From ba380013b681e91e059f95b51002f8d43024b371 Mon Sep 17 00:00:00 2001 From: Michael Buesch Date: Tue, 15 Apr 2008 21:13:36 +0200 Subject: [PATCH] b43: Add fastpath to b43_mac_suspend() This adds a fastpath for the common workloads to the MAC suspend flushing. In common workloads the FIFO flush will take between 100 and 200 microseconds. So we want to avoid calling msleep() in the common case, as it will waste over 800 microseconds + scheduler overhead. This fastpath will hit in workloads where only small chunks of data are transmitted (downloading a file) or when a TX rate bigger or equal to 24MBit/s is used when transmitting lots of stuff (iperf). So in the commonly used workloads it will basically always hit. In case the fastpath is not hit, there's no real performance or latency disadvantage from that. And yes, I measured this. So this is not one of these bad Programmer Likeliness Assumptions that are always wrong. ;) Signed-off-by: Michael Buesch Signed-off-by: John W. Linville --- drivers/net/wireless/b43/main.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/net/wireless/b43/main.c b/drivers/net/wireless/b43/main.c index 345c34bdae9a..cf5c046c9fa8 100644 --- a/drivers/net/wireless/b43/main.c +++ b/drivers/net/wireless/b43/main.c @@ -2343,6 +2343,13 @@ static void b43_mac_suspend(struct b43_wldev *dev) & ~B43_MACCTL_ENABLED); /* force pci to flush the write */ b43_read32(dev, B43_MMIO_MACCTL); + for (i = 35; i; i--) { + tmp = b43_read32(dev, B43_MMIO_GEN_IRQ_REASON); + if (tmp & B43_IRQ_MAC_SUSPENDED) + goto out; + udelay(10); + } + /* Hm, it seems this will take some time. Use msleep(). */ for (i = 40; i; i--) { tmp = b43_read32(dev, B43_MMIO_GEN_IRQ_REASON); if (tmp & B43_IRQ_MAC_SUSPENDED)