MX3 SoCs have a silicon bug which corrupts CRC calculation of multi-block transfers when connected SDIO peripheral doesn't drive the BUSY line as required by the specs.
One way to prevent this is to only allow 1-bit transfers. Another way is playing tricks with the DMA engine, but this isn't mainline yet. So for now, we live with the performance drawback of 1-bit transfers until a nicer solution is found. This patch introduces a new host controller callback 'init_card' which is for now only called from mmc_sdio_init_card(). Signed-off-by: Daniel Mack <[email protected]> Cc: Sascha Hauer <[email protected]> Cc: Dan Williams <[email protected]> Cc: Volker Ernst <[email protected]> Cc: Jiri Kosina <[email protected]> --- drivers/mmc/core/sdio.c | 6 ++++++ drivers/mmc/host/mxcmmc.c | 14 ++++++++++++++ include/linux/mmc/host.h | 3 +++ 3 files changed, 23 insertions(+), 0 deletions(-) diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c index 2dd4cfe..b9dee28 100644 --- a/drivers/mmc/core/sdio.c +++ b/drivers/mmc/core/sdio.c @@ -296,6 +296,12 @@ static int mmc_sdio_init_card(struct mmc_host *host, u32 ocr, card->type = MMC_TYPE_SDIO; /* + * Call the optional HC's init_card function to handle quirks. + */ + if (host->ops->init_card) + host->ops->init_card(host, card); + + /* * For native busses: set card RCA and quit open drain mode. */ if (!powered_resume && !mmc_host_is_spi(host)) { diff --git a/drivers/mmc/host/mxcmmc.c b/drivers/mmc/host/mxcmmc.c index 83a4545..f584c1b 100644 --- a/drivers/mmc/host/mxcmmc.c +++ b/drivers/mmc/host/mxcmmc.c @@ -708,11 +708,25 @@ static void mxcmci_enable_sdio_irq(struct mmc_host *mmc, int enable) spin_unlock_irqrestore(&host->lock, flags); } +static void mxcmci_init_card(struct mmc_host *host, struct mmc_card *card) +{ + /* + * MX3 SoCs have a silicon bug which corrupts CRC calculation of + * multi-block transfers when connected SDIO peripheral doesn't + * drive the BUSY line as required by the specs. + * One way to prevent this is to only allow 1-bit transfers. + */ + + if (cpu_is_mx3() && card->type == MMC_TYPE_SDIO) + host->caps &= ~MMC_CAP_4_BIT_DATA; +} + static const struct mmc_host_ops mxcmci_ops = { .request = mxcmci_request, .set_ios = mxcmci_set_ios, .get_ro = mxcmci_get_ro, .enable_sdio_irq = mxcmci_enable_sdio_irq, + .init_card = mxcmci_init_card, }; static int mxcmci_probe(struct platform_device *pdev) diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index 43eaf5c..3196c84 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -108,6 +108,9 @@ struct mmc_host_ops { int (*get_cd)(struct mmc_host *host); void (*enable_sdio_irq)(struct mmc_host *host, int enable); + + /* optional callback for HC quirks */ + void (*init_card)(struct mmc_host *host, struct mmc_card *card); }; struct mmc_card; -- 1.7.0 -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
