[U-Boot] [PATCH 07/23] mmc: omap_hsmmc: Workaround for errata id i802

[Jean-Jacques Hiblot]

From: Kishon Vijay Abraham I <kishon at ti.com>

According to errata i802, DCRC error interrupts
(MMCHS_STAT[21] DCRC=0x1) can occur during the tuning procedure.

The DCRC interrupt, occurs when the last tuning block fails
(the last ratio tested). The delay from CRC check until the
interrupt is asserted is bigger than the delay until assertion
of the tuning end flag. Assertion of tuning end flag is what
masks the interrupts. Because of this race, an erroneous DCRC
interrupt occurs.

The suggested  workaround is to disable DCRC interrupts during
the tuning procedure which is implemented here.

Signed-off-by: Kishon Vijay Abraham I <kishon at ti.com>
Signed-off-by: Jean-Jacques Hiblot <jjhiblot at ti.com>
---
 arch/arm/include/asm/omap_mmc.h |  4 ++++
 drivers/mmc/omap_hsmmc.c        | 26 ++++++++++++++++++++++----
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/arch/arm/include/asm/omap_mmc.h b/arch/arm/include/asm/omap_mmc.h
index 0293281..0893844 100644
--- a/arch/arm/include/asm/omap_mmc.h
+++ b/arch/arm/include/asm/omap_mmc.h
@@ -219,6 +219,10 @@ struct omap_hsmmc_plat {
 #define mmc_reg_out(addr, mask, val)\
 	writel((readl(addr) & (~(mask))) | ((val) & (mask)), (addr))
 
+#define INT_EN_MASK (IE_BADA | IE_CERR | IE_DEB | IE_DCRC |\
+		IE_DTO | IE_CIE | IE_CEB | IE_CCRC | IE_ADMAE | IE_CTO |\
+		IE_BRR | IE_BWR | IE_TC | IE_CC)
+
 int omap_mmc_init(int dev_index, uint host_caps_mask, uint f_max, int cd_gpio,
 		int wp_gpio);
 
diff --git a/drivers/mmc/omap_hsmmc.c b/drivers/mmc/omap_hsmmc.c
index 321a091..8e42410 100644
--- a/drivers/mmc/omap_hsmmc.c
+++ b/drivers/mmc/omap_hsmmc.c
@@ -474,6 +474,25 @@ tuning_error:
 }
 #endif
 
+static void mmc_enable_irq(struct mmc *mmc, struct mmc_cmd *cmd)
+{
+	struct omap_hsmmc_data *priv = omap_hsmmc_get_data(mmc);
+	struct hsmmc *mmc_base = priv->base_addr;
+	u32 irq_mask = INT_EN_MASK;
+
+	/*
+	 * TODO: Errata i802 indicates only DCRC interrupts can occur during
+	 * tuning procedure and DCRC should be disabled. But see occurences
+	 * of DEB, CIE, CEB, CCRC interupts during tuning procedure. These
+	 * interrupts occur along with BRR, so the data is actually in the
+	 * buffer. It has to be debugged why these interrutps occur
+	 */
+	if (cmd && mmc_is_tuning_cmd(cmd->cmdidx))
+		irq_mask &= ~(IE_DEB | IE_DCRC | IE_CIE | IE_CEB | IE_CCRC);
+
+	writel(irq_mask, &mmc_base->ie);
+}
+
 static int omap_hsmmc_init_setup(struct mmc *mmc)
 {
 	struct omap_hsmmc_data *priv = omap_hsmmc_get_data(mmc);
@@ -540,10 +559,7 @@ static int omap_hsmmc_init_setup(struct mmc *mmc)
 
 	writel(readl(&mmc_base->hctl) | SDBP_PWRON, &mmc_base->hctl);
 
-	writel(IE_BADA | IE_CERR | IE_DEB | IE_DCRC | IE_DTO | IE_CIE |
-		IE_CEB | IE_CCRC | IE_ADMAE | IE_CTO | IE_BRR | IE_BWR | IE_TC |
-		IE_CC, &mmc_base->ie);
-
+	mmc_enable_irq(mmc, NULL);
 	mmc_init_stream(mmc_base);
 
 	return 0;
@@ -806,6 +822,8 @@ static int omap_hsmmc_send_cmd(struct udevice *dev, struct mmc_cmd *cmd,
 #endif
 	}
 
+	mmc_enable_irq(mmc, cmd);
+
 	writel(cmd->cmdarg, &mmc_base->arg);
 	udelay(20);		/* To fix "No status update" error on eMMC */
 	writel((cmd->cmdidx << 24) | flags, &mmc_base->cmd);
-- 
1.9.1