[U-Boot] PCI: Cannot read bus configuration

[Fabio Estevam]

On Wed, Oct 7, 2015 at 8:07 PM, Fabio Estevam <festevam at gmail.com> wrote:
> Hi Simon,
>
> On Wed, Oct 7, 2015 at 7:30 PM, Simon Glass <sjg at chromium.org> wrote:
>
>> This added error checking to pci_read_config_word(). It might be worth
>> looking at why the access is failing.
>
> I noticed that when VendorID !=0xffff  then pci_read_config_word() returns 0.
>
> In the case when VendorID ==0xffff then it returns -1.
>
> If I do like this:
>
> --- a/common/cmd_pci.c
> +++ b/common/cmd_pci.c
> @@ -77,7 +77,7 @@ void pciinfo(int BusNum, int ShortPCIListing)
>
>                         ret = pci_read_config_word(dev, PCI_VENDOR_ID,
>                                                    &VendorID);
> -                       if (ret)
> +                       if (ret && (VendorID != 0xFFFF))
>                                 goto error;
>                         if ((VendorID == 0xFFFF) || (VendorID == 0x0000))
>                                 continue;
>
> Then the error message is not printed.
>
> Not familiar with the PCI code, so any suggestions are welcome.

If I read the code right it seems that in this loop all the PCI
devices will be scanned.

When no more devices are found then pci_read_config_word() returns -1
and VendoID == 0xffff.

Maybe all we need to do is to filter the error message like this:

--- a/common/cmd_pci.c
+++ b/common/cmd_pci.c
@@ -100,7 +100,8 @@ void pciinfo(int BusNum, int ShortPCIListing)

        return;
 error:
-       printf("Cannot read bus configuration: %d\n", ret);
+       if (VendorID != 0xFFFF)
+               printf("Cannot read bus configuration: %d\n", ret);
 }

Makes sense?

Thanks