[U-Boot] [PATCH 03/10] dm: pci: Allow a PCI bus to be found without an alias

[Bin Meng]

Hi Simon,

On Thu, Aug 13, 2015 at 10:09 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>
> ---
>
>  drivers/pci/pci-uclass.c | 22 +++++++++++++++++++---
>  1 file changed, 19 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/pci-uclass.c b/drivers/pci/pci-uclass.c
> index 7d41d56..a72e297 100644
> --- a/drivers/pci/pci-uclass.c
> +++ b/drivers/pci/pci-uclass.c
> @@ -17,6 +17,22 @@
>
>  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 && !busnum) {

We should remove !busnum as it is possible to read configuration
registers that are not on bus 0.

> +               ret = uclass_first_device(UCLASS_PCI, busp);
> +               if (!ret && (*busp)->seq != busnum)

The test of (*busp)->seq has the assumption that busnum should be 0,
however it is not always the case.

> +                       return -ENODEV;
> +       }
> +
> +       return ret;
> +}
> +
>  struct pci_controller *pci_bus_to_hose(int busnum)
>  {
>         struct udevice *bus;
> @@ -125,7 +141,7 @@ 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);
> @@ -203,7 +219,7 @@ 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;
>
> @@ -268,7 +284,7 @@ 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;
>
> --

Regards,
Bin