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-rw-r--r--drivers/firewire/ohci.c52
1 files changed, 49 insertions, 3 deletions
diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 6610d2d38802..d6ba897b2197 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -192,6 +192,7 @@ struct fw_ohci {
bool use_dualbuffer;
bool old_uninorth;
bool bus_reset_packet_quirk;
+ bool iso_cycle_timer_quirk;
/*
* Spinlock for accessing fw_ohci data. Never call out of
@@ -1794,14 +1795,57 @@ static int ohci_enable_phys_dma(struct fw_card *card,
#endif /* CONFIG_FIREWIRE_OHCI_REMOTE_DMA */
}
+static inline u32 cycle_timer_ticks(u32 cycle_timer)
+{
+ u32 ticks;
+
+ ticks = cycle_timer & 0xfff;
+ ticks += 3072 * ((cycle_timer >> 12) & 0x1fff);
+ ticks += (3072 * 8000) * (cycle_timer >> 25);
+ return ticks;
+}
+
static u64 ohci_get_bus_time(struct fw_card *card)
{
struct fw_ohci *ohci = fw_ohci(card);
- u32 cycle_time;
+ u32 c0, c1, c2;
+ u32 t0, t1, t2;
+ s32 diff01, diff12;
u64 bus_time;
- cycle_time = reg_read(ohci, OHCI1394_IsochronousCycleTimer);
- bus_time = ((u64)atomic_read(&ohci->bus_seconds) << 32) | cycle_time;
+ if (!ohci->iso_cycle_timer_quirk) {
+ c2 = reg_read(ohci, OHCI1394_IsochronousCycleTimer);
+ } else {
+ /*
+ * VIA controllers have two bugs when updating the iso cycle
+ * timer register:
+ * 1) When the lowest six bits are wrapping around to zero,
+ * a read that happens at the same time will return garbage
+ * in the lowest ten bits.
+ * 2) When the cycleOffset field wraps around to zero, the
+ * cycleCount field is not incremented for about 60 ns.
+ *
+ * To catch these, we read the register three times and ensure
+ * that the difference between each two consecutive reads is
+ * approximately the same, i.e., less than twice the other.
+ * Furthermore, any negative difference indicates an error.
+ * (A PCI read should take at least 20 ticks of the 24.576 MHz
+ * timer to execute, so we have enough precision to compute the
+ * ratio of the differences.)
+ */
+ do {
+ c0 = reg_read(ohci, OHCI1394_IsochronousCycleTimer);
+ c1 = reg_read(ohci, OHCI1394_IsochronousCycleTimer);
+ c2 = reg_read(ohci, OHCI1394_IsochronousCycleTimer);
+ t0 = cycle_timer_ticks(c0);
+ t1 = cycle_timer_ticks(c1);
+ t2 = cycle_timer_ticks(c2);
+ diff01 = t1 - t0;
+ diff12 = t2 - t1;
+ } while (diff01 <= 0 || diff12 <= 0 ||
+ diff01 / diff12 >= 2 || diff12 / diff01 >= 2);
+ }
+ bus_time = ((u64)atomic_read(&ohci->bus_seconds) << 32) | c2;
return bus_time;
}
@@ -2498,6 +2542,8 @@ static int __devinit pci_probe(struct pci_dev *dev,
#endif
ohci->bus_reset_packet_quirk = dev->vendor == PCI_VENDOR_ID_TI;
+ ohci->iso_cycle_timer_quirk = dev->vendor == PCI_VENDOR_ID_VIA;
+
ar_context_init(&ohci->ar_request_ctx, ohci,
OHCI1394_AsReqRcvContextControlSet);
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