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authorDaniel Mack <daniel@caiaq.de>2010-04-01 10:03:25 +0200
committerSascha Hauer <s.hauer@pengutronix.de>2010-04-14 09:18:07 +0200
commit3fcb027d7fd749569665d34a79ce2a8e00bc2ed6 (patch)
tree154b65062a5e2c0ff94c9463c8dfe7bfc905affd /drivers/mmc
parentf441b993101d4ee95222ccbaad1e0dd53ea90b64 (diff)
ARM: MXC: mxcmmc: work around a bug in the SDHC busy line handling
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 <daniel@caiaq.de> Cc: Sascha Hauer <s.hauer@pengutronix.de> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Volker Ernst <volker.ernst@txtr.com> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Michał Mirosław <mirqus@gmail.com> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Diffstat (limited to 'drivers/mmc')
-rw-r--r--drivers/mmc/core/sdio.c6
-rw-r--r--drivers/mmc/host/mxcmmc.c16
2 files changed, 22 insertions, 0 deletions
diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
index 2dd4cfe7ca1..b9dee28ee7d 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 51e880c8f19..2c53024ee43 100644
--- a/drivers/mmc/host/mxcmmc.c
+++ b/drivers/mmc/host/mxcmmc.c
@@ -724,11 +724,27 @@ 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;
+ else
+ 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)