Re: Add a SSDT ACPI description to recognize my I2C device connected via SMBus

[Florian Eckert <fe@dev.tdt.de>]

> The mcp23s08 can not be connected to I2C. It's a SPI device.
> Which chip do you actually have? I believe it's MCP23017 or MCP23018,
> which is I2C.

Yes the device is a mcp23017, but the driver is the pinctrl_mcp23s08 [1]

root@dev ~ # lsmod | grep mcp
pinctrl_mcp23s08       16384  0
regmap_core            45056  1 pinctrl_mcp23s08,[permanent]

> Summary:
> 1) _CID notation is wrong in ASL;

I got it

> 2) driver seems supports the _ADR schema which you have used in ASL;

This refers to the i2c-0, doesn't it?
My mcp23s08 device is located at the i2c-0 on address 0x24.

> 3) something fishy about I/O addresses in the sysfs (is it a typo when
> you composed the email?);

No

I have asked myself the same question.
Something is not right.
There was a change regarding the Hudson2 in the driver, maybe something 
went wrong [2]?

> 4) it's unclear what you did with ASL to get it loaded;

On my development device I did a `iasl dsl/mcp23017.dsl`
Of the following dsl

$ cat dsl/mcp23017.dsl
DefinitionBlock ("mcp23017.aml", "SSDT", 5, "", "MCP23017", 4)
{
     External (\_SB.PCI0.SBUS, DeviceObj)

     Scope (\_SB.PCI0.SBUS)
     {
         Device (GPIO)
         {
             Name (_HID, "PRP0001")
             Name (_DDN, "MCP23017 gpio expander")
             Name (_ADR, Zero)
             Name (_CRS, ResourceTemplate () {
                 I2cSerialBus (
                     0x24,                   // Bus address
                     ControllerInitiated,    // Don't care
                     400000,                 // Fast mode (400 kHz)
                     AddressingMode7Bit,     // 7-bit addressing
                     "\\_SB.PCI0.SBUS",      // I2C host controller
                     0                       // Must be 0
                 )
             })

             Name (_DSD, Package () {
                 ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
                 Package () {
                     Package () { "compatible", Package () { 
"microchip,mcp23017" } },
                 }
             })
         }
     }
}

After that I copied this to my APU3 Target and executed
  the following commands:
mkdir /sys/kernel/config/acpi/table/mcp23017

cat mcp23s08.aml > /sys/kernel/config/table/mcp23017

> 5) as Mika suggested, have you checked the kernel configuration?

I have now switched on the suggested option
CONFIG_ACPI_CUSTOM_METHOD=y
CONFIG_ACPI_TABLE_UPGRADE=y
CONFIG_CONFIGFS_FS=y
CONFIG_ACPI_CONFIGFS=y
CONFIG_ACPI_DEBUG=y

But this did not solved my issue loading ssdt during runtime.

The output of the aml on the target:

cat /sys/kernel/config/acpi/table/mcp23017/aml
SSDTsMCP23017INTL \/_SB_PCI0SBUSK
                                  \/_SB_PCI0SBUS[H
MCP23017 gpio expande_AD_CRS&
#$\_SB.PCI0.SBUS_DSD?
microchip,mcp23017


My iasl version:

iasl --version
Illegal option: --

Intel ACPI Component Architecture
ASL+ Optimizing Compiler/Disassembler version 20181213
Copyright (c) 2000 - 2018 Intel Corporation


What else can I do?
The initrd option does not work with OpenWrt.
Maybe I can get further if you can give me a good HEX for debug_level 
and the debug_layer?

---
Regards Florian

[1] 
https://github.com/torvalds/linux/blob/master/drivers/pinctrl/pinctrl-mcp23s08_i2c.c
[2] 
https://github.com/torvalds/linux/commit/528d53a1592b0e27c423f7cafc1df85f77fc1163#diff-aa95f6311d1fcc4d85955b153a2510e853807546ac8e0d3aa0310ac30d236147