ACPI _PS0 failing with UNINITIALIZED_ARG

[Johannes Kliemann]

Hi,

thanks for your answer. Well the I2C controller is already enabled. I
can successfully run \_SB_.I2C4._PS(0|3). I even can measure the effect
since the magic value in the mmio is only available if _PS0 was called
on the I2C controller.

I have traced the initialization on Linux (exactly said the calls of
evaluate object) and there doesn't seem to be anything unusual.

> \_SB_.I2C4._STA
> \_SB_.I2C4.TCS2._STA
> \_SB_.I2C4.SSCN
> \_SB_.I2C4.FMCN
> \_SB_.I2C4.FPCN
> \_SB_.I2C4.HSCN
> \_SB_.I2C4._STA
> \_SB_.I2C4.TCS2._STA
> \_SB_.I2C4._PS3
> \_SB_.I2C4._STA
> \_SB_.I2C4.TCS2._STA
> \_SB_.I2C4._PS0
> \_SB_.I2C4.TCS2._PS3
> \_SB_.I2C4.TCS2._PS0

This is the sequence called by Linux (shortened, double entries are
omitted). Beside the status calls I can't see anything special.

Regards,
Johannes

Am 04.08.2017 um 11:12 schrieb Alexander Boettcher:
> Hi,
> 
> On 03.08.2017 13:29, Johannes Kliemann wrote:
>>> I have a touchscreen controller (which is an I2C slave) that I need to enable via APCI. This should be done by calling the _PS0 ACPI method. I call this method by using AcpiEvaluateObject with no arguments and no return values.
> 
> just guessing. Since the touchscreen controller is a slave of the I2C
> controller, you have to have a (ACPI) driver to enable the I2C and
> potentially also the right I2C slaves.
> 
>>> what am I missing to successfully enable the touchscreen device via ACPI? Is there something the Linux kernel is initializing implicitly (I couldn't find something like this)?
>>
>> The current workaround for this issue is to use the GPIO pins to enable
>> the controller. But this isn't the desired way since it requires an
>> additional GPIO driver that takes ~100 LOC and also a separate ACPI
>> initialization for this driver.
> 
> again, just guessing. Your workaround sounds bit like a part of the
> initialize sequence of the I2C controller.
> 
>> Besides that other functions that are needed to get initial parameters
>> return errors. On the specific device I have the following examples:
>>
>>> \_SB_.I2C4.SSCN
>>> \_SB_.I2C4.FMCN
>>> \_SB_.I2C4.FPCN
>>> \_SB_.I2C4.HSCN
> 
> again, just guessing. Probably you need/have to find the right acpi
> method to initialize the I2C controller, so that the slaves, as your
> touchscreen, may work properly.
> 
>>> what am I missing to successfully enable the touchscreen device via
> ACPI? Is there something the Linux kernel is initializing implicitly (I
> couldn't find something like this)?
> 
> ... just guessing: the Linux kernel initialize the I2C controller for
> sure fully, thats why the I2C method in the ACPI tables of your I2C
> slave work in Linux ?
> 
> 
> If all my guessing above is wrong, another direction could be to check
> the version of the acpica library used by Genode and the ACPICA version
> you have in the Linux kernel. I know that ACPICA library code and Linux
> code does not exactly match (but they have common roots), so that one
> may possibly deduce the difference in the behavior. Maybe a update to a
> new ACPICA library version for Genode can help (since there a features
> and fixes in the upstream ACPICA library according to the changelog) ?
> 
> Good luck,
>