# Problem probing cpu Minimum freq[solved]

## sourcez

I have a laptop ACER Aspire 1350 with Athlon 2600+ XP.

In window$ my min cpu freq is 796,1 Mhz as output of CPU-Z (a cpuinfo utility) but on gentoo with gentoo-dev-sources-2.6.5-r1 or mm-sources-2.6.6-rc5 it's 1393 Mhz:

```
powernow: PowerNOW! Technology present. Can scale: frequency and voltage.

powernow: FSB: 132.688 MHz

powernow: Found PSB header at c00f06f0

powernow: Table version: 0x12

powernow: Flags: 0x0 (Mobile voltage regulator)

powernow: Settling Time: 100 microseconds.

powernow: Has 8 PST tables. (Only dumping ones relevant to this CPU).

powernow: PST:2 (@c00f072e)

powernow:  cpuid: 0x7a0 fsb: 133        maxFID: 0x18    startvid: 0x7

powernow:    FID: 0xf (10.5x [1393MHz]) VID: 0xe (1.300V)

powernow:    FID: 0x0 (11.0x [1459MHz]) VID: 0xd (1.350V)

powernow:    FID: 0x1 (11.5x [1525MHz]) VID: 0xc (1.400V)

powernow:    FID: 0x2 (12.0x [1592MHz]) VID: 0xb (1.450V)

powernow:    FID: 0x3 (12.5x [1658MHz]) VID: 0xa (1.500V)

powernow:    FID: 0x14 (13.0x [1724MHz])        VID: 0x9 (1.550V)

powernow:    FID: 0x15 (13.5x [1791MHz])        VID: 0x8 (1.600V)

powernow:    FID: 0x18 (15.0x [1990MHz])        VID: 0x7 (1.650V)

powernow: SGTC: 13333

powernow: Minimum speed 1393 MHz. Maximum speed 1990 MHz.

```

So I can't slow down my cpu freq under 1393 Mhz with any cpu_scaling utility  :Rolling Eyes: 

It seems be a problem of powernow-k7 driver...

How Can I specify a different minimum cpu_freq?

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## brodo

You can't specify it... it's in the BIOS. However, you can try compiling with CONFIG_ACPI_PROCESSOR="y" and, in case you built powernow-k7 as a module, pass "powernow_acpi_force=1" or "acpi_force=1" [depending on your kernel, please use 2.6.6-rc5 for this....] as module parameters; or if you built powernow-k7 into your kernel, add "powernow_k7.powernow_acpi_force=1" or "powernow_k7.acpi_force=1" to the kernel command line.

It forces using the ACPI tables for determining frequency/voltage pairings; they're what other OSes use, so maybe you get your 800MHz back then. Please report whether this helps here and/or on cpufreq@www.linux.org.uk

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## sourcez

Great helpful!!!  :Very Happy: 

I have compiled powernow built-in and I add "powernow_k7.powernow_acpi_force=1", "powernow_k7.acpi_force=1" don't work.

Now I get 796,1 Mhz as a minimum freq   :Twisted Evil: 

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## brodo

Can you post the relevant part of dmesg? Thanks.

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## sourcez

Now this is the dmesg output:

```
powernow: PowerNOW! Technology present. Can scale: frequency and voltage.

powernow: FSB: 132.739 MHz

powernow: PSB/PST known to be broken.  Trying ACPI instead

powernow: acpi:  P0: 2000 MHz 75000 mW 125 uS control 00d058f8 SGTC 13334

powernow:    FID: 0x18 (15.0x [1991MHz])        VID: 0x7 (1.650V)

powernow: acpi:  P1: 1800 MHz 60000 mW 125 uS control 00d05915 SGTC 13334

powernow:    FID: 0x15 (13.5x [1791MHz])        VID: 0x8 (1.600V)

powernow: acpi:  P2: 1400 MHz 32000 mW 125 uS control 00d059cf SGTC 13334

powernow:    FID: 0xf (10.5x [1393MHz]) VID: 0xe (1.300V)

powernow: acpi:  P3: 1064 MHz 30000 mW 125 uS control 00d059ca SGTC 13334

powernow:    FID: 0xa (8.0x [1061MHz])  VID: 0xe (1.300V)

powernow: acpi:  P4: 800 MHz 26000 mW 125 uS control 00d059c6 SGTC 13334

powernow:    FID: 0x6 (6.0x [796MHz])   VID: 0xe (1.300V)

powernow: Minimum speed 796 MHz. Maximum speed 1991 MHz.

```

----------

## tbart

same with Acer Aspire 1356LCi, Athlon-XPm 2800+

kernel 2.6.8-gentoo-r3

scaling with BIOS tables only works between 1400 and 2100 MHz.

forcing to ACPI gives the following:

```

powernow: PowerNOW! Technology present. Can scale: frequency and voltage. 

powernow: FSB: 132.718 MHz 

powernow: PSB/PST known to be broken.  Trying ACPI instead 

powernow: acpi:  P0: 2133 MHz 75000 mW 125 uS control 00d058fa SGTC 13334 

powernow:    FID: 0x1a (16.0x [2123MHz])        VID: 0x7 (1.650V) 

powernow: acpi:  P1: 1800 MHz 55000 mW 125 uS control 00d05935 SGTC 13334 

powernow:    FID: 0x15 (13.5x [1791MHz])        VID: 0x9 (1.550V) 

powernow: acpi:  P2: 1467 MHz 32000 mW 125 uS control 00d059c0 SGTC 13334 

powernow:    FID: 0x0 (11.0x [1459MHz]) VID: 0xe (1.300V) 

powernow: acpi:  P3: 1064 MHz 30000 mW 125 uS control 00d059ca SGTC 13334 

powernow:    FID: 0xa (8.0x [1061MHz])  VID: 0xe (1.300V) 

powernow: acpi:  P4: 800 MHz 26000 mW 125 uS control 00d059c6 SGTC 13334 

powernow:    FID: 0x6 (6.0x [796MHz])   VID: 0xe (1.300V) 

powernow: Minimum speed 796 MHz. Maximum speed 2123 MHz.

```

tbart

----------

## tbart

interesting: now with kernel

2.6.10-gentoo-r6

i get this:

```

powernow: PowerNOW! Technology present. Can scale: frequency and voltage.

powernow: PSB/PST known to be broken.  Trying ACPI instead

powernow: Minimum speed 298 MHz. Maximum speed 796 MHz.

```

but scaling works between ~800 and ~2100 MHz as before.

(using cat /proc/cpuinfo)

powersave:

```

AcerGentooBox root # cat /proc/cpuinfo

processor       : 0

vendor_id       : AuthenticAMD

cpu family      : 6

model           : 10

model name      : Mobile AMD Athlon(tm) XP 2800+

stepping        : 0

cpu MHz         : 796.221

cache size      : 512 KB

fdiv_bug        : no

hlt_bug         : no

f00f_bug        : no

coma_bug        : no

fpu             : yes

fpu_exception   : yes

cpuid level     : 1

wp              : yes

flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse pni syscall mp mmxext 3dnowext 3dnow

bogomips        : 1564.67

```

performance:

```

AcerGentooBox root # cat /proc/cpuinfo

processor       : 0

vendor_id       : AuthenticAMD

cpu family      : 6

model           : 10

model name      : Mobile AMD Athlon(tm) XP 2800+

stepping        : 0

cpu MHz         : 2123.256

cache size      : 512 KB

fdiv_bug        : no

hlt_bug         : no

f00f_bug        : no

coma_bug        : no

fpu             : yes

fpu_exception   : yes

cpuid level     : 1

wp              : yes

flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse pni syscall mp mmxext 3dnowext 3dnow

bogomips        : 4172.45

```

...interesting...

but it works, never mind.

th

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## brodo

 *tbart wrote:*   

> interesting: now with kernel
> 
> 2.6.10-gentoo-r6
> 
> i get this:
> ...

 

This is the same bug as reported in http://bugme.osdl.org/show_bug.cgi?id=3600. We're working on it.

----------

