From 3fcb027d7fd749569665d34a79ce2a8e00bc2ed6 Mon Sep 17 00:00:00 2001
From: Daniel Mack <daniel@caiaq.de>
Date: Thu, 1 Apr 2010 10:03:25 +0200
Subject: [PATCH] ARM: MXC: mxcmmc: work around a bug in the SDHC busy line
handling
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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: MichaÅ MirosÅaw <mirqus@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
drivers/mmc/core/sdio.c | 6 ++++++
drivers/mmc/host/mxcmmc.c | 16 ++++++++++++++++
include/linux/mmc/host.h | 3 +++
3 files changed, 25 insertions(+)
diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
index 2dd4cfe7ca17..b9dee28ee7d0 100644
--- a/drivers/mmc/core/sdio.c
+++ b/drivers/mmc/core/sdio.c
@@ -295,6 +295,12 @@ 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.
*/
diff --git a/drivers/mmc/host/mxcmmc.c b/drivers/mmc/host/mxcmmc.c
index 51e880c8f193..2c53024ee439 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)
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 43eaf5ca5848..3196c84cc630 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;
--
2.34.1