-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 04/08/11 20:38, Eduardo Horvath wrote: > On Fri, 8 Apr 2011, David Young wrote: > >> Here is a patch that changes the way that the PCI subsystem and >> drivers use PCI_FLAGS_IO_ENABLED and PCI_FLAGS_MEM_ENABLED. I >> went ahead and renamed the flags in order to poison old-fashioned >> uses. Now they're called PCI_FLAGS_IO_OKAY and >> PCI_FLAGS_MEM_OKAY. >> >> For simplicity's sake, I'll just write of PCI_FLAGS_IO_ENABLED, >> below, but the same discussion applies to PCI_FLAGS_MEM_ENABLED. >> >> Traditionally, if PCI_FLAGS_IO_ENABLED is set in the >> pci_attach_args.pa_flags, it tells a PCI device driver, "the >> bridges upstream forward PCI I/O transactions to this device, >> *and* I/O transactions are enabled in the device's PCI CSR." >> Some drivers, finding that neither PCI_FLAGS_IO_ENABLED nor the >> corresponding PCI CSR bit is set set both pa_flags and the CSR >> themselves. Those drivers assume that the upstream bridges are >> forwarding I/O transactions, which may or may not be true. They >> have to assume, though, because the information in pa_flags is >> not specific. >> >> My patch makes the PCI_FLAGS_IO_OKAY condition more specific: it >> tells a PCI device driver, "the bridges upstream forward PCI I/O >> transactions to this device". If the flag isn't set, the driver >> has no business setting it. Also, if the flag isn't set, there's >> not much use in the driver setting the corresponding bit in the >> PCI CSR. > > It looks like you're renaming constants. What is the functional > change here other than renaming things? What happens to drivers > that use the old *IO_ENABLED flags? What are you trying to > accomplish here? > > Eduardo > If I got it right the functional change is that a device drivers do not enable mem or io upstream the bus. For me this seems right, it makes responsibilities right, the only corner case I can think off (after short time thinking) is are there any device drivers that are known to do this in order to work.
Lars - -- - ------------------------------------ Mystische Erklärungen: Die mystischen Erklärungen gelten für tief; die Wahrheit ist, dass sie noch nicht einmal oberflächlich sind. -- Friedrich Nietzsche [ Die Fröhliche Wissenschaft Buch 3, 126 ] -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.17 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk2fV0kACgkQcxuYqjT7GRZCnQCgrR6E7RGvbuDpz0JRqZUgfdyf NxkAoMzNDf6uuuKmxc7m+0sD7KPFPtJR =pBDm -----END PGP SIGNATURE-----
