commit f0b5f23f32adfb790293c4f1722042026fa98416
author Eric Nelson <eric@nelint.com> Fri Dec 04 12:32:48 2015 -0700
committer Stefano Babic <sbabic@denx.de> Sun Jan 03 15:21:21 2016 +0100
tree af067eff7e525a63c19c32459d496068218c0d36
parent 839479dda6b449d911d1d56c599f2a9538bb2215

ARM: imx: fsl_esdhc: fix usage of low 4 bits of sysctl register

The low four bits of the SYSCTL register are reserved on the USDHC
controller on i.MX6 and i.MX7 processors, but are used for clocking
operations on earlier models.

Guard against their usage by hiding the bit mask macros on those
processors.

These bits are used to prevent glitches when changing clocks on
i.MX35 et al. Use the RSTA bit instead for i.MX6 and i.MX7.

>From the i.MX6DQ RM:
	To prevent possible glitch on the card clock, clear the
	FRC_SDCLK_ON bit when changing clock divisor value(SDCLKFS
	or DVS in System Control Register) or setting RSTA bit.

Signed-off-by: Eric Nelson <eric@nelint.com>
Reviewed-by: Fabio Estevam <fabio.estevam@freescale.com>
Reviewed-by: Stefano Babic <sbabic@denx.de>
Reviewed-by: Hector Palacios <hector.palacios@digi.com>

drivers/mmc/fsl_esdhc.c

diff --git a/drivers/mmc/fsl_esdhc.c b/drivers/mmc/fsl_esdhc.c
index c5054d6..1ccc576 100644
--- a/drivers/mmc/fsl_esdhc.c
+++ b/drivers/mmc/fsl_esdhc.c
@@ -502,15 +502,22 @@
 
 	clk = (pre_div << 8) | (div << 4);
 
+#ifdef CONFIG_FSL_USDHC
+	esdhc_setbits32(&regs->sysctl, SYSCTL_RSTA);
+#else
 	esdhc_clrbits32(&regs->sysctl, SYSCTL_CKEN);
+#endif
 
 	esdhc_clrsetbits32(&regs->sysctl, SYSCTL_CLOCK_MASK, clk);
 
 	udelay(10000);
 
-	clk = SYSCTL_PEREN | SYSCTL_CKEN;
+#ifdef CONFIG_FSL_USDHC
+	esdhc_clrbits32(&regs->sysctl, SYSCTL_RSTA);
+#else
+	esdhc_setbits32(&regs->sysctl, SYSCTL_PEREN | SYSCTL_CKEN);
+#endif
 
-	esdhc_setbits32(&regs->sysctl, clk);
 }
 
 #ifdef CONFIG_FSL_ESDHC_USE_PERIPHERAL_CLK
@@ -585,7 +592,9 @@
 	esdhc_write32(&regs->scr, 0x00000040);
 #endif
 
+#ifndef CONFIG_FSL_USDHC
 	esdhc_setbits32(&regs->sysctl, SYSCTL_HCKEN | SYSCTL_IPGEN);
+#endif
 
 	/* Set the initial clock speed */
 	mmc_set_clock(mmc, 400000);
@@ -657,8 +666,10 @@
 	/* First reset the eSDHC controller */
 	esdhc_reset(regs);
 
+#ifndef CONFIG_FSL_USDHC
 	esdhc_setbits32(&regs->sysctl, SYSCTL_PEREN | SYSCTL_HCKEN
 				| SYSCTL_IPGEN | SYSCTL_CKEN);
+#endif
 
 	writel(SDHCI_IRQ_EN_BITS, &regs->irqstaten);
 	memset(&cfg->cfg, 0, sizeof(cfg->cfg));