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authorAlan Stern <stern@rowland.harvard.edu>2013-03-18 12:04:54 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-03-18 16:05:58 -0700
commit6d5df8976266d8e40603601f7695537f9f3dc9e2 (patch)
tree7870d6ddb4ca6a5cee7d5e2923ddecd0b3c7305a /drivers/usb/host/ehci-timer.c
parent413fd1e9aa3e0441e64ed4703ce1bba164e135c0 (diff)
downloadlinux-stericsson-6d5df8976266d8e40603601f7695537f9f3dc9e2.tar.gz
USB: EHCI: decrease schedule-status poll timeout
This patch (as1657) decreases the timeout used by ehci-hcd for polling the async and periodic schedule statuses. The timeout is currently set to 20 ms, which is much too high. Controllers should always update the schedule status within one or two ms of being told to do so; if they don't then something is wrong. Furthermore, bug reports have shown that sometimes controllers (particularly those made by VIA) don't update the status bit at all, even when the schedule does change state. When this happens, polling for 20 ms would cause an unnecessarily long delay. The delay is reduced to somewhere between 2 and 4 ms, depending on the slop allowed by the kernel's high-res timers. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/host/ehci-timer.c')
-rw-r--r--drivers/usb/host/ehci-timer.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/usb/host/ehci-timer.c b/drivers/usb/host/ehci-timer.c
index 20dbdcbe9b0f..cc9ad5892d19 100644
--- a/drivers/usb/host/ehci-timer.c
+++ b/drivers/usb/host/ehci-timer.c
@@ -113,8 +113,8 @@ static void ehci_poll_ASS(struct ehci_hcd *ehci)
if (want != actual) {
- /* Poll again later, but give up after about 20 ms */
- if (ehci->ASS_poll_count++ < 20) {
+ /* Poll again later, but give up after about 2-4 ms */
+ if (ehci->ASS_poll_count++ < 2) {
ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true);
return;
}
@@ -159,8 +159,8 @@ static void ehci_poll_PSS(struct ehci_hcd *ehci)
if (want != actual) {
- /* Poll again later, but give up after about 20 ms */
- if (ehci->PSS_poll_count++ < 20) {
+ /* Poll again later, but give up after about 2-4 ms */
+ if (ehci->PSS_poll_count++ < 2) {
ehci_enable_event(ehci, EHCI_HRTIMER_POLL_PSS, true);
return;
}