Re: [PATCH v3 10/15] acpi: parallel: don't use _STA method

[Igor Mammedov <imammedo@redhat.com>]

On Wed, 29 Apr 2020 15:59:58 +0200
Gerd Hoffmann <kraxel@redhat.com> wrote:

> The _STA method dates back to the days where we had a static DSDT.  The
> device is listed in the DSDT table unconditionally and the _STA method
> checks a bit in the isa bridge pci config space to figure whenever a
> given is isa device is present or not, then evaluates to 0x0f (present)
> or 0x00 (absent).
> 
> These days the DSDT is generated by qemu anyway, so if a device is not
> present we can simply drop it from the DSDT instead.
> 
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> Reviewed-by: Igor Mammedov <imammedo@redhat.com>

looking more at it, we should also cleanup no longer used LPEN field
the same applies to similar fields for serial and ... 


> ---
>  hw/i386/acpi-build.c | 29 ++++++++---------------------
>  1 file changed, 8 insertions(+), 21 deletions(-)
> 
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index fea83352e6ab..e01afbd011d9 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -1167,39 +1167,26 @@ static Aml *build_mouse_device_aml(void)
>      return dev;
>  }
>  
> -static Aml *build_lpt_device_aml(void)
> +static void build_lpt_device_aml(Aml *scope)
>  {
>      Aml *dev;
>      Aml *crs;
> -    Aml *method;
> -    Aml *if_ctx;
> -    Aml *else_ctx;
> -    Aml *zero = aml_int(0);
> -    Aml *is_present = aml_local(0);
> +
> +    if (!memory_region_present(get_system_io(), 0x0378)) {
> +        return;
> +    }
>  
>      dev = aml_device("LPT");
>      aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0400")));
>  
> -    method = aml_method("_STA", 0, AML_NOTSERIALIZED);
> -    aml_append(method, aml_store(aml_name("LPEN"), is_present));
> -    if_ctx = aml_if(aml_equal(is_present, zero));
> -    {
> -        aml_append(if_ctx, aml_return(aml_int(0x00)));
> -    }
> -    aml_append(method, if_ctx);
> -    else_ctx = aml_else();
> -    {
> -        aml_append(else_ctx, aml_return(aml_int(0x0f)));
> -    }
> -    aml_append(method, else_ctx);
> -    aml_append(dev, method);
> +    aml_append(dev, aml_name_decl("_STA", aml_int(0xf)));
>  
>      crs = aml_resource_template();
>      aml_append(crs, aml_io(AML_DECODE16, 0x0378, 0x0378, 0x08, 0x08));
>      aml_append(crs, aml_irq_no_flags(7));
>      aml_append(dev, aml_name_decl("_CRS", crs));
>  
> -    return dev;
> +    aml_append(scope, dev);
>  }
>  
>  static void build_isa_devices_aml(Aml *table)
> @@ -1215,7 +1202,7 @@ static void build_isa_devices_aml(Aml *table)
>      if (fdc) {
>          aml_append(scope, build_fdc_device_aml(fdc));
>      }
> -    aml_append(scope, build_lpt_device_aml());
> +    build_lpt_device_aml(scope);
>  
>      if (ambiguous) {
>          error_report("Multiple ISA busses, unable to define IPMI ACPI data");