Hi Fabio,
On 9 October 2015 at 14:22, Fabio Estevam <feste...@gmail.com> wrote:
> Hi Simon,
>
> On Fri, Oct 9, 2015 at 10:01 AM, Simon Glass <s...@chromium.org> wrote:
>
>> I'm just surprised that it is failing when there is nothing there. I
>> think it should succeed (and read 0xffff).
>>
>> What board is this? Can you find the code that is returning this
>> error? It may be a call to pci_set_ops() which sets read_word().
>
> It is a mx6qsabresd board.
>
> I don't have the PCI device at the moment to give it a try, but
> looking at the code, in pcie_imx we have:
>
> pci_set_ops(hose,
> pci_hose_read_config_byte_via_dword,
> pci_hose_read_config_word_via_dword,
> imx_pcie_read_config,
> pci_hose_write_config_byte_via_dword,
> pci_hose_write_config_word_via_dword,
> imx_pcie_write_config);
>
> Then in drivers/pci/pci.c:
>
> #define PCI_READ_VIA_DWORD_OP(size, type, off_mask) \
> int pci_hose_read_config_##size##_via_dword(struct pci_controller *hose,\
> pci_dev_t dev, \
> int offset, type val) \
> { \
> u32 val32; \
> \
> if (pci_hose_read_config_dword(hose, dev, offset & 0xfc, &val32) < 0) {
> \
> *val = -1; \
> return -1; \
> } \
> \
> *val = (val32 >> ((offset & (int)off_mask) * 8)); \
> \
> return 0; \
> }
>
> ,which returns -1 (and also *val = -1) in the case of errror, which
> matches the values that I was reading yesterday
If you look down one more level, these end up calling
imx_pcie_read_config() which calls imx_pcie_addr_valid():
static int imx_pcie_addr_valid(pci_dev_t d)
{
if ((PCI_BUS(d) == 0) && (PCI_DEV(d) > 1))
return -EINVAL;
if ((PCI_BUS(d) == 1) && (PCI_DEV(d) > 0))
return -EINVAL;
return 0;
}
I can understand the bus check, but why return an access error if the
device does not exist on the bus? That seems like a bug to me.
Regards,
Simon
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