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| author | David Jander <david@protonic.nl> | 2011-07-13 21:11:53 +0000 |
|---|---|---|
| committer | Albert ARIBAUD <albert.u.boot@aribaud.net> | 2011-09-04 11:36:11 +0200 |
| commit | 9db1bfa110ac411ab3468e817f7f74b2439eb8c8 (patch) | |
| tree | c9fd5e7dc463937e8642e410c644ebdf067dfbe3 /arch/arm/cpu | |
| parent | 96c9745fa1f03a0e24d09a32344a1f0c821bc9af (diff) | |
| download | u-boot-imx-9db1bfa110ac411ab3468e817f7f74b2439eb8c8.zip u-boot-imx-9db1bfa110ac411ab3468e817f7f74b2439eb8c8.tar.gz u-boot-imx-9db1bfa110ac411ab3468e817f7f74b2439eb8c8.tar.bz2 | |
ARM: MX51: PLL errata workaround
This is a port of the official PLL errata workaround from Freescale to
mainline u-boot.
The PLL's in the i.MX51 processor can go out of lock due to a metastable
condition in an analog flip-flop when used at high frequencies.
This workaround implements an undocumented feature in the PLL (dither
mode), which causes the effect of this failure to be much lower (in terms
of frequency deviation), avoiding system failure, or at least decreasing
the likelihood of system failure.
Signed-off-by: David Jander <david@protonic.nl>
Diffstat (limited to 'arch/arm/cpu')
| -rw-r--r-- | arch/arm/cpu/armv7/mx5/lowlevel_init.S | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/arch/arm/cpu/armv7/mx5/lowlevel_init.S b/arch/arm/cpu/armv7/mx5/lowlevel_init.S index 94de9f1..6c66b42 100644 --- a/arch/arm/cpu/armv7/mx5/lowlevel_init.S +++ b/arch/arm/cpu/armv7/mx5/lowlevel_init.S @@ -121,6 +121,35 @@ beq 1b .endm +.macro setup_pll_errata pll, freq + ldr r2, =\pll + mov r1, #0x0 + str r1, [r2, #PLL_DP_CONFIG] /* Disable auto-restart AREN bit */ + ldr r1, =0x00001236 + str r1, [r2, #PLL_DP_CTL] /* Restart PLL with PLM=1 */ +1: ldr r1, [r2, #PLL_DP_CTL] /* Wait for lock */ + ands r1, r1, #0x1 + beq 1b + + ldr r5, \freq + str r5, [r2, #PLL_DP_MFN] /* Modify MFN value */ + str r5, [r2, #PLL_DP_HFS_MFN] + + mov r1, #0x1 + str r1, [r2, #PLL_DP_CONFIG] /* Reload MFN value */ + +2: ldr r1, [r2, #PLL_DP_CONFIG] + tst r1, #1 + bne 2b + + ldr r1, =100 /* Wait at least 4 us */ +3: subs r1, r1, #1 + bge 3b + + mov r1, #0x2 + str r1, [r2, #PLL_DP_CONFIG] /* Enable auto-restart AREN bit */ +.endm + .macro init_clock ldr r0, =CCM_BASE_ADDR @@ -157,7 +186,12 @@ mov r1, #0x4 str r1, [r0, #CLKCTL_CCSR] +#if defined(CONFIG_MX51_PLL_ERRATA) + setup_pll PLL1_BASE_ADDR, 864 + setup_pll_errata PLL1_BASE_ADDR, W_DP_MFN_800_DIT +#else setup_pll PLL1_BASE_ADDR, 800 +#endif #if defined(CONFIG_MX51) setup_pll PLL3_BASE_ADDR, 665 @@ -287,6 +321,10 @@ lowlevel_init: mov pc,lr /* Board level setting value */ +W_DP_OP_864: .word DP_OP_864 +W_DP_MFD_864: .word DP_MFD_864 +W_DP_MFN_864: .word DP_MFN_864 +W_DP_MFN_800_DIT: .word DP_MFN_800_DIT W_DP_OP_800: .word DP_OP_800 W_DP_MFD_800: .word DP_MFD_800 W_DP_MFN_800: .word DP_MFN_800 |