This patch adds a comment to the header with the PCI_foo macros related to DEVFN to explain the difference in U-Boot vs Linux.

Signed-off-by: Stefan Roese sr@denx.de Cc: Simon Glass sjg@chromium.org Cc: Bin Meng bmeng.cn@gmail.com --- include/pci.h | 11 +++++++++++ 1 file changed, 11 insertions(+)

diff --git a/include/pci.h b/include/pci.h index 041f8e3747..93fdd8fe6a 100644 --- a/include/pci.h +++ b/include/pci.h @@ -499,9 +499,20 @@ static inline void pci_set_region(struct pci_region *reg, typedef int pci_dev_t;

#define PCI_BUS(d) (((d) >> 16) & 0xff) + +/* + * Please note the difference in DEVFN usage in U-Boot vs Linux. U-Boot + * uses DEVFN in bits 15-8 but Linux instead expects DEVFN in bits 7-0. + * Please see the Linux header include/uapi/linux/pci.h for more details. + * This is relevant for the following macros: + * PCI_DEV, PCI_FUNC, PCI_DEVFN + * The U-Boot macro PCI_DEV is equivalent to the Linux PCI_SLOT version with + * the remark from above (input d in bits 15-8 instead of 7-0. + */ #define PCI_DEV(d) (((d) >> 11) & 0x1f) #define PCI_FUNC(d) (((d) >> 8) & 0x7) #define PCI_DEVFN(d, f) ((d) << 11 | (f) << 8) + #define PCI_MASK_BUS(bdf) ((bdf) & 0xffff) #define PCI_ADD_BUS(bus, devfn) (((bus) << 16) | (devfn)) #define PCI_BDF(b, d, f) ((b) << 16 | PCI_DEVFN(d, f))