i386: Fix Cyrix MediaGX detection From: Alan The old Cyrix 5520 CPU detection code relied upon the PCI layer setup being done earlier than the CPU setup, which is no longer true. Fortunately we know that if the processor is a MediaGX we can do type 1 pci config accesses to check the companion chip. We thus do those directly and from this find the 5520 and implement the workarounds for the timer problem Original report from takada@mbf.nifty.com, I sent a proposed patch which Takara then corrected, tested and sent back to the list on 10th January. Submitting for merging as it seems to have been missed AK: Changed to use pci-direct.h and fix warning for !CONFIG_PCI (later AK: originally from akpm) Signed-off-by: Alan Cox Signed-off-by: Andi Kleen Cc: Andi Kleen Cc: Cc: Jordan Crouse Signed-off-by: Andrew Morton --- arch/i386/kernel/cpu/cyrix.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) Index: linux/arch/i386/kernel/cpu/cyrix.c =================================================================== --- linux.orig/arch/i386/kernel/cpu/cyrix.c +++ linux/arch/i386/kernel/cpu/cyrix.c @@ -6,6 +6,7 @@ #include #include #include +#include #include "cpu.h" @@ -183,14 +184,6 @@ static void __cpuinit geode_configure(vo } -#ifdef CONFIG_PCI -static struct pci_device_id __cpuinitdata cyrix_55x0[] = { - { PCI_DEVICE(PCI_VENDOR_ID_CYRIX, PCI_DEVICE_ID_CYRIX_5510) }, - { PCI_DEVICE(PCI_VENDOR_ID_CYRIX, PCI_DEVICE_ID_CYRIX_5520) }, - { }, -}; -#endif - static void __cpuinit init_cyrix(struct cpuinfo_x86 *c) { unsigned char dir0, dir0_msn, dir0_lsn, dir1 = 0; @@ -258,6 +251,8 @@ static void __cpuinit init_cyrix(struct case 4: /* MediaGX/GXm or Geode GXM/GXLV/GX1 */ #ifdef CONFIG_PCI + { + u32 vendor, device; /* It isn't really a PCI quirk directly, but the cure is the same. The MediaGX has deep magic SMM stuff that handles the SB emulation. It thows away the fifo on disable_dma() which @@ -273,12 +268,19 @@ static void __cpuinit init_cyrix(struct printk(KERN_INFO "Working around Cyrix MediaGX virtual DMA bugs.\n"); isa_dma_bridge_buggy = 2; + /* We do this before the PCI layer is running. However we + are safe here as we know the bridge must be a Cyrix + companion and must be present */ + vendor = read_pci_config_16(0, 0, 0x12, PCI_VENDOR_ID); + device = read_pci_config_16(0, 0, 0x12, PCI_DEVICE_ID); /* * The 5510/5520 companion chips have a funky PIT. */ - if (pci_dev_present(cyrix_55x0)) + if (vendor == PCI_VENDOR_ID_CYRIX && + (device == PCI_DEVICE_ID_CYRIX_5510 || device == PCI_DEVICE_ID_CYRIX_5520)) pit_latch_buggy = 1; + } #endif c->x86_cache_size=16; /* Yep 16K integrated cache thats it */