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dm/pci: Change the first CFG read to Vendor ID in enumeration

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As the PCIe specification recommend reading the Vendor ID register
to determine if a Function is present, read the Vendor ID of a
non-existent Function must not result in system error, so we'd better
make the first CFG read to Vendor ID instead of Header Type register
in the PCIe enumeration.

Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
This commit is contained in:
Hou Zhiqiang 2018-10-08 16:35:47 +08:00 committed by Simon Glass
parent a3e1653dde
commit 2a87f7fdd5
1 changed files with 7 additions and 4 deletions
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11
drivers/pci/pci-uclass.c
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@ -774,16 +774,19 @@ int pci_bind_bus_devices(struct udevice *bus)
found_multi = false;
if (PCI_FUNC(bdf) && !found_multi)
continue;
/* Check only the first access, we don't expect problems */
ret = pci_bus_read_config(bus, bdf, PCI_HEADER_TYPE,
&header_type, PCI_SIZE_8);
ret = pci_bus_read_config(bus, bdf, PCI_VENDOR_ID, &vendor,
PCI_SIZE_16);
if (ret)
goto error;
pci_bus_read_config(bus, bdf, PCI_VENDOR_ID, &vendor,
PCI_SIZE_16);
if (vendor == 0xffff || vendor == 0x0000)
continue;
pci_bus_read_config(bus, bdf, PCI_HEADER_TYPE,
&header_type, PCI_SIZE_8);
if (!PCI_FUNC(bdf))
found_multi = header_type & 0x80;