Merge tag 'firewire-fixes-6.7-final' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394

Pull firewire fix from Takashi Sakamoto:
"A single patch to suppress unexpected system reboot in AMD Ryzen
machines with PCIe card consisting of Asmedia ASM1083/1085 and
VT6306/6307/6308.

When the 1394 OHCI driver for the card accesses a specific register
in PCI memory space, the system reboot often occurs.

The issue affects all versions of Linux kernel as long as the 1394
OHCI driver is included. The mechanism of unexpected system reboot is
not clear, so the driver is changed to avoid the access itself when
detecting the combination of hardware"

* tag 'firewire-fixes-6.7-final' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
firewire: ohci: suppress unexpected system reboot in AMD Ryzen machines and ASM108x/VT630x PCIe cards

drivers/firewire/ohci.c

···
 #define QUIRK_TI_SLLZ059		0x20
 #define QUIRK_IR_WAKE			0x40
 
+// On PCI Express Root Complex in any type of AMD Ryzen machine, VIA VT6306/6307/6308 with Asmedia
+// ASM1083/1085 brings an inconvenience that the read accesses to 'Isochronous Cycle Timer' register
+// (at offset 0xf0 in PCI I/O space) often causes unexpected system reboot. The mechanism is not
+// clear, since the read access to the other registers is enough safe; e.g. 'Node ID' register,
+// while it is probable due to detection of any type of PCIe error.
+#define QUIRK_REBOOT_BY_CYCLE_TIMER_READ	0x80000000
+
+#if IS_ENABLED(CONFIG_X86)
+
+static bool has_reboot_by_cycle_timer_read_quirk(const struct fw_ohci *ohci)
+{
+	return !!(ohci->quirks & QUIRK_REBOOT_BY_CYCLE_TIMER_READ);
+}
+
+#define PCI_DEVICE_ID_ASMEDIA_ASM108X	0x1080
+
+static bool detect_vt630x_with_asm1083_on_amd_ryzen_machine(const struct pci_dev *pdev)
+{
+	const struct pci_dev *pcie_to_pci_bridge;
+
+	// Detect any type of AMD Ryzen machine.
+	if (!static_cpu_has(X86_FEATURE_ZEN))
+		return false;
+
+	// Detect VIA VT6306/6307/6308.
+	if (pdev->vendor != PCI_VENDOR_ID_VIA)
+		return false;
+	if (pdev->device != PCI_DEVICE_ID_VIA_VT630X)
+		return false;
+
+	// Detect Asmedia ASM1083/1085.
+	pcie_to_pci_bridge = pdev->bus->self;
+	if (pcie_to_pci_bridge->vendor != PCI_VENDOR_ID_ASMEDIA)
+		return false;
+	if (pcie_to_pci_bridge->device != PCI_DEVICE_ID_ASMEDIA_ASM108X)
+		return false;
+
+	return true;
+}
+
+#else
+#define has_reboot_by_cycle_timer_read_quirk(ohci) false
+#define detect_vt630x_with_asm1083_on_amd_ryzen_machine(pdev)	false
+#endif
+
 /* In case of multiple matches in ohci_quirks[], only the first one is used. */
 static const struct {
 	unsigned short vendor, device, revision, flags;
···
 	u32 t0, t1, t2;
 	s32 diff01, diff12;
 	int i;
+
+	if (has_reboot_by_cycle_timer_read_quirk(ohci))
+		return 0;
 
 	c2 = reg_read(ohci, OHCI1394_IsochronousCycleTimer);
 
···
 		}
 	if (param_quirks)
 		ohci->quirks = param_quirks;
+
+	if (detect_vt630x_with_asm1083_on_amd_ryzen_machine(dev))
+		ohci->quirks |= QUIRK_REBOOT_BY_CYCLE_TIMER_READ;
 
 	/*
 	 * Because dma_alloc_coherent() allocates at least one page,