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authorClemens Ladisch <clemens@ladisch.de>2012-05-24 19:29:19 +0200
committerStefan Richter <stefanr@s5r6.in-berlin.de>2012-05-27 12:31:11 +0200
commit9d60ef2bd87f201c509cfae13ba6c9013446673d (patch)
tree76c4c28d674d33c924f638cde404bfafede88e15 /drivers/firewire
parentf07d42ac7f2a7d650125d0cd7a79631c4522edaf (diff)
downloadlinux-9d60ef2bd87f201c509cfae13ba6c9013446673d.tar.gz
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.c18
1 files changed, 12 insertions, 6 deletions
diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index c1af05e834b..1c365b82781 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;