Re: [RFC PATCH] mmc: sdio: rw extended, use a sg entry for each block

Le 07/09/2011 13:40, Nicolas Ferre :

While using io multiple blocks operations, change the way that sg is built: use one sg entry for each block instead of aggregating the whole buffer in a single sg entry. Using a single sg entry for a multiple block command may lead to misunderstanding between the sd/mmc and the DMA controllers. In fact, the knowledge of the block length will allow both controllers to optimize burst sizes on internal bus while dealing with those data.

Use a sg table to store start addresses of blocks within the data buffer.

Ping?

I add linaro-dev so maybe other people can be interested...

Signed-off-by: Nicolas Ferre nicolas.ferre@atmel.com

drivers/mmc/core/sdio_ops.c | 38 +++++++++++++++++++++++++++++--------- 1 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/drivers/mmc/core/sdio_ops.c b/drivers/mmc/core/sdio_ops.c index f087d87..aea6978 100644 --- a/drivers/mmc/core/sdio_ops.c +++ b/drivers/mmc/core/sdio_ops.c @@ -124,7 +124,7 @@ int mmc_io_rw_extended(struct mmc_card *card, int write, unsigned fn, struct mmc_request mrq = {0}; struct mmc_command cmd = {0}; struct mmc_data data = {0};

• struct scatterlist sg;

• struct sg_table sgt;

BUG_ON(!card); BUG_ON(fn > 7); @@ -144,24 +144,44 @@ int mmc_io_rw_extended(struct mmc_card *card, int write, unsigned fn, cmd.arg |= fn << 28; cmd.arg |= incr_addr ? 0x04000000 : 0x00000000; cmd.arg |= addr << 9;

• if (blocks == 1 && blksz <= 512)

• cmd.arg |= (blksz == 512) ? 0 : blksz;	/* byte mode */
  

• else

• cmd.arg |= 0x08000000 | blocks;		/* block mode */
  

• if (blocks == 1 && blksz <= 512) {

• /* byte mode */
  

• struct scatterlist sg;
  

• cmd.arg |= (blksz == 512) ? 0 : blksz;
  

• sg_init_one(&sg, buf, blksz * blocks);
  

• data.sg = &sg;
  

• data.sg_len = 1;
  

• } else {

• /* block mode */
  

• struct scatterlist *sg_ptr;
  

• int i;
  

• cmd.arg |= 0x08000000 | blocks;
  

• if (sg_alloc_table(&sgt, blocks, GFP_KERNEL))
  

• 	return -ENOMEM;
  

• for_each_sg(sgt.sgl, sg_ptr, sgt.nents, i) {
  

• 	sg_set_buf(sg_ptr, buf + i * blksz, blksz);
  

• }
  

• data.sg = sgt.sgl;
  

• data.sg_len = sgt.nents;
  

• }
• cmd.flags = MMC_RSP_SPI_R5 | MMC_RSP_R5 | MMC_CMD_ADTC;

data.blksz = blksz; data.blocks = blocks; data.flags = write ? MMC_DATA_WRITE : MMC_DATA_READ;

• data.sg = &sg;
• data.sg_len = 1;
• sg_init_one(&sg, buf, blksz * blocks);

mmc_set_data_timeout(&data, card); mmc_wait_for_req(card->host, &mrq);

• if (blocks != 1 || blksz > 512)

• sg_free_table(&sgt);
  

• if (cmd.error) return cmd.error; if (data.error)

Best regards,