[U-Boot] [PATCH v2 2/9] dm: pci: Allow a PCI bus to be found without an alias

[Bin Meng]

Hi Simon,

On Sun, Aug 23, 2015 at 5:58 AM, Simon Glass <sjg at chromium.org> wrote:
> At present, until a PCI bus is probed, it cannot be found by its sequence
> number unless it has an alias. This is the same with any device.
>
> However with PCI this is more annoying than usual, since bus 0 is always the
> same device.
>
> Add a function that tries a little harder to locate PCI bus 0. This means
> that PCI enumeration will happen automatically on the first access.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
> Changes in v2:
> - Adjust pci_get_bus() to probe bus 0 so that the required bus is found
>
>  drivers/pci/pci-uclass.c | 23 ++++++++++++++++++++---
>  1 file changed, 20 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/pci-uclass.c b/drivers/pci/pci-uclass.c
> index c90e7ac..ca47dc3 100644
> --- a/drivers/pci/pci-uclass.c
> +++ b/drivers/pci/pci-uclass.c
> @@ -20,6 +20,23 @@
>
>  DECLARE_GLOBAL_DATA_PTR;
>
> +static int pci_get_bus(int busnum, struct udevice **busp)
> +{
> +       int ret;
> +
> +       ret = uclass_get_device_by_seq(UCLASS_PCI, busnum, busp);
> +
> +       /* Since buses may not be numbered yet try a little harder with bus 0 */
> +       if (ret == -ENODEV) {
> +               ret = uclass_first_device(UCLASS_PCI, busp);
> +               if (!ret)

By looking at the API comments of uclass_first_device(), I think this
logic should be:

    if (ret || ((!ret) && (!*busp)))

> +                       return -ENODEV;
> +               ret = uclass_get_device_by_seq(UCLASS_PCI, busnum, busp);
> +       }
> +
> +       return ret;
> +}
> +
>  struct pci_controller *pci_bus_to_hose(int busnum)
>  {
>         struct udevice *bus;
> @@ -128,7 +145,7 @@ int pci_bus_find_bdf(pci_dev_t bdf, struct udevice **devp)
>         struct udevice *bus;
>         int ret;
>
> -       ret = uclass_get_device_by_seq(UCLASS_PCI, PCI_BUS(bdf), &bus);
> +       ret = pci_get_bus(PCI_BUS(bdf), &bus);
>         if (ret)
>                 return ret;
>         return pci_bus_find_devfn(bus, PCI_MASK_BUS(bdf), devp);
> @@ -206,7 +223,7 @@ int pci_write_config(pci_dev_t bdf, int offset, unsigned long value,
>         struct udevice *bus;
>         int ret;
>
> -       ret = uclass_get_device_by_seq(UCLASS_PCI, PCI_BUS(bdf), &bus);
> +       ret = pci_get_bus(PCI_BUS(bdf), &bus);
>         if (ret)
>                 return ret;
>
> @@ -271,7 +288,7 @@ int pci_read_config(pci_dev_t bdf, int offset, unsigned long *valuep,
>         struct udevice *bus;
>         int ret;
>
> -       ret = uclass_get_device_by_seq(UCLASS_PCI, PCI_BUS(bdf), &bus);
> +       ret = pci_get_bus(PCI_BUS(bdf), &bus);
>         if (ret)
>                 return ret;
>
> --

I think we need also update pci_bus_to_hose() to use pci_get_bus()
instead of calling uclass_get_device_by_seq().

Regards,
Bin