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Message-ID: <CAPDyKFo4q+YWDgezZPqAHet0sBPE5WvnZzm00MHdf-+jZAY93Q@mail.gmail.com>
Date: Tue, 12 Aug 2014 18:22:04 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Apelete Seketeli <apelete@...eteli.net>
Cc: Chris Ball <chris@...ntf.net>,
H Hartley Sweeten <hsweeten@...ionengravers.com>,
Lars-Peter Clausen <lars@...afoo.de>,
Wei Yongjun <yongjun_wei@...ndmicro.com.cn>,
Alex Smith <alex.smith@...tec.com>,
Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
linux-mmc <linux-mmc@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 2/2] mmc: jz4740: prepare next dma transfer in parallel
with current transfer
On 21 July 2014 06:37, Apelete Seketeli <apelete@...eteli.net> wrote:
> Make use of the MMC asynchronous request capability to prepare the
> next DMA transfer request in parallel with the current transfer.
> This is done by adding pre-request and post-request callbacks that are
> used by the MMC framework during an active data transfer.
>
> It should help reduce the impact of DMA preparation overhead on the SD
> card performance.
>
> Signed-off-by: Apelete Seketeli <apelete@...eteli.net>
Thanks! Queued for 3.18.
Kind regards
Uffe
> ---
> drivers/mmc/host/jz4740_mmc.c | 138 ++++++++++++++++++++++++++++++++++-------
> 1 file changed, 116 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/mmc/host/jz4740_mmc.c b/drivers/mmc/host/jz4740_mmc.c
> index 049b133..14738cd 100644
> --- a/drivers/mmc/host/jz4740_mmc.c
> +++ b/drivers/mmc/host/jz4740_mmc.c
> @@ -114,6 +114,11 @@ enum jz4740_mmc_state {
> JZ4740_MMC_STATE_DONE,
> };
>
> +struct jz4740_mmc_host_next {
> + int sg_len;
> + s32 cookie;
> +};
> +
> struct jz4740_mmc_host {
> struct mmc_host *mmc;
> struct platform_device *pdev;
> @@ -143,6 +148,7 @@ struct jz4740_mmc_host {
> /* DMA support */
> struct dma_chan *dma_rx;
> struct dma_chan *dma_tx;
> + struct jz4740_mmc_host_next next_data;
> bool use_dma;
> int sg_len;
>
> @@ -184,6 +190,9 @@ static int jz4740_mmc_acquire_dma_channels(struct jz4740_mmc_host *host)
> goto free_master_write;
> }
>
> + /* Initialize DMA pre request cookie */
> + host->next_data.cookie = 1;
> +
> return 0;
>
> free_master_write:
> @@ -196,23 +205,72 @@ static inline int jz4740_mmc_get_dma_dir(struct mmc_data *data)
> return (data->flags & MMC_DATA_READ) ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
> }
>
> +static inline struct dma_chan *jz4740_mmc_get_dma_chan(struct jz4740_mmc_host *host,
> + struct mmc_data *data)
> +{
> + return (data->flags & MMC_DATA_READ) ? host->dma_rx : host->dma_tx;
> +}
> +
> static void jz4740_mmc_dma_unmap(struct jz4740_mmc_host *host,
> struct mmc_data *data)
> {
> - struct dma_chan *chan;
> + struct dma_chan *chan = jz4740_mmc_get_dma_chan(host, data);
> enum dma_data_direction dir = jz4740_mmc_get_dma_dir(data);
>
> - if (dir == DMA_TO_DEVICE)
> - chan = host->dma_tx;
> - else
> - chan = host->dma_rx;
> -
> dma_unmap_sg(chan->device->dev, data->sg, data->sg_len, dir);
> }
>
> +/* Prepares DMA data for current/next transfer, returns non-zero on failure */
> +static int jz4740_mmc_prepare_dma_data(struct jz4740_mmc_host *host,
> + struct mmc_data *data,
> + struct jz4740_mmc_host_next *next,
> + struct dma_chan *chan)
> +{
> + struct jz4740_mmc_host_next *next_data = &host->next_data;
> + enum dma_data_direction dir = jz4740_mmc_get_dma_dir(data);
> + int sg_len;
> +
> + if (!next && data->host_cookie &&
> + data->host_cookie != host->next_data.cookie) {
> + dev_warn(mmc_dev(host->mmc),
> + "[%s] invalid cookie: data->host_cookie %d host->next_data.cookie %d\n",
> + __func__,
> + data->host_cookie,
> + host->next_data.cookie);
> + data->host_cookie = 0;
> + }
> +
> + /* Check if next job is already prepared */
> + if (next || data->host_cookie != host->next_data.cookie) {
> + sg_len = dma_map_sg(chan->device->dev,
> + data->sg,
> + data->sg_len,
> + dir);
> +
> + } else {
> + sg_len = next_data->sg_len;
> + next_data->sg_len = 0;
> + }
> +
> + if (sg_len <= 0) {
> + dev_err(mmc_dev(host->mmc),
> + "Failed to map scatterlist for DMA operation\n");
> + return -EINVAL;
> + }
> +
> + if (next) {
> + next->sg_len = sg_len;
> + data->host_cookie = ++next->cookie < 0 ? 1 : next->cookie;
> + } else
> + host->sg_len = sg_len;
> +
> + return 0;
> +}
> +
> static int jz4740_mmc_start_dma_transfer(struct jz4740_mmc_host *host,
> struct mmc_data *data)
> {
> + int ret;
> struct dma_chan *chan;
> struct dma_async_tx_descriptor *desc;
> struct dma_slave_config conf = {
> @@ -221,9 +279,8 @@ static int jz4740_mmc_start_dma_transfer(struct jz4740_mmc_host *host,
> .src_maxburst = JZ4740_MMC_FIFO_HALF_SIZE,
> .dst_maxburst = JZ4740_MMC_FIFO_HALF_SIZE,
> };
> - enum dma_data_direction dir = jz4740_mmc_get_dma_dir(data);
>
> - if (dir == DMA_TO_DEVICE) {
> + if (data->flags & MMC_DATA_WRITE) {
> conf.direction = DMA_MEM_TO_DEV;
> conf.dst_addr = host->mem_res->start + JZ_REG_MMC_TXFIFO;
> conf.slave_id = JZ4740_DMA_TYPE_MMC_TRANSMIT;
> @@ -235,16 +292,9 @@ static int jz4740_mmc_start_dma_transfer(struct jz4740_mmc_host *host,
> chan = host->dma_rx;
> }
>
> - host->sg_len = dma_map_sg(chan->device->dev,
> - data->sg,
> - data->sg_len,
> - dir);
> -
> - if (host->sg_len == 0) {
> - dev_err(mmc_dev(host->mmc),
> - "Failed to map scatterlist for DMA operation\n");
> - return -EINVAL;
> - }
> + ret = jz4740_mmc_prepare_dma_data(host, data, NULL, chan);
> + if (ret)
> + return ret;
>
> dmaengine_slave_config(chan, &conf);
> desc = dmaengine_prep_slave_sg(chan,
> @@ -269,6 +319,43 @@ dma_unmap:
> return -ENOMEM;
> }
>
> +static void jz4740_mmc_pre_request(struct mmc_host *mmc,
> + struct mmc_request *mrq,
> + bool is_first_req)
> +{
> + struct jz4740_mmc_host *host = mmc_priv(mmc);
> + struct mmc_data *data = mrq->data;
> + struct jz4740_mmc_host_next *next_data = &host->next_data;
> +
> + BUG_ON(data->host_cookie);
> +
> + if (host->use_dma) {
> + struct dma_chan *chan = jz4740_mmc_get_dma_chan(host, data);
> +
> + if (jz4740_mmc_prepare_dma_data(host, data, next_data, chan))
> + data->host_cookie = 0;
> + }
> +}
> +
> +static void jz4740_mmc_post_request(struct mmc_host *mmc,
> + struct mmc_request *mrq,
> + int err)
> +{
> + struct jz4740_mmc_host *host = mmc_priv(mmc);
> + struct mmc_data *data = mrq->data;
> +
> + if (host->use_dma && data->host_cookie) {
> + jz4740_mmc_dma_unmap(host, data);
> + data->host_cookie = 0;
> + }
> +
> + if (err) {
> + struct dma_chan *chan = jz4740_mmc_get_dma_chan(host, data);
> +
> + dmaengine_terminate_all(chan);
> + }
> +}
> +
> /*----------------------------------------------------------------------------*/
>
> static void jz4740_mmc_set_irq_enabled(struct jz4740_mmc_host *host,
> @@ -627,14 +714,19 @@ static irqreturn_t jz_mmc_irq_worker(int irq, void *devid)
>
> case JZ4740_MMC_STATE_TRANSFER_DATA:
> if (host->use_dma) {
> - /* Use DMA if enabled, data transfer direction was
> - * defined before in jz_mmc_prepare_data_transfer().
> + /* Use DMA if enabled.
> + * Data transfer direction is defined later by
> + * relying on data flags in
> + * jz4740_mmc_prepare_dma_data() and
> + * jz4740_mmc_start_dma_transfer().
> */
> timeout = jz4740_mmc_start_dma_transfer(host, data);
> data->bytes_xfered = data->blocks * data->blksz;
> } else if (data->flags & MMC_DATA_READ)
> - /* If DMA is not enabled, rely on data flags
> - * to establish data transfer direction.
> + /* Use PIO if DMA is not enabled.
> + * Data transfer direction was defined before
> + * by relying on data flags in
> + * jz_mmc_prepare_data_transfer().
> */
> timeout = jz4740_mmc_read_data(host, data);
> else
> @@ -809,6 +901,8 @@ static void jz4740_mmc_enable_sdio_irq(struct mmc_host *mmc, int enable)
>
> static const struct mmc_host_ops jz4740_mmc_ops = {
> .request = jz4740_mmc_request,
> + .pre_req = jz4740_mmc_pre_request,
> + .post_req = jz4740_mmc_post_request,
> .set_ios = jz4740_mmc_set_ios,
> .get_ro = mmc_gpio_get_ro,
> .get_cd = mmc_gpio_get_cd,
> --
> 1.7.10.4
>
--
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