Compaq Evo N610c in almost perfect ACPI support shocker

I've just received a Compaq Evo N610c which I wanted to put Linux on. I'd previously owned a Presario 2701ea which had a buggy DSDT (usual off by one errors etc) so was expecting a bit of a bumpy ride.

Kudos to HP/Compaq though, the new BIOS runs almost flawlessly through Linux's ACPI and the only errors on boot seem to be on the interpreter side (although I'd love to be proved wrong ;)

One of the problems seems to be long standing - I found a kludge on the mailing list to fix it:

            Method (C051, 4, NotSerialized)
            {

// Copy Arg1 pointer to Local2 (in theory)
Store (Arg1, Local2)
Store (Arg3, Local4)
Add (Local4, 0x1A, Local5)
While (LLess (Local4, Local5))
{
Store (DerefOf (Index (C04F, Local4)), Index (Arg0,
Local2))
Increment (Local4)
// Nasty side-effect, also increments Arg1

                    Increment (Local2)
                }

// Let's reset Local2 to Arg1 again.. oh dear it's the same value.
// Store (Arg1, Local2)
// Here comes the kludge

                Subtract (Local2, 0x1A, Local2)
// This was making it go past end of buffer
                Add (Local2, 0x0A, Local2)

As you can see I've applied the Subtract kludge other people have used, but there's nothing actually wrong with the ASL here AFAICS, it should work.

The other part may just be ACPI being over-verbose on something it's handling correctly - I don't think I'm losing any functionality because of it:

ACPI-1121: *** Error: Method execution failed
[\_SB_.C045.C059.C0E2.C13F] (N
ode cff95e40), AE_AML_UNINITIALIZED_LOCAL
ACPI-1121: *** Error: Method execution failed
[\_SB_.C045.C059.C0E2.C14E] (N
ode cff931c0), AE_AML_UNINITIALIZED_LOCAL

    ACPI-1121: *** Error: Method execution failed [\_SB_.C198._BTP]

(Node cff8ec
80), AE_AML_UNINITIALIZED_LOCAL
ACPI: Battery Slot [C198] (battery present)

Here's the DSDT snippet:

                    Method (C13F, 3, Serialized)
                    {
                        Add (Arg2, 0x01, Local3)
                        Store (Buffer (Local3)
                            {
                                0x10
                            }, Local2)
                        Store (0x0A, Local5)
                        Store (0x01, Local1)
// This next line has been added by me to satisfy the parser
						Store (0x00, Local0)

                        While (LAnd (Local1, LGreater (Local5, 0x00)))
                        {
                            Store (C12E (0x00), Local1)
                            If (LNot (Local1))
                            {
                                Store (C12D (Arg0, Arg1), Local1)
                                If (LAnd (LNot (Local1), LGreater (Arg2,
0x00)))
                                {
                                    Store (C12C (Arg0, Arg2), Local0)
                                    Store (DerefOf (Index (Local0,
0x00)), Local
1)
                                }

                                Or (C12F (), Local1, Local1)
                            }

                            Decrement (Local5)
                            If (LAnd (Local1, LGreater (Local5, 0x00)))
                            {
                                Sleep (0x64)
                            }
                        }

                        If (Local1)
                        {
                            Return (Local2)
                        }

// Not initialised if the While loop isn't entered, but if that's the // case then Local1 is true (1) and this point is not reached.

                        Return (Local0)
                    }

With the kludge I apply above, there are no errors during boot.

Now, onto the HP/Compaq problem I've found (where do I apply for a ROMPAQ?) There are only two settings for Intel Speedstep in the BIOS (fine thought I) Auto and Disabled. Disabled, as expected, disables the Speedstep functionality and you see <Not Supported> in processor...performance. Good so far.

Auto means that the laptop fully controls the Speedstep functionality and it cannot be overridden by the OS. I've tested this by installing CPUFREQ which accesses speedstep outside of ACPI, configuring it for 60%60%powersave and when running glxgears I get a jump up to the same FPS I get on 100%100%performance. I can confirm this for several seconds afterward with cat /proc/sys/cpu/0/speed showing the maximum cpu speed. ACPI is not being informed of the processor state changes and shows P0: regardless of which P state the laptop is in.

I've just tagged this on because I know there are a few HP/Compaq people on here and I hope they'll be able to provide a ROMPAQ which at least exposes "Enabled" or "OS" which would allow the OS to control the speedstep state (or at least point me in the right direction) It may also help others who are currently baffled by the behaviour :)

It's currently running F15A BIOS, which appears to be the latest available on the site.

I'd like to finish by saying that this is the best Compaq laptop I've ever had and I believe that I have every piece of hardware working on it (modem unnecessary and untested). I'd definitely recommend it to the company I work for if the Speedstep issue can be resolved.

I'll have the usual stuff up on my website when I get around to it :) (actually precious little because everything is so well supported!) but in the meantime:

An error free dmesg:
http://dude.noc.clara.net/~faye/evo_n610c/dmesg.txt
The F15A dsdt:
http://dude.noc.clara.net/~faye/evo_n610c/dsdt
The patched dsdt:
http://dude.noc.clara.net/~faye/evo_n610c/dsdt.dsl

I'm going to be moving the site to http://www.zippysoft.com/linux/
some time in the near future.

Faye

Faye Pearson,
Covert Development
ClaraNET Ltd.       Tel 020 7903 3000

Of all the animals, the boy is the most unmanageable.
		-- Plato


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Ah yes. That seems funny. I wasn't aware for that.

I don't have fully looked the while loop, but it seems for me you can have Local0 not initialised, but Local1 contains 0.

I don't understand the cpufreq trouble. But my english is bad... What cpufreq driver are you using btw (the ich or the newer smi one?).

the smi should work like you want (that is no speedstep if you disable it), but the ich one talk directly to the hardware, regardless of what 'think' bios.
And, (but that may change soon), acpi performance and cpufreq have diferent API, so no, if you are using acpi P-state and cpufreq at the same time, then only weird things, confusions about the 2 way happens (that is true *only* for the 2.4 kernel, not for 2.6).

Ducrot Bruno

--  Which is worse:  ignorance or apathy?
--  Don't know.  Don't care.


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