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ioat: switch watchdog and reset handler from workqueue to timer

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In order to support dynamic resizing of the descriptor ring or polling
for a descriptor in the presence of a hung channel the reset handler
needs to make progress while in a non-preemptible context.  The current
workqueue implementation precludes polling channel reset completion
under spin_lock().

This conversion also allows us to return to opportunistic cleanup in the
ioat2 case as the timer implementation guarantees at least one cleanup
after every descriptor is submitted.  This means the worst case
completion latency becomes the timer frequency (for exceptional
circumstances), but with the benefit of avoiding busy waiting when the
lock is contended.

Signed-off-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams
2009-09-08 12:01:49 -07:00
parent ad643f54c8
commit 09c8a5b85e
6 changed files with 397 additions and 437 deletions
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16
drivers/idle/i7300_idle.c
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@@ -126,9 +126,9 @@ static void i7300_idle_ioat_stop(void)
udelay(10);
sts = readq(ioat_chanbase + IOAT1_CHANSTS_OFFSET) &
IOAT_CHANSTS_DMA_TRANSFER_STATUS;
IOAT_CHANSTS_STATUS;
if (sts != IOAT_CHANSTS_DMA_TRANSFER_STATUS_ACTIVE)
if (sts != IOAT_CHANSTS_ACTIVE)
break;
}
@@ -160,9 +160,9 @@ static int __init i7300_idle_ioat_selftest(u8 *ctl,
udelay(1000);
chan_sts = readq(ioat_chanbase + IOAT1_CHANSTS_OFFSET) &
IOAT_CHANSTS_DMA_TRANSFER_STATUS;
IOAT_CHANSTS_STATUS;
if (chan_sts != IOAT_CHANSTS_DMA_TRANSFER_STATUS_DONE) {
if (chan_sts != IOAT_CHANSTS_DONE) {
/* Not complete, reset the channel */
writeb(IOAT_CHANCMD_RESET,
ioat_chanbase + IOAT1_CHANCMD_OFFSET);
@@ -288,9 +288,9 @@ static void __exit i7300_idle_ioat_exit(void)
ioat_chanbase + IOAT1_CHANCMD_OFFSET);
chan_sts = readq(ioat_chanbase + IOAT1_CHANSTS_OFFSET) &
IOAT_CHANSTS_DMA_TRANSFER_STATUS;
IOAT_CHANSTS_STATUS;
if (chan_sts != IOAT_CHANSTS_DMA_TRANSFER_STATUS_ACTIVE) {
if (chan_sts != IOAT_CHANSTS_ACTIVE) {
writew(0, ioat_chanbase + IOAT_CHANCTRL_OFFSET);
break;
}
@@ -298,14 +298,14 @@ static void __exit i7300_idle_ioat_exit(void)
}
chan_sts = readq(ioat_chanbase + IOAT1_CHANSTS_OFFSET) &
IOAT_CHANSTS_DMA_TRANSFER_STATUS;
IOAT_CHANSTS_STATUS;
/*
* We tried to reset multiple times. If IO A/T channel is still active
* flag an error and return without cleanup. Memory leak is better
* than random corruption in that extreme error situation.
*/
if (chan_sts == IOAT_CHANSTS_DMA_TRANSFER_STATUS_ACTIVE) {
if (chan_sts == IOAT_CHANSTS_ACTIVE) {
printk(KERN_ERR I7300_PRINT "Unable to stop IO A/T channels."
" Not freeing resources\n");
return;