Re: [PATCH v2] mmc: dw_mmc: Add support for pre_req and post_req

[Chris Ball <cjb@laptop.org>]

Hi,

Adding Will and James for their review/ACK.  Thanks,

- Chris.

On Thu, Jan 26 2012, Seungwon Jeon wrote:
> This patch implements pre_req and post_req in dw_mmc
> to support asynchronous mmc request.
>
> Signed-off-by: Seungwon Jeon <tgih.jun@samsung.com>
> ---
> Changes in v2:
> 	Consider system DMA case as well as IDMAC.
>
> NOTE:
>     Performance gains the following.
>     Sequential read and write improve 23% and 5% respectively.
>
>  drivers/mmc/host/dw_mmc.c |  129 +++++++++++++++++++++++++++++++++++---------
>  1 files changed, 102 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 0e34279..5c91acb 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -297,14 +297,24 @@ static void dw_mci_stop_dma(struct dw_mci *host)
>  }
>  
>  #ifdef CONFIG_MMC_DW_IDMAC
> +static int dw_mci_get_dma_dir(struct mmc_data *data)
> +{
> +	if (data->flags & MMC_DATA_WRITE)
> +		return DMA_TO_DEVICE;
> +	else
> +		return DMA_FROM_DEVICE;
> +}
> +
>  static void dw_mci_dma_cleanup(struct dw_mci *host)
>  {
>  	struct mmc_data *data = host->data;
>  
>  	if (data)
> -		dma_unmap_sg(&host->pdev->dev, data->sg, data->sg_len,
> -			     ((data->flags & MMC_DATA_WRITE)
> -			      ? DMA_TO_DEVICE : DMA_FROM_DEVICE));
> +		if (!data->host_cookie)
> +			dma_unmap_sg(&host->pdev->dev,
> +				     data->sg,
> +				     data->sg_len,
> +				     dw_mci_get_dma_dir(data));
>  }
>  
>  static void dw_mci_idmac_stop_dma(struct dw_mci *host)
> @@ -420,26 +430,15 @@ static int dw_mci_idmac_init(struct dw_mci *host)
>  	return 0;
>  }
>  
> -static 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,
> -	.cleanup = dw_mci_dma_cleanup,
> -};
> -#endif /* CONFIG_MMC_DW_IDMAC */
> -
> -static int dw_mci_submit_data_dma(struct dw_mci *host, struct mmc_data *data)
> +static int dw_mci_pre_dma_transfer(struct dw_mci *host,
> +				   struct mmc_data *data,
> +				   bool next)
>  {
>  	struct scatterlist *sg;
> -	unsigned int i, direction, sg_len;
> -	u32 temp;
> -
> -	host->using_dma = 0;
> +	unsigned int i, sg_len;
>  
> -	/* If we don't have a channel, we can't do DMA */
> -	if (!host->use_dma)
> -		return -ENODEV;
> +	if (!next && data->host_cookie)
> +		return data->host_cookie;
>  
>  	/*
>  	 * We don't do DMA on "complex" transfers, i.e. with
> @@ -448,6 +447,7 @@ static int dw_mci_submit_data_dma(struct dw_mci *host, struct mmc_data *data)
>  	 */
>  	if (data->blocks * data->blksz < DW_MCI_DMA_THRESHOLD)
>  		return -EINVAL;
> +
>  	if (data->blksz & 3)
>  		return -EINVAL;
>  
> @@ -456,15 +456,88 @@ static int dw_mci_submit_data_dma(struct dw_mci *host, struct mmc_data *data)
>  			return -EINVAL;
>  	}
>  
> -	host->using_dma = 1;
> +	sg_len = dma_map_sg(&host->pdev->dev,
> +			    data->sg,
> +			    data->sg_len,
> +			    dw_mci_get_dma_dir(data));
> +	if (sg_len == 0)
> +		return -EINVAL;
>  
> -	if (data->flags & MMC_DATA_READ)
> -		direction = DMA_FROM_DEVICE;
> -	else
> -		direction = DMA_TO_DEVICE;
> +	if (next)
> +		data->host_cookie = sg_len;
> +
> +	return sg_len;
> +}
> +
> +static 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,
> +	.cleanup = dw_mci_dma_cleanup,
> +};
> +#else
> +static int dw_mci_pre_dma_transfer(struct dw_mci *host,
> +				   struct mmc_data *data,
> +				   bool next)
> +{
> +	return -ENOSYS;
> +}
> +#endif /* CONFIG_MMC_DW_IDMAC */
> +
> +static void dw_mci_pre_req(struct mmc_host *mmc,
> +			   struct mmc_request *mrq,
> +			   bool is_first_req)
> +{
> +	struct dw_mci_slot *slot = mmc_priv(mmc);
> +	struct mmc_data *data = mrq->data;
> +
> +	if (!slot->host->use_dma || !data)
> +		return;
> +
> +	if (data->host_cookie) {
> +		data->host_cookie = 0;
> +		return;
> +	}
> +
> +	if (dw_mci_pre_dma_transfer(slot->host, mrq->data, 1) < 0)
> +		data->host_cookie = 0;
> +}
> +
> +static void dw_mci_post_req(struct mmc_host *mmc,
> +			    struct mmc_request *mrq,
> +			    int err)
> +{
> +	struct dw_mci_slot *slot = mmc_priv(mmc);
> +	struct mmc_data *data = mrq->data;
> +
> +	if (!slot->host->use_dma || !data)
> +		return;
> +
> +	if (data->host_cookie)
> +		dma_unmap_sg(&slot->host->pdev->dev,
> +				data->sg,
> +				data->sg_len,
> +				dw_mci_get_dma_dir(data));
> +	data->host_cookie = 0;
> +}
> +
> +static int dw_mci_submit_data_dma(struct dw_mci *host, struct mmc_data *data)
> +{
> +	int sg_len;
> +	u32 temp;
>  
> -	sg_len = dma_map_sg(&host->pdev->dev, data->sg, data->sg_len,
> -			    direction);
> +	host->using_dma = 0;
> +
> +	/* If we don't have a channel, we can't do DMA */
> +	if (!host->use_dma)
> +		return -ENODEV;
> +
> +	sg_len = dw_mci_pre_dma_transfer(host, data, 0);
> +	if (sg_len < 0)
> +		return sg_len;
> +
> +	host->using_dma = 1;
>  
>  	dev_vdbg(&host->pdev->dev,
>  		 "sd sg_cpu: %#lx sg_dma: %#lx sg_len: %d\n",
> @@ -795,6 +868,8 @@ static void dw_mci_enable_sdio_irq(struct mmc_host *mmc, int enb)
>  
>  static const struct mmc_host_ops dw_mci_ops = {
>  	.request		= dw_mci_request,
> +	.pre_req		= dw_mci_pre_req,
> +	.post_req		= dw_mci_post_req,
>  	.set_ios		= dw_mci_set_ios,
>  	.get_ro			= dw_mci_get_ro,
>  	.get_cd			= dw_mci_get_cd,

-- 
Chris Ball   <cjb@laptop.org>   <http://printf.net/>
One Laptop Per Child