[PATCH 02/10] OMAP3 clock: initialize SDRC timings at kernel start

[Paul Walmsley]

On the OMAP3, initialize SDRC timings when the kernel boots.  This ensures
that the kernel is running with known, optimized SDRC timings, rather than
whatever was configured by the bootloader.

Signed-off-by: Paul Walmsley <paul@xxxxxxxxx>
---
 arch/arm/mach-omap2/clock34xx.c |    3 ---
 arch/arm/mach-omap2/io.c        |   38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/arch/arm/mach-omap2/clock34xx.c b/arch/arm/mach-omap2/clock34xx.c
index 62092f2..a62e326 100644
--- a/arch/arm/mach-omap2/clock34xx.c
+++ b/arch/arm/mach-omap2/clock34xx.c
@@ -715,9 +715,6 @@ static int omap3_core_dpll_m2_set_rate(struct clk *clk, unsigned long rate)
 	if (clk != &dpll3_m2_ck)
 		return -EINVAL;
 
-	if (rate == clk->rate)
-		return 0;
-
 	validrate = omap2_clksel_round_rate_div(clk, rate, &new_div);
 	if (validrate != rate)
 		return -EINVAL;
diff --git a/arch/arm/mach-omap2/io.c b/arch/arm/mach-omap2/io.c
index 916fcd3..2756f49 100644
--- a/arch/arm/mach-omap2/io.c
+++ b/arch/arm/mach-omap2/io.c
@@ -19,6 +19,7 @@
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/io.h>
+#include <linux/clk.h>
 
 #include <asm/tlb.h>
 
@@ -195,6 +196,40 @@ void __init omap2_map_common_io(void)
 	omapfb_reserve_sdram();
 }
 
+/*
+ * omap2_init_reprogram_sdrc - reprogram SDRC timing parameters
+ *
+ * Sets the CORE DPLL3 M2 divider to the same value that it's at
+ * currently.  This has the effect of setting the SDRC SDRAM AC timing
+ * registers to the values currently defined by the kernel.  Currently
+ * only defined for OMAP3; will return 0 if called on OMAP2.  Returns
+ * -EINVAL if the dpll3_m2_ck cannot be found, 0 if called on OMAP2,
+ * or passes along the return value of clk_set_rate().
+ */
+static int __init _omap2_init_reprogram_sdrc(void)
+{
+	struct clk *dpll3_m2_ck;
+	int v = -EINVAL;
+	long rate;
+
+	if (!cpu_is_omap34xx())
+		return 0;
+
+	dpll3_m2_ck = clk_get(NULL, "dpll3_m2_ck");
+	if (!dpll3_m2_ck)
+		return -EINVAL;
+
+	rate = clk_get_rate(dpll3_m2_ck);
+	pr_info("Reprogramming SDRC clock to %ld Hz\n", rate);
+	v = clk_set_rate(dpll3_m2_ck, rate);
+	if (v)
+		pr_err("dpll3_m2_clk rate change failed: %d\n", v);
+
+	clk_put(dpll3_m2_ck);
+
+	return v;
+}
+
 void __init omap2_init_common_hw(struct omap_sdrc_params *sp)
 {
 	omap2_mux_init();
@@ -202,5 +237,8 @@ void __init omap2_init_common_hw(struct omap_sdrc_params *sp)
 	clkdm_init(clockdomains_omap, clkdm_pwrdm_autodeps);
 	omap2_clk_init();
 	omap2_sdrc_init(sp);
+
+	_omap2_init_reprogram_sdrc();
+
 	gpmc_init();
 }


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