[PATCH] IB/ipath: fix lost interrupts on HT-400
Do an extra check to see if in-memory tail changed while processing packets, and if so, going back through the loop again (but only once per call to ipath_kreceive()). In practice, this seems to be enough to guarantee that if we crossed the clearing of an interrupt at start of ipath_intr with a scheduled tail register update, that we'll process the "extra" packet that lost the interrupt because we cleared it just as it was about to arrive. Signed-off-by: Dave Olson <dave.olson@qlogic.com> Signed-off-by: Bryan O'Sullivan <bryan.osullivan@qlogic.com> Cc: "Michael S. Tsirkin" <mst@mellanox.co.il> Cc: Roland Dreier <rolandd@cisco.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -870,7 +870,7 @@ void ipath_kreceive(struct ipath_devdata *dd)
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const u32 maxcnt = dd->ipath_rcvhdrcnt * rsize; /* words */
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u32 etail = -1, l, hdrqtail;
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struct ips_message_header *hdr;
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u32 eflags, i, etype, tlen, pkttot = 0, updegr=0;
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u32 eflags, i, etype, tlen, pkttot = 0, updegr=0, reloop=0;
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static u64 totcalls; /* stats, may eventually remove */
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char emsg[128];
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@ -885,9 +885,11 @@ void ipath_kreceive(struct ipath_devdata *dd)
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goto bail;
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l = dd->ipath_port0head;
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if (l == (u32)le64_to_cpu(*dd->ipath_hdrqtailptr))
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hdrqtail = (u32) le64_to_cpu(*dd->ipath_hdrqtailptr);
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if (l == hdrqtail)
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goto done;
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reloop:
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/* read only once at start for performance */
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hdrqtail = (u32)le64_to_cpu(*dd->ipath_hdrqtailptr);
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@ -1011,7 +1013,7 @@ void ipath_kreceive(struct ipath_devdata *dd)
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*/
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if (l == hdrqtail || (i && !(i&0xf))) {
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u64 lval;
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if (l == hdrqtail) /* want interrupt only on last */
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if (l == hdrqtail) /* PE-800 interrupt only on last */
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lval = dd->ipath_rhdrhead_intr_off | l;
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else
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lval = l;
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@ -1024,6 +1026,23 @@ void ipath_kreceive(struct ipath_devdata *dd)
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}
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}
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if (!dd->ipath_rhdrhead_intr_off && !reloop) {
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/* HT-400 workaround; we can have a race clearing chip
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* interrupt with another interrupt about to be delivered,
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* and can clear it before it is delivered on the GPIO
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* workaround. By doing the extra check here for the
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* in-memory tail register updating while we were doing
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* earlier packets, we "almost" guarantee we have covered
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* that case.
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*/
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u32 hqtail = (u32)le64_to_cpu(*dd->ipath_hdrqtailptr);
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if (hqtail != hdrqtail) {
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hdrqtail = hqtail;
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reloop = 1; /* loop 1 extra time at most */
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goto reloop;
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}
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}
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pkttot += i;
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dd->ipath_port0head = l;
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@ -766,7 +766,7 @@ irqreturn_t ipath_intr(int irq, void *data, struct pt_regs *regs)
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u32 istat, chk0rcv = 0;
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ipath_err_t estat = 0;
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irqreturn_t ret;
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u32 p0bits, oldhead;
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u32 oldhead, curtail;
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static unsigned unexpected = 0;
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static const u32 port0rbits = (1U<<INFINIPATH_I_RCVAVAIL_SHIFT) |
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(1U<<INFINIPATH_I_RCVURG_SHIFT);
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@ -809,15 +809,16 @@ irqreturn_t ipath_intr(int irq, void *data, struct pt_regs *regs)
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* lose intr for later packets that arrive while we are processing.
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*/
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oldhead = dd->ipath_port0head;
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if (oldhead != (u32) le64_to_cpu(*dd->ipath_hdrqtailptr)) {
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curtail = (u32)le64_to_cpu(*dd->ipath_hdrqtailptr);
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if (oldhead != curtail) {
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if (dd->ipath_flags & IPATH_GPIO_INTR) {
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ipath_write_kreg(dd, dd->ipath_kregs->kr_gpio_clear,
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(u64) (1 << 2));
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p0bits = port0rbits | INFINIPATH_I_GPIO;
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istat = port0rbits | INFINIPATH_I_GPIO;
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}
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else
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p0bits = port0rbits;
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ipath_write_kreg(dd, dd->ipath_kregs->kr_intclear, p0bits);
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istat = port0rbits;
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ipath_write_kreg(dd, dd->ipath_kregs->kr_intclear, istat);
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ipath_kreceive(dd);
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if (oldhead != dd->ipath_port0head) {
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ipath_stats.sps_fastrcvint++;
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@ -827,7 +828,6 @@ irqreturn_t ipath_intr(int irq, void *data, struct pt_regs *regs)
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}
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istat = ipath_read_kreg32(dd, dd->ipath_kregs->kr_intstatus);
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p0bits = port0rbits;
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if (unlikely(!istat)) {
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ipath_stats.sps_nullintr++;
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@ -891,18 +891,18 @@ irqreturn_t ipath_intr(int irq, void *data, struct pt_regs *regs)
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/* Clear GPIO status bit 2 */
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ipath_write_kreg(dd, dd->ipath_kregs->kr_gpio_clear,
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(u64) (1 << 2));
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p0bits |= INFINIPATH_I_GPIO;
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chk0rcv = 1;
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}
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}
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chk0rcv |= istat & p0bits;
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chk0rcv |= istat & port0rbits;
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/*
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* clear the ones we will deal with on this round
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* We clear it early, mostly for receive interrupts, so we
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* know the chip will have seen this by the time we process
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* the queue, and will re-interrupt if necessary. The processor
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* itself won't take the interrupt again until we return.
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* Clear the interrupt bits we found set, unless they are receive
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* related, in which case we already cleared them above, and don't
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* want to clear them again, because we might lose an interrupt.
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* Clear it early, so we "know" know the chip will have seen this by
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* the time we process the queue, and will re-interrupt if necessary.
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* The processor itself won't take the interrupt again until we return.
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*/
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ipath_write_kreg(dd, dd->ipath_kregs->kr_intclear, istat);
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