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authorPaul Walmsley <paul@pwsan.com>2009-06-19 19:08:25 -0600
committerpaul <paul@twilight.(none)>2009-06-19 19:09:30 -0600
commit2f135eaf182761bb9a5cbd5138a447b0ad2a1fef (patch)
treeceac7506d9d004dc0f6b2aaf56fd395fe411c1d7 /arch
parent6adb8f388ef2f23d4a81e1e42d15f22d62749a06 (diff)
OMAP3 clock: initialize SDRC timings at kernel start
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@pwsan.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/mach-omap2/clock34xx.c3
-rw-r--r--arch/arm/mach-omap2/io.c36
2 files changed, 36 insertions, 3 deletions
diff --git a/arch/arm/mach-omap2/clock34xx.c b/arch/arm/mach-omap2/clock34xx.c
index 9e43fe5209d..5458ab3bf65 100644
--- a/arch/arm/mach-omap2/clock34xx.c
+++ b/arch/arm/mach-omap2/clock34xx.c
@@ -718,9 +718,6 @@ 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 32afd944821..3a86b0f6603 100644
--- a/arch/arm/mach-omap2/io.c
+++ b/arch/arm/mach-omap2/io.c
@@ -21,6 +21,7 @@
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/io.h>
+#include <linux/clk.h>
#include <asm/tlb.h>
@@ -241,6 +242,40 @@ 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();
@@ -249,6 +284,7 @@ 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();
#endif
gpmc_init();
}