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Re: Stability Under Load

 

On 08/21/2011 06:50 PM, Julian Andres Klode wrote:
On Sun, Aug 21, 2011 at 01:09:09PM +0100, Gordan Bobic wrote:
On 08/21/2011 12:27 PM, Julian Andres Klode wrote:
On Sun, Aug 21, 2011 at 12:06:39PM +0100, Gordan Bobic wrote:
Really? It complains about a max of 1000mV? On my AC100 975mV and
above produces no error. What model did you say you have?
Yes, a 10V. It should be fairly obvious the cpu_millivolts in
tegra2_dvfs.c includes 1100, the default level is 1100, as can
be seen in cpu_speedo_max_millivolts array, and
tegra2_dvfs_rail_vdd_cpu.

Hmm, that's interesting. So how do the differences between what's in
tegra2_dvfs.c and what's in board-paz00-power.c get reconciled?
Aren't these settings redundant?

I'm also curious how come my powertop is showing 1000MHz with no
errors in the log when I set SM1 to 975mV.
Buggy powertop? The 1000 MHz is linked to 1100 mV in the DVFS
code, I annotated the following cpu frequency table with the
corresponding voltages.

	{ 0, 216000 },	/*  750 mV */
	{ 1, 312000 },	/*  800 mV */
	{ 2, 456000 },	/*  850 mV */
	{ 3, 608000 },	/*  900 mV */
	{ 4, 760000 },	/*  950 mV */
	{ 5, 816000 },	/* 1000 mV */
	{ 6, 912000 },	/* 1050 mV */
	{ 7, 1000000 },	/* 1100 mV */

There is no way that I can see how you would be able to get
to 1 GHz @ 1 V without also modifying the corresponding
tables in tegra2_dvfs.c:

	static const int cpu_millivolts[MAX_DVFS_FREQS] =
		{750, 775, 800, 825, 850, 875, 900, 925, 950, 975, 1000, 1025, 1050, 1100, 1125};

Given my observations in a previous email, I made some assumptions and changed this array to the following:

static const int cpu_millivolts[MAX_DVFS_FREQS] =
{850, 850, 850, 900, 1000, 1000, 1050, 1050, 1100, 1100, 1100, 1100, 1100, 1100, 1100};

The idea was that if I am seeing the following with the default values:

216MHz -> 750mV
312MHz -> 750mV
456MHz -> 750mV
608MHz -> 825mV
760MHz -> 875mV
816MHz -> 875mV
912MHz -> 925mV
1000MHz -> 975mV

I could adjust those voltage values to what I want them to be.

Unfortunately, that renders the kernel unbootable. Can't see any output on the screen. Any idea as to why that might be happening?

Gordan


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