[Devel] Re: Question about ACPICA, QNX and making beeps

[Devin Steffler <devinsteffler at gmail.com>]

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Hi Rudolf,

I have the ACPI utilities working in QNX as well (i.e. acpidump,
acpixtract, iasl, etc). The problem is I don't know what to look for in the
FADT.

So far I have only seen this happen on Lenovo based x86 PCs. For example,
the one that I have on hand is a Lenovo ThinkBook 14 Gen 2 laptop. If I
boot the ThinkBook into QNX, then I can play a beep over the PC speaker
just fine. However, after running ACPICA, then I can no longer play a beep
over the PC speaker anymore on this device.

How can I check for 8254 clock gating?

delay is a QNX call to sleep for the specified time in ms.

Thanks,
Devin

On Wed, Sep 29, 2021 at 3:58 PM Rudolf Marek <r.marek(a)assembler.cz> wrote:

> Hi Devin,
>
> Dne 28. 09. 21 v 21:04 Devin Steffler napsal(a):
>
> Hello,
>
> I am using ACPICA to read battery information in QNX. That part is working
> great so far. However, now some code that is being used to make beeps via
> the PC speaker stopped working.
>
> Strangely, this code stops working on a few devices only after ACPICA runs.
>
> You mean same device with same mainboard / BIOS version?
>
> Maybe SMI and/or ACPI bytecode turns on 8254 clock gating? You can
>
> try to disassemble the ACPI DSDT/SSDT bytecode and look for it.
>
> What you can also do, is to try out to send ACPI enable SMI command without
>
> enabling ACPICA and see if it breaks. You can read the I/O port address
>
> and data enable command from FADT. To disassemble the ACPI tables
>
> use acpidump acpixtract and iasl utillites in linux.
>
> What could my ACPICA be doing (or failing to do) that could cause the beeps
> to stop working with the code below? Is the PIT being disabled somehow? I
> guess I'll need to learn more about the PIT and how to check its status to
> see if it's being disabled after ACPICA runs.
>
> Here's example code for QNX to generate a beep using the PC speaker:
> // -----------------------------------------------
> #include <sys/neutrino.h>
> #include <hw/inout.h>
> #include <unistd.h>
>
> int main(void) {
>     ThreadCtl( _NTO_TCTL_IO, 0 ); // get I/O permissions
>
>     // start a beep
>     int freq = 1000;
>     int scale = 1193046 / freq;
>     out8(0x43, 0xb6);
>     out8(0x42, scale & 0xff);
>     out8(0x42, scale >> 8);
>     out8(0x61, in8(0x61) | 3);
>
> you can also try to see if your assembly for out8 is correct and maybe not
> re-ordered
>
> by the compiler or that your asm clobber list is correct (same for in8)
>
>
>     // let the beep play for a second
>     delay(1000);
>
> delay is an OS service right?
>
> Thanks,
>
> Rudolf
>

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