diff options
| author | Paul Walmsley <paul@pwsan.com> | 2011-10-06 20:50:33 (GMT) |
|---|---|---|
| committer | Chris Ball <cjb@laptop.org> | 2011-10-27 13:10:57 (GMT) |
| commit | 2bf22b39823c1d173dda31111a4eb2ce36daaf39 (patch) | |
| tree | 54575fedfd2b032c3113b55dea5e2fd5d0c7eb38 | |
| parent | b6ad726e3fe69e1ff3c3b2ad272ba3e4c376cd6a (diff) | |
| download | linux-2bf22b39823c1d173dda31111a4eb2ce36daaf39.tar.xz | |
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>
| -rw-r--r-- | drivers/mmc/card/block.c | 21 | ||||
| -rw-r--r-- | include/linux/mmc/host.h | 1 |
2 files changed, 15 insertions, 7 deletions
diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c index c0cb225..a1cb21f 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 diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index 16e9338..a3ac9c4 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -241,6 +241,7 @@ struct mmc_host { #define MMC_CAP2_BOOTPART_NOACC (1 << 0) /* Boot partition no access */ #define MMC_CAP2_CACHE_CTRL (1 << 1) /* Allow cache control */ #define MMC_CAP2_POWEROFF_NOTIFY (1 << 2) /* Notify poweroff supported */ +#define MMC_CAP2_NO_MULTI_READ (1 << 3) /* Multiblock reads don't work */ mmc_pm_flag_t pm_caps; /* supported pm features */ unsigned int power_notify_type; |