From: Ondrej Zajicek <santiago@xxxxxxxxxxxxx> Date: Mon, 5 Aug 2013 22:29:55 +0200 > On Sun, Aug 04, 2013 at 06:51:46PM -0700, David Miller wrote: >> From: "H. Peter Anvin" <hpa@xxxxxxxxx> >> Date: Sun, 04 Aug 2013 10:33:46 -0700 >> >> > Anyone who can dig backwards and summarize? In other words: >> > >> > Where in the current code do we stuff a physical address in a pointer, >> > or a virtual address into a non-pointer? >> >> The VGA register accessors try to accomodate iomem and ioport >> accesses. >> >> If they are given a non-NULL iomem pointer 'regbase' they use >> iomem accesses, otherwise they do direct ISA port poking. >> >> And yes the drivers in question are making some brash assumptions. >> I suspect they should be using ioremap() or similar. > > Well, these drivers were written without MMIO (port IO only with NULL > instead of 'vgabase' for VGA register accessors). They were converted in > patches 94c322c30bd14ae6cdd369cb4a1f94c5c3809ac9, > f8645933513c65ac55f23c63b2649097289795c6 and a few others (from David > Miller) to potentially use MMIO by using 'vgabase' instead of NULL: > > pcibios_bus_to_resource(dev, &vga_res, &bus_reg); > par->state.vgabase = (void __iomem *) vga_res.start; > > How this could even work? AFAIK these cards have to be explicitly programmed > to enable MMIO (which was not done in the patches). These patches claim that > it is for multi-domain PCI. I would guess that vgabase is NULL in common > configurations but if it is non-NULL, it probably wouldn't work, unless > there is some hardware magic that transparently converts MMIO (from CPU PoV) > to port IO (from card/PCI PoV). > > Note that there are some later patches (86c0f043a737dadf034a4e6f29aefb074f4a1146) > from Ondrej Zary that independently enable MMIO, but they use par->mmio > field instead of par->state.vgabase . Ok, so the correct fix would be to make them pass NULL again and to simply ignore the resources. -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
