Re: [SeaBIOS] [PATCH v2 3/3] pci: recognize RH PCI legacy bridge resource reservation capability

[Liu, Jing2]

Hi Zihan,

I copy your comments of this patch several days ago here,
and hope we could continue some discussion in this serial.

On 8/16/2018 10:32 AM, Jing Liu wrote:
[...]
> static u8 pci_find_resource_reserve_capability(u16 bdf)
>   {
> if (pci_config_readw(bdf, PCI_VENDOR_ID) == PCI_VENDOR_ID_REDHAT &&
>    pci_config_readw(bdf, PCI_DEVICE_ID) ==
>            PCI_DEVICE_ID_REDHAT_ROOT_PORT) {
>    u8 cap = 0;
>    do {
>        cap = pci_find_capability(bdf, PCI_CAP_ID_VNDR, cap);
>    } while (cap &&
>             pci_config_readb(bdf, cap + PCI_CAP_REDHAT_TYPE_OFFSET) !=
>                    REDHAT_CAP_RESOURCE_RESERVE);
>    if (cap) {
>        u8 cap_len = pci_config_readb(bdf, cap + PCI_CAP_FLAGS);
>        if (cap_len < RES_RESERVE_CAP_SIZE) {
>            dprintf(1, "PCI: QEMU resource reserve cap length %d is invalid\n",
>                    cap_len);
>            return 0;
>        }
>    } else {
>        dprintf(1, "PCI: QEMU resource reserve cap not found\n");
> u16 device_id;
> if (pci_config_readw(bdf, PCI_VENDOR_ID) != PCI_VENDOR_ID_REDHAT) {
>    dprintf(1, "PCI: QEMU resource reserve cap vendor ID doesn't match.\n");
>    return 0;
> }
> device_id = pci_config_readw(bdf, PCI_DEVICE_ID);
> if (device_id != PCI_DEVICE_ID_REDHAT_ROOT_PORT &&
>    device_id != PCI_DEVICE_ID_REDHAT_BRIDGE) {

======= comments by Zihan Yang =========
I think PCI_DEVICE_ID_REDHAT_PCIE_BRIDGE shoud be added too, in case we put
a pcie_pci_bridge at the host bus.
========================================
My reply:
In theory all the pci bridge could add this capability but I'm not sure
if we really need that? Would like to hear some more suggestion!

Thanks,
Jing

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