[U-Boot] [PATCH] arm: mvebu: set 38x and 39x AVS on lower frequency
Chris Packham
judge.packham at gmail.com
Wed Jun 26 05:07:20 UTC 2019
On Tue, Jun 25, 2019 at 7:49 PM Chris Packham <judge.packham at gmail.com> wrote:
>
> On Tue, Jun 25, 2019 at 5:50 PM Baruch Siach <baruch at tkos.co.il> wrote:
> >
> > Hi Chris,
> >
> > On Tue, Jun 25 2019, Chris Packham wrote:
> > > On Mon, Jun 24, 2019 at 8:30 PM Baruch Siach <baruch at tkos.co.il> wrote:
> > >>
> > >> Reduce Auto Voltage Scaling VDD limit when core frequency is lower than
> > >> 1600MHz. This reduces core voltage level from 1.25V to 1.15V, which
> > >> saves power.
> > >>
> > >> The code is taken from Marvell's U-Boot 2013.01 revision 18.06.
> > >>
> > >> Signed-off-by: Baruch Siach <baruch at tkos.co.il>
> > >
> > > I gave it a quick spin on DB-88F6820-AMC and x530. Both booted fine.
> >
> > Is there AVS feedback circuit on these boards? If so, have you measured
> > how this patch affects core voltage?
> >
>
> Both boards have circuitry for AVS_FB although the x530 strapping will
> probably mean that this code skips it. I'll see if I can measure and
> difference in behaviour tomorrow.
>
I did a quick check on the DB-88F6820-AMC board. Before your patch I
measured 1.261V on the V_CPU rail. After your patch I measured 1.166V.
> > > Reviewed-by: Chris Packham <judge.packham at gmail.com>
> > > Tested-by: Chris Packham <judge.packham at gmail.com>
> >
> > Thanks,
> > baruch
> >
> > >> ---
> > >> arch/arm/mach-mvebu/include/mach/cpu.h | 3 +++
> > >> arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.c | 26 +++++++++++++++++++
> > >> arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h | 4 +++
> > >> arch/arm/mach-mvebu/spl.c | 3 +++
> > >> 4 files changed, 36 insertions(+)
> > >>
> > >> diff --git a/arch/arm/mach-mvebu/include/mach/cpu.h b/arch/arm/mach-mvebu/include/mach/cpu.h
> > >> index e6140d67293e..e1128ee90f01 100644
> > >> --- a/arch/arm/mach-mvebu/include/mach/cpu.h
> > >> +++ b/arch/arm/mach-mvebu/include/mach/cpu.h
> > >> @@ -163,6 +163,9 @@ int serdes_phy_config(void);
> > >> */
> > >> int ddr3_init(void);
> > >>
> > >> +/* Auto Voltage Scaling */
> > >> +void mv_avs_init(void);
> > >> +
> > >> /*
> > >> * get_ref_clk
> > >> *
> > >> diff --git a/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.c b/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.c
> > >> index d387893af37d..e9dd096ad0f5 100644
> > >> --- a/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.c
> > >> +++ b/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.c
> > >> @@ -256,3 +256,29 @@ u8 sys_env_device_rev_get(void)
> > >> value = reg_read(DEV_VERSION_ID_REG);
> > >> return (value & (REVISON_ID_MASK)) >> REVISON_ID_OFFS;
> > >> }
> > >> +
> > >> +void mv_avs_init(void)
> > >> +{
> > >> + u32 sar_freq;
> > >> +
> > >> + if (!(IS_ENABLED(CONFIG_ARMADA_38X) || IS_ENABLED(CONFIG_ARMADA_39X)))
> > >> + return;
> > >> +
> > >> + reg_write(AVS_DEBUG_CNTR_REG, AVS_DEBUG_CNTR_DEFAULT_VALUE);
> > >> + reg_write(AVS_DEBUG_CNTR_REG, AVS_DEBUG_CNTR_DEFAULT_VALUE);
> > >> +
> > >> + sar_freq = reg_read(DEVICE_SAMPLE_AT_RESET1_REG);
> > >> + sar_freq = sar_freq >> SAR_FREQ_OFFSET & SAR_FREQ_MASK;
> > >> +
> > >> + /* Set AVS value only for core frequency of 1600MHz or less.
> > >> + * For higher frequency leave the default value.
> > >> + */
> > >> + if (sar_freq <= 0xd) {
> > >> + u32 avs_reg_data = reg_read(AVS_ENABLED_CONTROL);
> > >> +
> > >> + avs_reg_data &= ~(AVS_LOW_VDD_LIMIT_MASK
> > >> + | AVS_HIGH_VDD_LIMIT_MASK);
> > >> + avs_reg_data |= AVS_LOW_VDD_SLOW_VAL | AVS_HIGH_VDD_SLOW_VAL;
> > >> + reg_write(AVS_ENABLED_CONTROL, avs_reg_data);
> > >> + }
> > >> +}
> > >> diff --git a/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h b/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h
> > >> index 365332d2b048..1774a5b780ca 100644
> > >> --- a/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h
> > >> +++ b/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h
> > >> @@ -33,6 +33,8 @@
> > >> #define DEV_ID_REG_DEVICE_ID_OFFS 16
> > >> #define DEV_ID_REG_DEVICE_ID_MASK 0xffff0000
> > >>
> > >> +#define SAR_FREQ_OFFSET 10
> > >> +#define SAR_FREQ_MASK 0x1f
> > >> #define SAR_DEV_ID_OFFS 27
> > >> #define SAR_DEV_ID_MASK 0x7
> > >>
> > >> @@ -155,10 +157,12 @@
> > >> #define AVS_LOW_VDD_LIMIT_OFFS 4
> > >> #define AVS_LOW_VDD_LIMIT_MASK (0xff << AVS_LOW_VDD_LIMIT_OFFS)
> > >> #define AVS_LOW_VDD_LIMIT_VAL (0x27 << AVS_LOW_VDD_LIMIT_OFFS)
> > >> +#define AVS_LOW_VDD_SLOW_VAL (0x23 << AVS_LOW_VDD_LIMIT_OFFS)
> > >>
> > >> #define AVS_HIGH_VDD_LIMIT_OFFS 12
> > >> #define AVS_HIGH_VDD_LIMIT_MASK (0xff << AVS_HIGH_VDD_LIMIT_OFFS)
> > >> #define AVS_HIGH_VDD_LIMIT_VAL (0x27 << AVS_HIGH_VDD_LIMIT_OFFS)
> > >> +#define AVS_HIGH_VDD_SLOW_VAL (0x23 << AVS_HIGH_VDD_LIMIT_OFFS)
> > >>
> > >> /* Board ID numbers */
> > >> #define MARVELL_BOARD_ID_MASK 0x10
> > >> diff --git a/arch/arm/mach-mvebu/spl.c b/arch/arm/mach-mvebu/spl.c
> > >> index d54de5195624..3cb27b7f4b20 100644
> > >> --- a/arch/arm/mach-mvebu/spl.c
> > >> +++ b/arch/arm/mach-mvebu/spl.c
> > >> @@ -126,6 +126,9 @@ void board_init_f(ulong dummy)
> > >> ddr3_init();
> > >> #endif
> > >>
> > >> + /* Initialize Auto Voltage Scaling */
> > >> + mv_avs_init();
> > >> +
> > >> /*
> > >> * Return to the BootROM to continue the Marvell xmodem
> > >> * UART boot protocol. As initiated by the kwboot tool.
> >
> > --
> > http://baruch.siach.name/blog/ ~. .~ Tk Open Systems
> > =}------------------------------------------------ooO--U--Ooo------------{=
> > - baruch at tkos.co.il - tel: +972.52.368.4656, http://www.tkos.co.il -
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