davinci: PSC: Clear bits in MDCTL reg before setting new bits

Clear any set bits in the 'NEXT' field of the MDCTL register in the
Power and Sleep Controller (PSC) before setting any new bits.
This also allows some minor cleanup by removing some no longer
needed lines of code.
Signed-off-by: Mark A. Greer <mgreer@mvista.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

arch/arm/mach-davinci/psc.c

@@ -39,6 +39,7 @@
 #define MDSTAT		0x800
 #define MDCTL		0xA00
 
+#define MDSTAT_STATE_MASK 0x1f
 
 /* Return nonzero iff the domain's clock is active */
 int __init davinci_psc_is_clk_active(unsigned int id)
@@ -53,14 +54,13 @@ int __init davinci_psc_is_clk_active(unsigned int id)
 /* Enable or disable a PSC domain */
 void davinci_psc_config(unsigned int domain, unsigned int id, char enable)
 {
-	u32 epcpr, ptcmd, ptstat, pdstat, pdctl1, mdstat, mdctl, mdstat_mask;
+	u32 epcpr, ptcmd, ptstat, pdstat, pdctl1, mdstat, mdctl;
 	void __iomem *psc_base = IO_ADDRESS(DAVINCI_PWR_SLEEP_CNTRL_BASE);
+	u32 next_state = enable ? 0x3 : 0x2; /* 0x3 enables, 0x2 disables */
 
 	mdctl = __raw_readl(psc_base + MDCTL + 4 * id);
-	if (enable)
-		mdctl |= 0x00000003;	/* Enable Module */
-	else
-		mdctl &= 0xFFFFFFE2;	/* Disable Module */
+	mdctl &= ~MDSTAT_STATE_MASK;
+	mdctl |= next_state;
 	__raw_writel(mdctl, psc_base + MDCTL + 4 * id);
 
 	pdstat = __raw_readl(psc_base + PDSTAT);
@@ -93,12 +93,7 @@ void davinci_psc_config(unsigned int domain, unsigned int id, char enable)
 		} while (!(((ptstat >> domain) & 1) == 0));
 	}
 
-	if (enable)
-		mdstat_mask = 0x3;
-	else
-		mdstat_mask = 0x2;
-
 	do {
 		mdstat = __raw_readl(psc_base + MDSTAT + 4 * id);
-	} while (!((mdstat & 0x0000001F) == mdstat_mask));
+	} while (!((mdstat & MDSTAT_STATE_MASK) == next_state));
 }