diff options
| author | Clemens Ladisch <clemens@ladisch.de> | 2012-05-24 19:29:19 +0200 |
|---|---|---|
| committer | Stefan Richter <stefanr@s5r6.in-berlin.de> | 2012-05-27 12:31:11 +0200 |
| commit | 9d60ef2bd87f201c509cfae13ba6c9013446673d (patch) | |
| tree | 76c4c28d674d33c924f638cde404bfafede88e15 /drivers/firewire | |
| parent | firewire: core: allocate the low memory region (diff) | |
| download | linux-9d60ef2bd87f201c509cfae13ba6c9013446673d.tar.xz linux-9d60ef2bd87f201c509cfae13ba6c9013446673d.zip | |
firewire: ohci: lazy bus time initialization
The Bus_Time CSR is virtually never used, so we can avoid burning CPU in
interrupt context for 1 or 3 IsochronousCycleTimer accesses every minute
by not tracking the bus time until the CSR is actually accessed for the
first time.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Diffstat (limited to 'drivers/firewire')
| -rw-r--r-- | drivers/firewire/ohci.c | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c index c1af05e834b6..1c365b827815 100644 --- a/drivers/firewire/ohci.c +++ b/drivers/firewire/ohci.c @@ -191,6 +191,7 @@ struct fw_ohci { unsigned quirks; unsigned int pri_req_max; u32 bus_time; + bool bus_time_running; bool is_root; bool csr_state_setclear_abdicate; int n_ir; @@ -1726,6 +1727,13 @@ static u32 update_bus_time(struct fw_ohci *ohci) { u32 cycle_time_seconds = get_cycle_time(ohci) >> 25; + if (unlikely(!ohci->bus_time_running)) { + reg_write(ohci, OHCI1394_IntMaskSet, OHCI1394_cycle64Seconds); + ohci->bus_time = (lower_32_bits(get_seconds()) & ~0x7f) | + (cycle_time_seconds & 0x40); + ohci->bus_time_running = true; + } + if ((ohci->bus_time & 0x40) != (cycle_time_seconds & 0x40)) ohci->bus_time += 0x40; @@ -2213,7 +2221,7 @@ static int ohci_enable(struct fw_card *card, { struct fw_ohci *ohci = fw_ohci(card); struct pci_dev *dev = to_pci_dev(card->device); - u32 lps, seconds, version, irqs; + u32 lps, version, irqs; int i, ret; if (software_reset(ohci)) { @@ -2269,9 +2277,7 @@ static int ohci_enable(struct fw_card *card, (OHCI1394_MAX_PHYS_RESP_RETRIES << 8) | (200 << 16)); - seconds = lower_32_bits(get_seconds()); - reg_write(ohci, OHCI1394_IsochronousCycleTimer, seconds << 25); - ohci->bus_time = seconds & ~0x3f; + ohci->bus_time_running = false; version = reg_read(ohci, OHCI1394_Version) & 0x00ff00ff; if (version >= OHCI_VERSION_1_1) { @@ -2369,7 +2375,6 @@ static int ohci_enable(struct fw_card *card, OHCI1394_postedWriteErr | OHCI1394_selfIDComplete | OHCI1394_regAccessFail | - OHCI1394_cycle64Seconds | OHCI1394_cycleInconsistent | OHCI1394_unrecoverableError | OHCI1394_cycleTooLong | @@ -2658,7 +2663,8 @@ static void ohci_write_csr(struct fw_card *card, int csr_offset, u32 value) case CSR_BUS_TIME: spin_lock_irqsave(&ohci->lock, flags); - ohci->bus_time = (ohci->bus_time & 0x7f) | (value & ~0x7f); + ohci->bus_time = (update_bus_time(ohci) & 0x40) | + (value & ~0x7f); spin_unlock_irqrestore(&ohci->lock, flags); break; |