Re: [edk2-devel] [PATCH edk2-platforms WIP 0/5] Provide EHCI or XHCI USB controller

["Marcin Juszkiewicz" <marcin.juszkiewicz@linaro.org>]

W dniu 13.10.2023 o 15:31, Marcin Juszkiewicz via groups.io pisze:
> W dniu 13.10.2023 o 15:24, Gerd Hoffmann pisze:
> 
>>> So two solutions came to my mind:
>>>
>>> 1. rewrite DSDT generation into C
>>
>> You might want have a look at DynamicTablesPkg/ for that
> 
> Wasn't is involving using ConfigurationManager? Or maybe I just had 
> wrong assumption after reading code.

>>> 2. provide EHCI/XHCI in SSDT table instead of DSDT
>>
>> Should work, except that I'd suggest to worry about xhci only.
>> ehci never actually worked anyway, so why advertise it to the OS in the
>> first place?
> 
> Good point.

Got rid of EHCI at all. On >= 0.3 XHCI is created, otherwise there is no 
USB controller in DSDT.

>> 3. Add a _STA AML function to the XHCI DSDT description, which is able
>> to figure whenever XHCI is present.
>>
>> We had that in qemu years ago, before switching to full DSDT generation,
>> where the _STA functions checked some bit in PCI config space of the ISA
>> bridge to figure whenever specific isa devices (floppy, serial/parallel
>> port) are present or not.

> Will look.

Our XHCI is on sysbus so checking PCI_config is not an option.


4. Add variable in ASL + check in _STA for it. And alter that variable 
from C code once DSDT is done. Kind of what Ampere does in 
JadePkg/**/AcpiDsdt.c file.


I am also thinking of going back to 2nd version and handle it on 
ExitBootServicesEvent event (again: Ampere/JadePkg). All ACPI tables 
should be ready at that moment...



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