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OMAP3 SDRC: set FIXEDDELAY when disabling SDRC DLL

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Correspondence with the TI OMAP hardware team indicates that
SDRC_DLLA_CTRL.FIXEDDELAY should be initialized to 0x0f.  This number
was apparently derived from process validation.  This is only used
when the SDRC DLL is unlocked (e.g., SDRC clock frequency less than
83MHz).

Signed-off-by: Paul Walmsley <paul@pwsan.com>
This commit is contained in:
Paul Walmsley 2009-06-19 19:08:29 -06:00 committed by paul
parent 3afec6332e
commit 7b7bcefa35
1 changed files with 12 additions and 0 deletions
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12
arch/arm/mach-omap2/sram34xx.S
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@ -41,8 +41,18 @@
#define SDRC_UNLOCK_DLL 0x1
/* SDRC_DLLA_CTRL bit settings */
#define FIXEDDELAY_SHIFT 24
#define FIXEDDELAY_MASK (0xff << FIXEDDELAY_SHIFT)
#define DLLIDLE_MASK 0x4
/*
* SDRC_DLLA_CTRL default values: TI hardware team indicates that
* FIXEDDELAY should be initialized to 0xf. This apparently was
* empirically determined during process testing, so no derivation
* was provided.
*/
#define FIXEDDELAY_DEFAULT (0x0f << FIXEDDELAY_SHIFT)
/* SDRC_DLLA_STATUS bit settings */
#define LOCKSTATUS_MASK 0x4
@ -103,6 +113,8 @@ return_to_sdram:
unlock_dll:
ldr r11, omap3_sdrc_dlla_ctrl
ldr r12, [r11]
and r12, r12, #FIXEDDELAY_MASK
orr r12, r12, #FIXEDDELAY_DEFAULT
orr r12, r12, #DLLIDLE_MASK
str r12, [r11] @ (no OCP barrier needed)
bx lr