[PATCH u-boot] dm: pci: Fix handling of errors when scanning device

[Bin Meng]

On Wed, Sep 8, 2021 at 12:07 AM Marek Behún <marek.behun at nic.cz> wrote:
>
> From: Pali Rohár <pali at kernel.org>
>
> Some PCIe controller's read_config() method support indicating error
> directly via return value, but some cannot distinguish all-ones (or
> all-zeros) read response from an error.
>
> The current code in pci_bind_bus_devices() interprets all-ones /
> all-zeros in PCI_VENDOR_ID register as "nothing connected", and
> continues the cycle, but an error returned via return value breaks the
> cycle.
>
> This is wrong for the PCIe controllers which return this error via
> return value.
>
> Handle all errors when reading PCI_VENDOR_ID the same way.
>
> This fixes enumeration of PCI devices for example when there is a PCI
> bridge connected behind another PCI bridge and not all ports are
> connected to a device, and the controller (for example Aardvark)
> translates the UR error (Unsupported Request) as -EOPNOTSUPP.
>
> Signed-off-by: Pali Rohár <pali at kernel.org>
> Signed-off-by: Marek Behún <marek.behun at nic.cz>
> ---
>  drivers/pci/pci-uclass.c | 9 +--------
>  1 file changed, 1 insertion(+), 8 deletions(-)
>

Is it possible to update these PCI controller drivers to fill in
vendor id to all zeros when there is an errror?

Regards,
Bin