[U-Boot] [PATCH] mmc: omap: handle controller errors properly

[Grazvydas Ignotas]

According to OMAP3 TRM, when the controller reports certain errors,
driver must perform a software reset. This is done by setting a bit
in SYSCTL and waiting it to clear:
- SRC on command timeout (CTO)
- SRD on data errors (DTO, DCRC and DEB)

This fixes a problem seen on OMAP3 pandora board with some cards
that won't work with a message printed multiple times:
  timedout waiting on cmd inhibit to clear

Code loosely based on Linux omap_hsmmc driver.

Signed-off-by: Grazvydas Ignotas <notasas at gmail.com>
---
 drivers/mmc/omap_hsmmc.c |   36 ++++++++++++++++++++++++++++++++++--
 1 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/omap_hsmmc.c b/drivers/mmc/omap_hsmmc.c
index 4b81d0d..06cbebf 100644
--- a/drivers/mmc/omap_hsmmc.c
+++ b/drivers/mmc/omap_hsmmc.c
@@ -33,6 +33,10 @@
 #include <asm/arch/mmc_host_def.h>
 #include <asm/arch/sys_proto.h>
 
+/* common definitions for all OMAPs */
+#define SYSCTL_SRC	(1 << 25)
+#define SYSCTL_SRD	(1 << 26)
+
 /* If we fail after 1 second wait, something is really bad */
 #define MAX_RETRY_MS	1000
 
@@ -195,6 +199,27 @@ static int mmc_init_setup(struct mmc *mmc)
 	return 0;
 }
 
+/*
+ * MMC controller internal finite state machine reset
+ *
+ * Used to reset command or data internal state machines, using respectively
+ * SRC or SRD bit of SYSCTL register
+ */
+static void mmc_reset_controller_fsm(struct hsmmc *mmc_base, u32 bit)
+{
+	ulong start;
+
+	mmc_reg_out(&mmc_base->sysctl, bit, bit);
+
+	start = get_timer(0);
+	while ((readl(&mmc_base->sysctl) & bit) != 0) {
+		if (get_timer(0) - start > MAX_RETRY_MS) {
+			printf("%s: timedout waiting for sysctl %x to clear\n",
+				__func__, bit);
+			return;
+		}
+	}
+}
 
 static int mmc_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd,
 			struct mmc_data *data)
@@ -284,9 +309,10 @@ static int mmc_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd,
 		}
 	} while (!mmc_stat);
 
-	if ((mmc_stat & IE_CTO) != 0)
+	if ((mmc_stat & IE_CTO) != 0) {
+		mmc_reset_controller_fsm(mmc_base, SYSCTL_SRC);
 		return TIMEOUT;
-	else if ((mmc_stat & ERRI_MASK) != 0)
+	} else if ((mmc_stat & ERRI_MASK) != 0)
 		return -1;
 
 	if (mmc_stat & CC_MASK) {
@@ -337,6 +363,9 @@ static int mmc_read_data(struct hsmmc *mmc_base, char *buf, unsigned int size)
 			}
 		} while (mmc_stat == 0);
 
+		if ((mmc_stat & (IE_DTO | IE_DCRC | IE_DEB)) != 0)
+			mmc_reset_controller_fsm(mmc_base, SYSCTL_SRD);
+
 		if ((mmc_stat & ERRI_MASK) != 0)
 			return 1;
 
@@ -389,6 +418,9 @@ static int mmc_write_data(struct hsmmc *mmc_base, const char *buf,
 			}
 		} while (mmc_stat == 0);
 
+		if ((mmc_stat & (IE_DTO | IE_DCRC | IE_DEB)) != 0)
+			mmc_reset_controller_fsm(mmc_base, SYSCTL_SRD);
+
 		if ((mmc_stat & ERRI_MASK) != 0)
 			return 1;
 
-- 
1.7.0.4