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| author | Paul Walmsley <paul@pwsan.com> | 2011-10-06 14:50:33 -0600 |
|---|---|---|
| committer | Chris Ball <cjb@laptop.org> | 2011-10-27 09:10:57 -0400 |
| commit | 2bf22b39823c1d173dda31111a4eb2ce36daaf39 (patch) | |
| tree | 54575fedfd2b032c3113b55dea5e2fd5d0c7eb38 /drivers/mmc/card | |
| parent | b6ad726e3fe69e1ff3c3b2ad272ba3e4c376cd6a (diff) | |
| download | linux-2bf22b39823c1d173dda31111a4eb2ce36daaf39.tar.gz linux-2bf22b39823c1d173dda31111a4eb2ce36daaf39.tar.bz2 linux-2bf22b39823c1d173dda31111a4eb2ce36daaf39.zip | |
mmc: core: add workaround for controllers with broken multiblock reads
Due to hardware bugs, some MMC host controllers don't support
multiple-block reads[1]. To resolve, add a new MMC capability flag,
MMC_CAP2_NO_MULTI_READ, which can be set by affected host controller
drivers. When this capability is set, all reads will be issued one
sector at a time.
1. See for example Advisory 2.1.1.128 "MMC: Multiple Block Read
Operation Issue" in _OMAP3530/3525/3515/3503 Silicon Errata_
Revision F (October 2010) (SPRZ278F), available from
http://focus.ti.com/lit/er/sprz278f/sprz278f.pdf
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Dave Hylands <dhylands@gmail.com>
Tested-by: Steve Sakoman <sakoman@gmail.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
Diffstat (limited to 'drivers/mmc/card')
| -rw-r--r-- | drivers/mmc/card/block.c | 21 |
1 files changed, 14 insertions, 7 deletions
diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c index c0cb225bbb47..a1cb21f95302 100644 --- a/drivers/mmc/card/block.c +++ b/drivers/mmc/card/block.c @@ -1030,13 +1030,20 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq, if (brq->data.blocks > card->host->max_blk_count) brq->data.blocks = card->host->max_blk_count; - /* - * After a read error, we redo the request one sector at a time - * in order to accurately determine which sectors can be read - * successfully. - */ - if (disable_multi && brq->data.blocks > 1) - brq->data.blocks = 1; + if (brq->data.blocks > 1) { + /* + * After a read error, we redo the request one sector + * at a time in order to accurately determine which + * sectors can be read successfully. + */ + if (disable_multi) + brq->data.blocks = 1; + + /* Some controllers can't do multiblock reads due to hw bugs */ + if (card->host->caps2 & MMC_CAP2_NO_MULTI_READ && + rq_data_dir(req) == READ) + brq->data.blocks = 1; + } if (brq->data.blocks > 1 || do_rel_wr) { /* SPI multiblock writes terminate using a special |