[PATCH 7/8] omap3: Avoid sudden change to SYS_CLK divider

[Sanjeev Premi]

In function get_osc_clk_speed(), the SYS_CLK divider
was being changed 'suddenly'.

This change has cascading effect on the derived clocks,
leading to inconsistent behavior - often a crash.

Signed-off-by: Sanjeev Premi <premi at ti.com>
---
 arch/arm/mach-omap/include/mach/omap3-clock.h |    6 ++++++
 arch/arm/mach-omap/omap3_clock.c              |   19 +++++++++++++++----
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mach-omap/include/mach/omap3-clock.h b/arch/arm/mach-omap/include/mach/omap3-clock.h
index b9e2714..cccb0da 100644
--- a/arch/arm/mach-omap/include/mach/omap3-clock.h
+++ b/arch/arm/mach-omap/include/mach/omap3-clock.h
@@ -92,6 +92,12 @@
 #define PLL_FAST_RELOCK_BYPASS	6	/* CORE */
 #define PLL_LOCK		7	/* MPU, IVA, CORE & PER */
 
+/*
+ * Bit positions indicating current SYSCLK divider
+ */
+#define SYSCLK_DIV_1		(1 << 6)
+#define SYSCLK_DIV_2		(1 << 7)
+
 /* The following configurations are OPP and SysClk value independant
  * and hence are defined here.
  */
diff --git a/arch/arm/mach-omap/omap3_clock.c b/arch/arm/mach-omap/omap3_clock.c
index 1668369..16cbae9 100644
--- a/arch/arm/mach-omap/omap3_clock.c
+++ b/arch/arm/mach-omap/omap3_clock.c
@@ -65,12 +65,20 @@ static void per_clocks_enable(void);
  */
 static u32 get_osc_clk_speed(void)
 {
-	u32 start, cstart, cend, cdiff, val;
+	u32 start, cstart, cend, cdiff, cdiv, val;
 
 	val = readl(PRM_REG(CLKSRC_CTRL));
-	/* If SYS_CLK is being divided by 2, remove for now */
-	val = (val & (~(0x1 << 7))) | (0x1 << 6);
-	writel(val, PRM_REG(CLKSRC_CTRL));
+
+	if (val & SYSCLK_DIV_2)
+		cdiv = 2;
+	else if (val & SYSCLK_DIV_1)
+		cdiv = 1;
+	else
+		/*
+		 * Should never reach here!
+		 * To proceed, assume divider as 1.
+		 */
+		cdiv = 1;
 
 	/* enable timer2 */
 	val = readl(CM_REG(CLKSEL_WKUP)) | (0x1 << 0);
@@ -97,6 +105,9 @@ static u32 get_osc_clk_speed(void)
 	cend = readl(OMAP_GPTIMER1_BASE + TCRR);
 	cdiff = cend - cstart;	/* get elapsed ticks */
 
+	if (cdiv == 2)
+		cdiff *= 2;
+
 	/* based on number of ticks assign speed */
 	if (cdiff > 19000)
 		return S38_4M;
-- 
1.7.2.2