Re: [RFC 08/24] hw/pci-host/gpex-acpi: Split host bridge OSC and DSM generation

[Gustavo Romero <gustavo.romero@linaro.org>]

Hi Eric,

On 4/28/25 07:25, Eric Auger wrote:
> acpi_dsdt_add_pci_osc() name is confusing as it gives the impression
> it appends the _OSC method but in fact it also appends the _DSM method
> for the host bridge. Let's split the function into two separate ones
> and let them return the method Aml pointer instead. This matches the
> way it is done on x86 (build_q35_osc_method). In a subsequent patch
> we will replace the gpex method by the q35 implementation that will
> become shared between ARM and x86.
> 
> acpi_dsdt_add_host_bridge_methods is a new top helper that generates
> both the _OSC and _DSM methods.
> 
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> ---
>   hw/pci-host/gpex-acpi.c | 31 +++++++++++++++++++++----------
>   1 file changed, 21 insertions(+), 10 deletions(-)
> 
> diff --git a/hw/pci-host/gpex-acpi.c b/hw/pci-host/gpex-acpi.c
> index 4016089893..9d9f5ed7c6 100644
> --- a/hw/pci-host/gpex-acpi.c
> +++ b/hw/pci-host/gpex-acpi.c
> @@ -50,13 +50,10 @@ static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq,
>       }
>   }
>   
> -static void acpi_dsdt_add_pci_osc(Aml *dev, bool enable_native_pcie_hotplug)
> +static Aml *build_host_bridge_osc(bool enable_native_pcie_hotplug)
>   {
> -    Aml *method, *UUID, *ifctx, *ifctx1, *elsectx, *buf;
> +    Aml *method, *UUID, *ifctx, *ifctx1, *elsectx;
>   
> -    /* Declare an _OSC (OS Control Handoff) method */
> -    aml_append(dev, aml_name_decl("SUPP", aml_int(0)));
> -    aml_append(dev, aml_name_decl("CTRL", aml_int(0)));
>       method = aml_method("_OSC", 4, AML_NOTSERIALIZED);
>       aml_append(method,
>           aml_create_dword_field(aml_arg(3), aml_int(0), "CDW1"));
> @@ -103,9 +100,13 @@ static void acpi_dsdt_add_pci_osc(Aml *dev, bool enable_native_pcie_hotplug)
>                                  aml_name("CDW1")));
>       aml_append(elsectx, aml_return(aml_arg(3)));
>       aml_append(method, elsectx);
> -    aml_append(dev, method);
> +    return method;
> +}
>   
> -    method = aml_method("_DSM", 4, AML_NOTSERIALIZED);
> +static Aml *build_host_bridge_dsm(void)
> +{
> +    Aml *method = aml_method("_DSM", 4, AML_NOTSERIALIZED);
> +    Aml *UUID, *ifctx, *ifctx1, *buf;
>   
>       /* PCI Firmware Specification 3.0
>        * 4.6.1. _DSM for PCI Express Slot Information
> @@ -124,7 +125,17 @@ static void acpi_dsdt_add_pci_osc(Aml *dev, bool enable_native_pcie_hotplug)
>       byte_list[0] = 0;
>       buf = aml_buffer(1, byte_list);
>       aml_append(method, aml_return(buf));
> -    aml_append(dev, method);
> +    return method;
> +}
> +
> +static void acpi_dsdt_add_host_bridge_methods(Aml *dev,
> +                                              bool enable_native_pcie_hotplug)
> +{
> +    aml_append(dev, aml_name_decl("SUPP", aml_int(0)));
> +    aml_append(dev, aml_name_decl("CTRL", aml_int(0)));
> +    /* Declare an _OSC (OS Control Handoff) method */
> +    aml_append(dev, build_host_bridge_osc(enable_native_pcie_hotplug));
> +    aml_append(dev, build_host_bridge_dsm());
>   }
>   
>   void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
> @@ -193,7 +204,7 @@ void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
>               if (is_cxl) {
>                   build_cxl_osc_method(dev);
>               } else {
> -                acpi_dsdt_add_pci_osc(dev, true);
> +                acpi_dsdt_add_host_bridge_methods(dev, true);
>               }
>   
>               aml_append(scope, dev);
> @@ -268,7 +279,7 @@ void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
>       }
>       aml_append(dev, aml_name_decl("_CRS", rbuf));
>   
> -    acpi_dsdt_add_pci_osc(dev, true);
> +    acpi_dsdt_add_host_bridge_methods(dev, true);
>   
>       Aml *dev_res0 = aml_device("%s", "RES0");
>       aml_append(dev_res0, aml_name_decl("_HID", aml_string("PNP0C02")));

Reviewed-by: Gustavo Romero <gustavo.romero@linaro.org>


Cheers,
Gustavo