This patch makes 2.1.113 compile without CONFIG_PCI_DIRECT and also makes
the direct hardware access more paranoid than before (for more information,
just see the comment).
Have a nice fortnight
-- Martin `MJ' Mares <mj@ucw.cz> http://atrey.karlin.mff.cuni.cz/~mj/ Faculty of Math and Physics, Charles University, Prague, Czech Rep., Earth "Immanuel doesn't pun, he Kant."
--- /mj/linux-2.1/arch/i386/kernel/bios32.c Tue Aug 4 15:19:37 1998 +++ arch/i386/kernel/bios32.c Tue Aug 4 18:54:11 1998 @@ -1,7 +1,7 @@ /* * bios32.c - Low-Level PCI Access * - * $Id: bios32.c,v 1.43 1998/08/03 15:59:20 mj Exp $ + * $Id: bios32.c,v 1.44 1998/08/04 14:54:56 mj Exp $ * * Copyright 1993, 1994 Drew Eckhardt * Visionary Computing @@ -65,6 +65,12 @@ * * Jun 19, 1998 : Changed to use spinlocks, so that PCI configuration space * can be accessed from interrupts even on SMP systems. [mj] + * + * August 1998 : Better support for peer host bridges and more paranoid + * checks for direct hardware access. Ugh, this file starts to look as + * a large gallery of common hardware bug workarounds (watch the comments) + * -- the PCI specs themselves are sane, but most implementors should be + * hit hard with \hammer scaled \magstep5. [mj] */ #include <linux/config.h> @@ -331,6 +337,25 @@ pci_conf2_write_config_dword }; +/* + * Before we decide to use direct hardware access mechanisms, we try to do some + * trivial checks to ensure it at least _seems_ to be working -- we just test + * whether bus 00 contains a host bridge (this is similar to checking + * techniques used in XFree86, but ours should be more reliable since we + * attempt to make use of direct access hints provided by the PCI BIOS). + */ +__initfunc(int pci_sanity_check(struct pci_access *a)) +{ + u16 dfn, class; + + for(dfn=0; dfn < 0x100; dfn++) + if (!a->read_config_word(0, dfn, PCI_CLASS_DEVICE, &class) && + class == PCI_CLASS_BRIDGE_HOST) + return 1; + DBG("PCI: Sanity check failed\n"); + return 0; +} + __initfunc(static struct pci_access *pci_check_direct(void)) { unsigned int tmp; @@ -345,7 +370,8 @@ outb (0x01, 0xCFB); tmp = inl (0xCF8); outl (0x80000000, 0xCF8); - if (inl (0xCF8) == 0x80000000) { + if (inl (0xCF8) == 0x80000000 && + pci_sanity_check(&pci_direct_conf1)) { outl (tmp, 0xCF8); __restore_flags(flags); printk("PCI: Using configuration type 1\n"); @@ -361,7 +387,8 @@ outb (0x00, 0xCFB); outb (0x00, 0xCF8); outb (0x00, 0xCFA); - if (inb (0xCF8) == 0x00 && inb (0xCFA) == 0x00) { + if (inb (0xCF8) == 0x00 && inb (0xCFA) == 0x00 && + pci_sanity_check(&pci_direct_conf2)) { __restore_flags(flags); printk("PCI: Using configuration type 2\n"); return &pci_direct_conf2; @@ -920,6 +947,7 @@ struct pci_bus *b = &pci_root; int i; +#ifdef CONFIG_PCI_DIRECT /* * Don't search for peer host bridges if we use config type 2 * since it reads bogus values for non-existent busses and @@ -927,6 +955,7 @@ */ if (access_pci == &pci_direct_conf2) return; +#endif do { int n = b->subordinate+1; u16 l;
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