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OMAP3 clock: initialize SDRC timings at kernel start

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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>
This commit is contained in:
Paul Walmsley 2009-06-19 19:08:25 -06:00 committed by paul
parent 6adb8f388e
commit 2f135eaf18
2 changed files with 36 additions and 3 deletions
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3
arch/arm/mach-omap2/clock34xx.c
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@ -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;

36
arch/arm/mach-omap2/io.c
View file

@ -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();
}