(host);
>  
>  	/*
> @@ -564,7 +570,7 @@ static void dw_mci_translate_sglist(struct dw_mci *host, struct mmc_data *data,
>  	wmb(); /* drain writebuffer */
>  }
>  
> -static void dw_mci_idmac_start_dma(struct dw_mci *host, unsigned int sg_len)
> +static int dw_mci_idmac_start_dma(struct dw_mci *host, unsigned int sg_len)
>  {
>  	u32 temp;
>  
> @@ -589,6 +595,8 @@ static void dw_mci_idmac_start_dma(struct dw_mci *host, unsigned int sg_len)
>  
>  	/* Start it running */
>  	mci_writel(host, PLDMND, 1);
> +
> +	return 0;
>  }
>  
>  static int dw_mci_idmac_init(struct dw_mci *host)
> @@ -669,10 +677,112 @@ static const struct dw_mci_dma_ops dw_mci_idmac_ops = {
>  	.init = dw_mci_idmac_init,
>  	.start = dw_mci_idmac_start_dma,
>  	.stop = dw_mci_idmac_stop_dma,
> -	.complete = dw_mci_idmac_complete_dma,
> +	.complete = dw_mci_dmac_complete_dma,
> +	.cleanup = dw_mci_dma_cleanup,
> +};
> +
> +static void dw_mci_edmac_stop_dma(struct dw_mci *host)
> +{
> +	dmaengine_terminate_all(host->dms->ch);
> +}
> +
> +static int dw_mci_edmac_start_dma(struct dw_mci *host,
> +					    unsigned int sg_len)
> +{
> +	struct dma_slave_config cfg;
> +	struct dma_async_tx_descriptor *desc = NULL;
> +	struct scatterlist *sgl = host->data->sg;
> +	const u32 mszs[] = {1, 4, 8, 16, 32, 64, 128, 256};
> +	u32 sg_elems = host->data->sg_len;
> +	u32 fifoth_val;
> +	u32 fifo_offset = host->fifo_reg - host->regs;
> +	int ret = 0;
> +
> +	/* Set external dma config: burst size, burst width */
> +	cfg.dst_addr = (dma_addr_t)(host->phy_regs + fifo_offset);

host->phy_regs is not assigned?

> +	cfg.src_addr = cfg.dst_addr;
> +	cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
> +	cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
> +
> +	/* Match burst msize with external dma config */
> +	fifoth_val = mci_readl(host, FIFOTH);
> +	cfg.dst_maxburst = mszs[(fifoth_val >> 28) & 0x7];
> +	cfg.src_maxburst = cfg.dst_maxburst;
> +
> +	if (host->data->flags & MMC_DATA_WRITE)
> +		cfg.direction = DMA_MEM_TO_DEV;
> +	else /* MMC_DATA_READ */
> +		cfg.direction = DMA_DEV_TO_MEM;
> +
> +	ret = dmaengine_slave_config(host->dms->ch, &cfg);
> +	if (ret) {
> +		dev_err(host->dev, "Failed to config edmac.\n");
> +		return -EBUSY;
> +	}
> +
> +	desc = dmaengine_prep_slave_sg(host->dms->ch, sgl,
> +				       sg_len, cfg.direction,
> +				       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> +	if (!desc) {
> +		dev_err(host->dev, "Can't prepare slave sg.\n");
> +		return -EBUSY;
> +	}
> +
> +	/* Set dw_mci_dmac_complete_dma as callback */
> +	desc->callback = dw_mci_dmac_complete_dma;
> +	desc->callback_param = (void *)host;
> +	dmaengine_submit(desc);
> +
> +	/* Flush cache before write */
> +	if (host->data->flags & MMC_DATA_WRITE)
> +		dma_sync_sg_for_device(mmc_dev(host->cur_slot->mmc), sgl,
> +				       sg_elems, DMA_TO_DEVICE);
> +
> +	dma_async_issue_pending(host->dms->ch);
> +
> +	return 0;
> +}
> +
> +static int dw_mci_edmac_init(struct dw_mci *host)
> +{
> +	/* Request external dma channel */
> +	host->dms = kzalloc(sizeof(struct dw_mci_dma_slave), GFP_KERNEL);
> +	if (!host->dms)
> +		return -ENOMEM;
> +
> +	host->dms->ch = dma_request_slave_channel(host->dev, "rx-tx");
> +	if (!host->dms->ch) {
> +		dev_err(host->dev,
> +			"Failed to get external DMA channel %d\n",
> +			host->dms->ch->chan_id);
> +		kfree(host->dms);
> +		host->dms = NULL;
> +		return -ENXIO;
> +	}
> +
> +	return 0;
> +}
> +
> +static void dw_mci_edmac_exit(struct dw_mci *host)
> +{
> +	if (host->dms) {
> +		if (host->dms->ch) {
> +			dma_release_channel(host->dms->ch);
> +			host->dms->ch = NULL;
> +		}
> +		kfree(host->dms);
> +		host->dms = NULL;
> +	}
> +}
> +
> +static const struct dw_mci_dma_ops dw_mci_edmac_ops = {
> +	.init = dw_mci_edmac_init,
> +	.exit = dw_mci_edmac_exit,
> +	.start = dw_mci_edmac_start_dma,
> +	.stop = dw_mci_edmac_stop_dma,
> +	.complete = dw_mci_dmac_complete_dma,
>  	.cleanup = dw_mci_dma_cleanup,
>  };
> -#endif /* CONFIG_MMC_DW_IDMAC */
>  
>  static int dw_mci_pre_dma_transfer(struct dw_mci *host,
>  				   struct mmc_data *data,
> @@ -752,7 +862,6 @@ static void dw_mci_post_req(struct mmc_host *mmc,
>  
>  static void dw_mci_adjust_fifoth(struct dw_mci *host, struct mmc_data *data)
>  {
> -#ifdef CONFIG_MMC_DW_IDMAC
>  	unsigned int blksz = data->blksz;
>  	const u32 mszs[] = {1, 4, 8, 16, 32, 64, 128, 256};
>  	u32 fifo_width = 1 << host->data_shift;
> @@ -760,6 +869,10 @@ static void dw_mci_adjust_fifoth(struct dw_mci *host, struct mmc_data *data)
>  	u32 msize = 0, rx_wmark = 1, tx_wmark, tx_wmark_invers;
>  	int idx = ARRAY_SIZE(mszs) - 1;
>  
> +	/* pio should ship this scenario */
> +	if (!host->use_dma)
> +		return;
> +
>  	tx_wmark = (host->fifo_depth) / 2;
>  	tx_wmark_invers = host->fifo_depth - tx_wmark;
>  
> @@ -788,7 +901,6 @@ static void dw_mci_adjust_fifoth(struct dw_mci *host, struct mmc_data *data)
>  done:
>  	fifoth_val = SDMMC_SET_FIFOTH(msize, rx_wmark, tx_wmark);
>  	mci_writel(host, FIFOTH, fifoth_val);
> -#endif
>  }
>  
>  static void dw_mci_ctrl_rd_thld(struct dw_mci *host, struct mmc_data *data)
> @@ -850,10 +962,12 @@ static int dw_mci_submit_data_dma(struct dw_mci *host, struct mmc_data *data)
>  
>  	host->using_dma = 1;
>  
> -	dev_vdbg(host->dev,
> -		 "sd sg_cpu: %#lx sg_dma: %#lx sg_len: %d\n",
> -		 (unsigned long)host->sg_cpu, (unsigned long)host->sg_dma,
> -		 sg_len);
> +	if (host->use_dma == TRANS_MODE_IDMAC)
> +		dev_vdbg(host->dev,
> +			 "sd sg_cpu: %#lx sg_dma: %#lx sg_len: %d\n",
> +			 (unsigned long)host->sg_cpu,
> +			 (unsigned long)host->sg_dma,
> +			 sg_len);
>  
>  	/*
>  	 * Decide the MSIZE and RX/TX Watermark.
> @@ -875,7 +989,11 @@ static int dw_mci_submit_data_dma(struct dw_mci *host, struct mmc_data *data)
>  	mci_writel(host, INTMASK, temp);
>  	spin_unlock_irqrestore(&host->irq_lock, irqflags);
>  
> -	host->dma_ops->start(host, sg_len);
> +	if (host->dma_ops->start(host, sg_len)) {
> +		/* We can't do DMA */
> +		dev_err(host->dev, "%s: failed to start DMA.\n", __func__);
> +		return -ENODEV;
> +	}
>  
>  	return 0;
>  }
> @@ -2343,15 +2461,17 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id)
>  
>  	}
>  
> -#ifdef CONFIG_MMC_DW_IDMAC
> -	/* Handle DMA interrupts */
> +	if (host->use_dma != TRANS_MODE_IDMAC)
> +		return IRQ_HANDLED;
> +
> +	/* Handle IDMA interrupts */
>  	if (host->dma_64bit_address == 1) {
>  		pending = mci_readl(host, IDSTS64);
>  		if (pending & (SDMMC_IDMAC_INT_TI | SDMMC_IDMAC_INT_RI)) {
>  			mci_writel(host, IDSTS64, SDMMC_IDMAC_INT_TI |
>  							SDMMC_IDMAC_INT_RI);
>  			mci_writel(host, IDSTS64, SDMMC_IDMAC_INT_NI);
> -			host->dma_ops->complete(host);
> +			host->dma_ops->complete((void *)host);
>  		}
>  	} else {
>  		pending = mci_readl(host, IDSTS);
> @@ -2359,10 +2479,9 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id)
>  			mci_writel(host, IDSTS, SDMMC_IDMAC_INT_TI |
>  							SDMMC_IDMAC_INT_RI);
>  			mci_writel(host, IDSTS, SDMMC_IDMAC_INT_NI);
> -			host->dma_ops->complete(host);
> +			host->dma_ops->complete((void *)host);
>  		}
>  	}
> -#endif
>  
>  	return IRQ_HANDLED;
>  }
> @@ -2471,13 +2590,21 @@ static int dw_mci_init_slot(struct dw_mci *host, unsigned int id)
>  		goto err_host_allocated;
>  
>  	/* Useful defaults if platform data is unset. */
> -	if (host->use_dma) {
> +	if (host->use_dma == TRANS_MODE_IDMAC) {
>  		mmc->max_segs = host->ring_size;
>  		mmc->max_blk_size = 65536;
>  		mmc->max_seg_size = 0x1000;
>  		mmc->max_req_size = mmc->max_seg_size * host->ring_size;
>  		mmc->max_blk_count = mmc->max_req_size / 512;
> +	} else if (host->use_dma == TRANS_MODE_EDMAC) {
> +			mmc->max_segs = 64;
> +			mmc->max_blk_size = 65536;
> +			mmc->max_blk_count = 65535;
> +			mmc->max_req_size =
> +					mmc->max_blk_size * mmc->max_blk_count;
> +			mmc->max_seg_size = mmc->max_req_size;

Fix the indention

>  	} else {
> +		/* TRANS_MODE_PIO */
>  		mmc->max_segs = 64;
>  		mmc->max_blk_size = 65536; /* BLKSIZ is 16 bits */
>  		mmc->max_blk_count = 512;
> @@ -2517,35 +2644,66 @@ static void dw_mci_cleanup_slot(struct dw_mci_slot *slot, unsigned int id)
>  static void dw_mci_init_dma(struct dw_mci *host)
>  {
>  	int addr_config;
> -	/* Check ADDR_CONFIG bit in HCON to find IDMAC address bus width */
> -	addr_config = (mci_readl(host, HCON) >> 27) & 0x01;
> -
> -	if (addr_config == 1) {
> -		/* host supports IDMAC in 64-bit address mode */
> -		host->dma_64bit_address = 1;
> -		dev_info(host->dev, "IDMAC supports 64-bit address mode.\n");
> -		if (!dma_set_mask(host->dev, DMA_BIT_MASK(64)))
> -			dma_set_coherent_mask(host->dev, DMA_BIT_MASK(64));
> -	} else {
> -		/* host supports IDMAC in 32-bit address mode */
> -		host->dma_64bit_address = 0;
> -		dev_info(host->dev, "IDMAC supports 32-bit address mode.\n");
> -	}
> +	int trans_mode;
> +	struct device *dev = host->dev;
> +	struct device_node *np = dev->of_node;
>  
> -	/* Alloc memory for sg translation */
> -	host->sg_cpu = dmam_alloc_coherent(host->dev, PAGE_SIZE,
> -					  &host->sg_dma, GFP_KERNEL);
> -	if (!host->sg_cpu) {
> -		dev_err(host->dev, "%s: could not alloc DMA memory\n",
> -			__func__);
> +	/* Check tansfer mode */
> +	trans_mode = SDMMC_GET_TRANS_MODE(mci_readl(host, HCON));
> +	if (trans_mode == 0) {
> +		trans_mode = TRANS_MODE_IDMAC;
> +	} else if (trans_mode == 1 || trans_mode == 2) {
> +		trans_mode = TRANS_MODE_EDMAC;
> +	} else {
> +		trans_mode = TRANS_MODE_PIO;

what are trans_mode "0, 1, 2"?
(00 - none) is NO-DMA interface, isn't? is it IDMAC mode?

>  		goto no_dma;
>  	}
>  
>  	/* Determine which DMA interface to use */
> -#ifdef CONFIG_MMC_DW_IDMAC
> -	host->dma_ops = &dw_mci_idmac_ops;
> -	dev_info(host->dev, "Using internal DMA controller.\n");
> -#endif
> +	if (trans_mode == TRANS_MODE_IDMAC) {
> +		/*
> +		* Check ADDR_CONFIG bit in HCON to find
> +		* IDMAC address bus width
> +		*/
> +		addr_config = SDMMC_GET_ADDR_CONFIG(mci_readl(host, HCON));
> +
> +		if (addr_config == 1) {
> +			/* host supports IDMAC in 64-bit address mode */
> +			host->dma_64bit_address = 1;
> +			dev_info(host->dev,
> +				 "IDMAC supports 64-bit address mode.\n");
> +			if (!dma_set_mask(host->dev, DMA_BIT_MASK(64)))
> +				dma_set_coherent_mask(host->dev,
> +						      DMA_BIT_MASK(64));
> +		} else {
> +			/* host supports IDMAC in 32-bit address mode */
> +			host->dma_64bit_address = 0;
> +			dev_info(host->dev,
> +				 "IDMAC supports 32-bit address mode.\n");
> +		}
> +
> +		/* Alloc memory for sg translation */
> +		host->sg_cpu = dmam_alloc_coherent(host->dev, PAGE_SIZE,
> +						   &host->sg_dma, GFP_KERNEL);
> +		if (!host->sg_cpu) {
> +			dev_err(host->dev,
> +				"%s: could not alloc DMA memory\n",
> +				__func__);
> +			goto no_dma;
> +		}
> +
> +		host->dma_ops = &dw_mci_idmac_ops;
> +		dev_info(host->dev, "Using internal DMA controller.\n");
> +	} else {
> +		/* TRANS_MODE_EDMAC: check dma bindings again */
> +		if ((of_property_count_strings(np, "dma-names") < 0) ||
> +		    (!of_find_property(np, "dmas", NULL))) {
> +			trans_mode = TRANS_MODE_PIO;
> +			goto no_dma;
> +		}
> +		host->dma_ops = &dw_mci_edmac_ops;
> +		dev_info(host->dev, "Using external DMA controller.\n");
> +	}
>  
>  	if (!host->dma_ops)
>  		goto no_dma;
> @@ -2562,12 +2720,12 @@ static void dw_mci_init_dma(struct dw_mci *host)
>  		goto no_dma;
>  	}
>  
> -	host->use_dma = 1;
> +	host->use_dma = trans_mode;

Also confuse, if trans_mode is assigned host->use_dma, can mode value be directly assigned to host->use_dma?

trans_mode = TRAMS_MODE_PIO;
host->use_dma = trans_mode;

-> host->use_dma = TRAMS_MODE_PIO;

Then trans_mode can be removed.

>  	return;
>  
>  no_dma:
>  	dev_info(host->dev, "Using PIO mode.\n");
> -	host->use_dma = 0;
> +	host->use_dma = trans_mode;
>  }
>  
>  static bool dw_mci_ctrl_reset(struct dw_mci *host, u32 reset)
> @@ -2650,10 +2808,9 @@ static bool dw_mci_reset(struct dw_mci *host)
>  		}
>  	}
>  
> -#if IS_ENABLED(CONFIG_MMC_DW_IDMAC)
> -	/* It is also recommended that we reset and reprogram idmac */
> -	dw_mci_idmac_reset(host);
> -#endif
> +	if (host->use_dma == TRANS_MODE_IDMAC)
> +		/* It is also recommended that we reset and reprogram idmac */
> +		dw_mci_idmac_reset(host);
>  
>  	ret = true;
>  
> @@ -2890,7 +3047,7 @@ int dw_mci_probe(struct dw_mci *host)
>  	 * Get the host data width - this assumes that HCON has been set with
>  	 * the correct values.
>  	 */
> -	i = (mci_readl(host, HCON) >> 7) & 0x7;
> +	i = SDMMC_GET_HDATA_WIDTH(mci_readl(host, HCON));

This is not related with supporting external dma interface.
Separate this.

>  	if (!i) {
>  		host->push_data = dw_mci_push_data16;
>  		host->pull_data = dw_mci_pull_data16;
> @@ -2972,7 +3129,7 @@ int dw_mci_probe(struct dw_mci *host)
>  	if (host->pdata->num_slots)
>  		host->num_slots = host->pdata->num_slots;
>  	else
> -		host->num_slots = ((mci_readl(host, HCON) >> 1) & 0x1F) + 1;
> +		host->num_slots = SDMMC_GET_SLOT_NUM(mci_readl(host, HCON));

Ditto. (with above.)

>  
>  	/*
>  	 * Enable interrupts for command done, data over, data empty,
> @@ -3067,6 +3224,9 @@ EXPORT_SYMBOL(dw_mci_remove);
>   */
>  int dw_mci_suspend(struct dw_mci *host)
>  {
> +	if (host->use_dma && host->dma_ops->exit)
> +		host->dma_ops->exit(host);
> +
>  	return 0;
>  }
>  EXPORT_SYMBOL(dw_mci_suspend);
> diff --git a/drivers/mmc/host/dw_mmc.h b/drivers/mmc/host/dw_mmc.h
> index 8ce4674..c453e94 100644
> --- a/drivers/mmc/host/dw_mmc.h
> +++ b/drivers/mmc/host/dw_mmc.h
> @@ -148,6 +148,11 @@
>  #define SDMMC_SET_FIFOTH(m, r, t)	(((m) & 0x7) << 28 | \
>  					 ((r) & 0xFFF) << 16 | \
>  					 ((t) & 0xFFF))
> +/* HCON register defines */
> +#define SDMMC_GET_SLOT_NUM(x)		((((x)>>1) & 0x1F) + 1)
> +#define SDMMC_GET_HDATA_WIDTH(x)	(((x)>>7) & 0x7)
> +#define SDMMC_GET_TRANS_MODE(x)		(((x)>>16) & 0x3)
> +#define SDMMC_GET_ADDR_CONFIG(x)	(((x)>>27) & 0x1)
>  /* Internal DMAC interrupt defines */
>  #define SDMMC_IDMAC_INT_AI		BIT(9)
>  #define SDMMC_IDMAC_INT_NI		BIT(8)
> diff --git a/include/linux/mmc/dw_mmc.h b/include/linux/mmc/dw_mmc.h
> index c846f42..6a2b83c 100644
> --- a/include/linux/mmc/dw_mmc.h
> +++ b/include/linux/mmc/dw_mmc.h
> @@ -16,6 +16,7 @@
>  
>  #include <linux/scatterlist.h>
>  #include <linux/mmc/core.h>
> +#include <linux/dmaengine.h>
>  
>  #define MAX_MCI_SLOTS	2
>  
> @@ -40,6 +41,17 @@ enum {
>  
>  struct mmc_data;
>  
> +enum {
> +	TRANS_MODE_PIO = 0,
> +	TRANS_MODE_IDMAC,
> +	TRANS_MODE_EDMAC
> +};
> +
> +struct dw_mci_dma_slave {
> +	struct dma_chan *ch;
> +	enum dma_transfer_direction direction;
> +};
> +
>  /**
>   * struct dw_mci - MMC controller state shared between all slots
>   * @lock: Spinlock protecting the queue and associated data.
> @@ -154,11 +166,16 @@ struct dw_mci {
>  	dma_addr_t		sg_dma;
>  	void			*sg_cpu;
>  	const struct dw_mci_dma_ops	*dma_ops;
> -#ifdef CONFIG_MMC_DW_IDMAC
> +	/* For idmac */
>  	unsigned int		ring_size;
> -#else
> +
> +	/* For edmac */
> +	struct dw_mci_dma_slave *dms;
> +	/* Registers's physical base address */
> +	void                    *phy_regs;
> +
>  	struct dw_mci_dma_data	*dma_data;
> -#endif
> +

On ulf's repository, this point should be conflicted.

Best Regards,
Jaehoon Chung

>  	u32			cmd_status;
>  	u32			data_status;
>  	u32			stop_cmdr;
> @@ -212,8 +229,8 @@ struct dw_mci {
>  struct dw_mci_dma_ops {
>  	/* DMA Ops */
>  	int (*init)(struct dw_mci *host);
> -	void (*start)(struct dw_mci *host, unsigned int sg_len);
> -	void (*complete)(struct dw_mci *host);
> +	int (*start)(struct dw_mci *host, unsigned int sg_len);
> +	void (*complete)(void *host);
>  	void (*stop)(struct dw_mci *host);
>  	void (*cleanup)(struct dw_mci *host);
>  	void (*exit)(struct dw_mci *host);
> 

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