From 2a87f7fdd599172879633faf33cae7005344d666 Mon Sep 17 00:00:00 2001 From: Hou Zhiqiang <Zhiqiang.Hou@nxp.com> Date: Mon, 8 Oct 2018 16:35:47 +0800 Subject: [PATCH] dm/pci: Change the first CFG read to Vendor ID in enumeration 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> --- drivers/pci/pci-uclass.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/pci/pci-uclass.c b/drivers/pci/pci-uclass.c index 0c52337f33..2cf55cb743 100644 --- a/drivers/pci/pci-uclass.c +++ b/drivers/pci/pci-uclass.c @@ -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; -- 2.39.5