From: Jerry Huang <Chang-Ming.Huang@xxxxxxxxxxxxx>
SD card read was failing (data crc error)on some cards at
maximum possible frequency on P1010(CCB frequency set to 400MHz).
Some clock deviations are also observed at this frequency.
Hence reduced the mmc clock freq.
Signed-off-by: Priyanka Jain <Priyanka.Jain@xxxxxxxxxxxxx>
Singed-off-by: Jerry Huang <Chang-Ming.Huang@xxxxxxxxxxxxx>
CC: Chris Ball <cjb@xxxxxxxxxx>
---
changes for v2:
- change the property to compatible for quirks
changes for v3:
- fix one compile error
drivers/mmc/host/sdhci-esdhc.h | 9 ++++++++-
drivers/mmc/host/sdhci-pltfm.c | 3 +++
include/linux/mmc/sdhci.h | 2 ++
3 files changed, 13 insertions(+), 1 deletions(-)
diff --git a/drivers/mmc/host/sdhci-esdhc.h b/drivers/mmc/host/sdhci-esdhc.h
index b97b2f5..8e00174 100644
--- a/drivers/mmc/host/sdhci-esdhc.h
+++ b/drivers/mmc/host/sdhci-esdhc.h
@@ -1,7 +1,7 @@
/*
* Freescale eSDHC controller driver generics for OF and pltfm.
*
- * Copyright (c) 2007 Freescale Semiconductor, Inc.
+ * Copyright (c) 2007,2011 Freescale Semiconductor, Inc.
* Copyright (c) 2009 MontaVista Software, Inc.
* Copyright (c) 2010 Pengutronix e.K.
* Author: Wolfram Sang <w.sang@xxxxxxxxxxxxxx>
@@ -56,6 +56,13 @@ static inline void esdhc_set_clock(struct sdhci_host *host, unsigned int clock)
if (clock == 0)
goto out;
+ if (host->quirks2 & SDHCI_QUIRK2_RELAX_FREQ) {
+ if (clock > 20000000)
+ clock -= 5000000;
+ if (clock > 40000000)
+ clock -= 5000000;
+ }
+
while (host->max_clk / pre_div / 16 > clock && pre_div < 256)
pre_div *= 2;
diff --git a/drivers/mmc/host/sdhci-pltfm.c b/drivers/mmc/host/sdhci-pltfm.c
index d0efee3..06f4ab9 100644
--- a/drivers/mmc/host/sdhci-pltfm.c
+++ b/drivers/mmc/host/sdhci-pltfm.c
@@ -83,6 +83,9 @@ void sdhci_get_of_property(struct platform_device *pdev)
|| of_device_is_compatible(np, "fsl,mpc8536-esdhc"))
host->quirks |= SDHCI_QUIRK_BROKEN_TIMEOUT_VAL;
+ if (of_device_is_compatible(np, "fsl,p1010-esdhc"))
+ host->quirks2 |= SDHCI_QUIRK2_RELAX_FREQ;
+
#ifdef CONFIG_PM
if (of_device_is_compatible(np, "fsl,p1022-esdhc")
sdhc_pmsaveproctlreg = 1;
diff --git a/include/linux/mmc/sdhci.h b/include/linux/mmc/sdhci.h
index e4b6935..f7c1e13 100644
--- a/include/linux/mmc/sdhci.h
+++ b/include/linux/mmc/sdhci.h
@@ -91,6 +91,8 @@ struct sdhci_host {
unsigned int quirks2; /* More deviations from spec. */
#define SDHCI_QUIRK2_OWN_CARD_DETECTION (1<<0)
+/* Controller operates the cards at reduced frequency */
+#define SDHCI_QUIRK2_RELAX_FREQ (1<<1)
int irq; /* Device IRQ */
void __iomem *ioaddr; /* Mapped address */
--
1.7.5.4
--
To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
