Re: [PATCH v2 4/9] acpi/gpex: Create PCI link devices outside PCI root bridge

[Igor Mammedov <imammedo@redhat.com>]

On Mon,  8 Jul 2024 17:17:36 +0530
Sunil V L <sunilvl@ventanamicro.com> wrote:

> Currently, PCI link devices (PNP0C0F) are always created within the
> scope of the PCI root bridge. However, RISC-V needs these link devices
> to be created outside to ensure the probing order in the OS. This
> matches the example given in the ACPI specification [1] as well. Hence,
> create these link devices directly under _SB instead of under the PCI
> root bridge.
> 
> To keep these link device names unique for multiple PCI bridges, change
> the device name from GSIx to LXXY format where XX is the PCI bus number
> and Y is the INTx.
> 
> GPEX is currently used by riscv, aarch64/virt and x86/microvm machines.
> So, this change will alter the DSDT for those systems.
> 
> [1] - ACPI 5.1: 6.2.13.1 Example: Using _PRT to Describe PCI IRQ Routing
> 
> Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
> ---
>  hw/pci-host/gpex-acpi.c | 13 +++++++------
>  1 file changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/pci-host/gpex-acpi.c b/hw/pci-host/gpex-acpi.c
> index f69413ea2c..a93b55c991 100644
> --- a/hw/pci-host/gpex-acpi.c
> +++ b/hw/pci-host/gpex-acpi.c
> @@ -7,7 +7,8 @@
>  #include "hw/pci/pcie_host.h"
>  #include "hw/acpi/cxl.h"
>  
> -static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq)
> +static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq,
> +                                          Aml *scope, uint8_t bus_num)
>  {
>      Aml *method, *crs;
>      int i, slot_no;
> @@ -20,7 +21,7 @@ static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq)
>              Aml *pkg = aml_package(4);
>              aml_append(pkg, aml_int((slot_no << 16) | 0xFFFF));
>              aml_append(pkg, aml_int(i));
> -            aml_append(pkg, aml_name("GSI%d", gsi));
> +            aml_append(pkg, aml_name("L%.02X%d", bus_num, gsi));
 instead of mixing hex and decimal here, make gsi hex as well to be consistent?


>              aml_append(pkg, aml_int(0));
>              aml_append(rt_pkg, pkg);
>          }
> @@ -30,7 +31,7 @@ static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq)
>      /* Create GSI link device */
>      for (i = 0; i < PCI_NUM_PINS; i++) {
>          uint32_t irqs = irq + i;
> -        Aml *dev_gsi = aml_device("GSI%d", i);
> +        Aml *dev_gsi = aml_device("L%.02X%d", bus_num, i);
ditto

>          aml_append(dev_gsi, aml_name_decl("_HID", aml_string("PNP0C0F")));
>          aml_append(dev_gsi, aml_name_decl("_UID", aml_int(i)));
>          crs = aml_resource_template();
> @@ -45,7 +46,7 @@ static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq)
>          aml_append(dev_gsi, aml_name_decl("_CRS", crs));
>          method = aml_method("_SRS", 1, AML_NOTSERIALIZED);
>          aml_append(dev_gsi, method);
> -        aml_append(dev, dev_gsi);
> +        aml_append(scope, dev_gsi);
>      }
>  }
>  
> @@ -174,7 +175,7 @@ void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
>                  aml_append(dev, aml_name_decl("_PXM", aml_int(numa_node)));
>              }
>  
> -            acpi_dsdt_add_pci_route_table(dev, cfg->irq);
> +            acpi_dsdt_add_pci_route_table(dev, cfg->irq, scope, bus_num);
>  
>              /*
>               * Resources defined for PXBs are composed of the following parts:
> @@ -205,7 +206,7 @@ void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
>      aml_append(dev, aml_name_decl("_STR", aml_unicode("PCIe 0 Device")));
>      aml_append(dev, aml_name_decl("_CCA", aml_int(1)));
>  
> -    acpi_dsdt_add_pci_route_table(dev, cfg->irq);
> +    acpi_dsdt_add_pci_route_table(dev, cfg->irq, scope, 0);
>  
>      method = aml_method("_CBA", 0, AML_NOTSERIALIZED);
>      aml_append(method, aml_return(aml_int(cfg->ecam.base)));