01_i386_and_x86_64_implement-dma_broken_dac.patch
CK804 PCI bridge fails to forward DAC commands from the
secondary bus to the primary, which is required by PCI
specification from ver1.1. This patch implements
dma_broken_dac() which tests whether there is any such bridge
among parents of a given device.
Signed-off-by: Tejun Heo <[email protected]>
quirks.c | 39 +++++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)
Index: linux-work/arch/i386/kernel/quirks.c
===================================================================
--- linux-work.orig/arch/i386/kernel/quirks.c 2005-09-28 21:41:46.000000000 +0900
+++ linux-work/arch/i386/kernel/quirks.c 2005-09-28 21:41:46.000000000 +0900
@@ -5,6 +5,45 @@
#include <linux/pci.h>
#include <linux/irq.h>
+/*
+ * The following function is called from dma_supported and needed by
+ * both i386 and x86_64.
+ *
+ * Some bridges fail to forward DAC commands upwards even though it's
+ * required by PCI specification (from 1.1).
+ */
+static struct pci_device_id bridges_with_broken_dac[] = {
+ /* nVidia CK804 PCI Bridge */
+ { PCI_VENDOR_ID_NVIDIA, 0x005c, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0 },
+ { }
+};
+
+int __devinit dma_broken_dac(struct device *dev)
+{
+ struct device *bridge;
+
+ /*
+ * Disable DAC if any parent bridge has broken DAC support on
+ * the assumption that memory is located above host bridge.
+ */
+ bridge = dev->parent;
+ while (bridge && bridge->bus == &pci_bus_type) {
+ const struct pci_device_id *id;
+ id = pci_match_id(bridges_with_broken_dac, to_pci_dev(bridge));
+ if (id) {
+ printk(KERN_WARNING "PCI %s: bridge %s has broken DAC support, 64bit DMA disabled\n",
+ dev->bus_id, bridge->bus_id);
+ return 1;
+ }
+ bridge = bridge->parent;
+ }
+
+ return 0;
+}
+
+/*
+ * PCI fixups start here
+ */
#if defined(CONFIG_X86_IO_APIC) && defined(CONFIG_SMP) && defined(CONFIG_PCI)
static void __devinit quirk_intel_irqbalance(struct pci_dev *dev)
-
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