On Sun, Aug 02, 2020 at 07:28:00PM +0200, Saheed Bolarinwa wrote: > Because the value ~0 has a meaning to some drivers and only No, ~0 means that the PCI read failed. For *every* PCI device I know. Here's me reading from 0xf0 offset of my hostbridge: # setpci -s 00:00.0 0xf0.l 01000000 That device doesn't have extended config space, so the last valid byte is 0xff. Let's read beyond that: # setpci -s 00:00.0 0x100.l ffffffff > Again, only the drivers can determine if ~0 is a valid value. This > information is not available inside pci_config_read*(). Of course it is. *every* change you've done in 6/17 - this is the only patch I have received - checks for == ~0. So that check can just as well be moved inside pci_config_read_*(). Here's how one could do it: #define PCI_OP_READ(size, type, len) \ int noinline pci_bus_read_config_##size \ (struct pci_bus *bus, unsigned int devfn, int pos, type *value) \ { \ int res; \ unsigned long flags; \ u32 data = 0; \ if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER; \ pci_lock_config(flags); \ res = bus->ops->read(bus, devfn, pos, len, &data); \ /* Check we actually read something which is not all 1s.*/ if (data == ~0) return PCIBIOS_READ_FAILED; *value = (type)data; \ pci_unlock_config(flags); \ return res; \ } Also, I'd prefer a function to *not* return void but return either an error or success. In the success case, the @value argument can be consumed by the caller and otherwise not. In any case, that change is a step in the wrong direction and I don't like it, sorry. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel