2012/2/23 Seungwon Jeon <tgih....@samsung.com>: > Hi all, > > Even though 1MB is reserved for descriptor table in IDMAC, > the dw_mmc host driver is allowed to receive only maximum > 128KB block length in one request. This is caused by setting > improper max_blk_count. It needs to be e adjusted so that > descriptor table is used fully. > > It is found that the performance is improved with the increased the > max_blk_count. In my case, there is 82%(6%) improvement in sequential > write(read). Is there anybody who knows the reason about the old setting? > > Best regards, > Seungwon Jeon. > > Signed-off-by: Seungwon Jeon <tgih....@samsung.com> > --- > drivers/mmc/host/dw_mmc.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c > index bf3c9b4..af2b901 100644 > --- a/drivers/mmc/host/dw_mmc.c > +++ b/drivers/mmc/host/dw_mmc.c > @@ -1804,9 +1804,9 @@ static int __init dw_mci_init_slot(struct dw_mci *host, > unsigned int id) > #ifdef CONFIG_MMC_DW_IDMAC > mmc->max_segs = host->ring_size; > mmc->max_blk_size = 65536; > - mmc->max_blk_count = host->ring_size; > mmc->max_seg_size = 0x1000; > - mmc->max_req_size = mmc->max_seg_size * mmc->max_blk_count; > + mmc->max_req_size = mmc->max_seg_size * host->ring_size; > + mmc->max_blk_count = mmc->max_req_size / 512;
I am not sure this is correct, it seems like most drivers calculate max_req_size like this: mmc->max_req_size = mmc->max_blk_size * mmc->max_blk_count; And indeed in the external DMA case dw_mmc does that too. It should probably be safe to set max_seg_size to max_req_size too. > #else > mmc->max_segs = 64; > mmc->max_blk_size = 65536; /* BLKSIZ is 16 bits */ > -- > 1.7.0.4 > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
