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authorPaul Walmsley <paul@pwsan.com>2009-06-19 19:08:26 -0600
committerpaul <paul@twilight.(none)>2009-06-19 19:09:31 -0600
commitc9812d042a21eb492a36cfabf9f41107f5ecee3d (patch)
treef9443de1d4534b0b56bd1b0ff56bfc6d78eb698d /arch/arm/plat-omap
parent2f135eaf182761bb9a5cbd5138a447b0ad2a1fef (diff)
OMAP3 clock: add a short delay when lowering CORE clk rate
When changing the SDRAM clock from 166MHz to 83MHz via the CORE DPLL M2 divider, add a short delay before returning to SDRAM to allow the SDRC time to stabilize. Without this delay, the system is prone to random panics upon re-entering SDRAM. This time delay varies based on MPU frequency. At 500MHz MPU frequency at room temperature, 64 loops seems to work okay; so add another 32 loops for environmental and process variation. Signed-off-by: Paul Walmsley <paul@pwsan.com>
Diffstat (limited to 'arch/arm/plat-omap')
-rw-r--r--arch/arm/plat-omap/include/mach/sram.h4
-rw-r--r--arch/arm/plat-omap/sram.c8
2 files changed, 7 insertions, 5 deletions
diff --git a/arch/arm/plat-omap/include/mach/sram.h b/arch/arm/plat-omap/include/mach/sram.h
index dca7c16ae903..c32fa0a220dc 100644
--- a/arch/arm/plat-omap/include/mach/sram.h
+++ b/arch/arm/plat-omap/include/mach/sram.h
@@ -24,7 +24,7 @@ extern u32 omap2_set_prcm(u32 dpll_ctrl_val, u32 sdrc_rfr_val, int bypass);
extern u32 omap3_configure_core_dpll(u32 sdrc_rfr_ctrl,
u32 sdrc_actim_ctrla,
u32 sdrc_actim_ctrlb, u32 m2,
- u32 unlock_dll);
+ u32 unlock_dll, u32 f);
/* Do not use these */
extern void omap1_sram_reprogram_clock(u32 ckctl, u32 dpllctl);
@@ -62,7 +62,7 @@ extern unsigned long omap243x_sram_reprogram_sdrc_sz;
extern u32 omap3_sram_configure_core_dpll(u32 sdrc_rfr_ctrl,
u32 sdrc_actim_ctrla,
u32 sdrc_actim_ctrlb, u32 m2,
- u32 unlock_dll);
+ u32 unlock_dll, u32 f);
extern unsigned long omap3_sram_configure_core_dpll_sz;
#endif
diff --git a/arch/arm/plat-omap/sram.c b/arch/arm/plat-omap/sram.c
index a5b9bcd6b108..79c0f0254426 100644
--- a/arch/arm/plat-omap/sram.c
+++ b/arch/arm/plat-omap/sram.c
@@ -371,15 +371,17 @@ static inline int omap243x_sram_init(void)
static u32 (*_omap3_sram_configure_core_dpll)(u32 sdrc_rfr_ctrl,
u32 sdrc_actim_ctrla,
u32 sdrc_actim_ctrlb,
- u32 m2, u32 unlock_dll);
+ u32 m2, u32 unlock_dll,
+ u32 f);
u32 omap3_configure_core_dpll(u32 sdrc_rfr_ctrl, u32 sdrc_actim_ctrla,
- u32 sdrc_actim_ctrlb, u32 m2, u32 unlock_dll)
+ u32 sdrc_actim_ctrlb, u32 m2, u32 unlock_dll,
+ u32 f)
{
BUG_ON(!_omap3_sram_configure_core_dpll);
return _omap3_sram_configure_core_dpll(sdrc_rfr_ctrl,
sdrc_actim_ctrla,
sdrc_actim_ctrlb, m2,
- unlock_dll);
+ unlock_dll, f);
}
/* REVISIT: Should this be same as omap34xx_sram_init() after off-idle? */