diff options
| author | Kyoungil Kim <ki0351.kim@samsung.com> | 2012-10-22 20:01:00 +0900 |
|---|---|---|
| committer | Chris Ball <cjb@laptop.org> | 2012-12-06 13:54:43 -0500 |
| commit | 968a64ea638bbd48839b41981ff50197f3412676 (patch) | |
| tree | a46f677245e219b03e24d4e7c0f0ce405e6b447d /drivers/mmc/core/sdio_ops.c | |
| parent | 8fee476b219d1869762d9ef5c189a0c85e919a4d (diff) | |
mmc: sdio: Use multiple scatter/gather list
Before this patch, we always used only single sg entry for SDIO transfer.
This patch switches to using multiple sg entries. In the case of dwmci,
it supports only up to 4KB size per single sg entry. So if we want to
transfer more than 4KB, we should send more than 1 command.
When we tested before applying this patch, it took around 335 us for
5K(5120) bytes transfer with dwmci controller. After applying this patch,
it takes 242 us for 5K bytes. So this patch makes around 38% performance
improvement for 5K bytes transfer. If the transfer size is bigger, then
the performance improvement ratio will be increased.
Signed-off-by: Kyoungil Kim <ki0351.kim@samsung.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
Diffstat (limited to 'drivers/mmc/core/sdio_ops.c')
| -rw-r--r-- | drivers/mmc/core/sdio_ops.c | 32 |
1 files changed, 28 insertions, 4 deletions
diff --git a/drivers/mmc/core/sdio_ops.c b/drivers/mmc/core/sdio_ops.c index d29e20630eed..62508b457c4f 100644 --- a/drivers/mmc/core/sdio_ops.c +++ b/drivers/mmc/core/sdio_ops.c @@ -124,7 +124,10 @@ int mmc_io_rw_extended(struct mmc_card *card, int write, unsigned fn, struct mmc_request mrq = {NULL}; struct mmc_command cmd = {0}; struct mmc_data data = {0}; - struct scatterlist sg; + struct scatterlist sg, *sg_ptr; + struct sg_table sgtable; + unsigned int nents, left_size, i; + unsigned int seg_size = card->host->max_seg_size; BUG_ON(!card); BUG_ON(fn > 7); @@ -152,15 +155,36 @@ int mmc_io_rw_extended(struct mmc_card *card, int write, unsigned fn, /* Code in host drivers/fwk assumes that "blocks" always is >=1 */ data.blocks = blocks ? blocks : 1; data.flags = write ? MMC_DATA_WRITE : MMC_DATA_READ; - data.sg = &sg; - data.sg_len = 1; - sg_init_one(&sg, buf, data.blksz * data.blocks); + left_size = data.blksz * data.blocks; + nents = (left_size - 1) / seg_size + 1; + if (nents > 1) { + if (sg_alloc_table(&sgtable, nents, GFP_KERNEL)) + return -ENOMEM; + + data.sg = sgtable.sgl; + data.sg_len = nents; + + for_each_sg(data.sg, sg_ptr, data.sg_len, i) { + sg_set_page(sg_ptr, virt_to_page(buf + (i * seg_size)), + min(seg_size, left_size), + offset_in_page(buf + (i * seg_size))); + left_size = left_size - seg_size; + } + } else { + data.sg = &sg; + data.sg_len = 1; + + sg_init_one(&sg, buf, left_size); + } mmc_set_data_timeout(&data, card); mmc_wait_for_req(card->host, &mrq); + if (nents > 1) + sg_free_table(&sgtable); + if (cmd.error) return cmd.error; if (data.error) |