[PATCH REPOST] IB/ehca: In case of lost interrupts, trigger EOI to reenable interrupts

During corner case testing, we noticed that some versions of ehca 
do not properly transition to interrupt done in special load situations.
This can be resolved by periodically triggering EOI through H_EOI, 
if eqes are pending.

Signed-off-by: Stefan Roscher <redacted>

---
This patch replaces my previous patch-set.
As Paul suggested, this version of the patch calls H_EOI directly and doesn't need
any ibmebus changes.
 
 drivers/infiniband/hw/ehca/ehca_main.c |   11 +++++++++--
 drivers/infiniband/hw/ehca/hcp_if.c    |   11 +++++++++++
 drivers/infiniband/hw/ehca/hcp_if.h    |    1 +
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/hw/ehca/ehca_main.c b/drivers/infiniband/hw/ehca/ehca_main.c
index 482103e..add4ff4 100644
--- a/drivers/infiniband/hw/ehca/ehca_main.c
+++ b/drivers/infiniband/hw/ehca/ehca_main.c

@@ -937,6 +937,7 @@ static struct of_platform_driver ehca_driver = {
 void ehca_poll_eqs(unsigned long data)
 {
 	struct ehca_shca *shca;
+	u64 ret;
 
 	spin_lock(&shca_list_lock);
 	list_for_each_entry(shca, &shca_list, shca_list) {

@@ -955,8 +956,14 @@ void ehca_poll_eqs(unsigned long data)
 				spin_unlock_irqrestore(&eq->spinlock, flags);
 				max--;
 			} while (q_ofs == q_ofs2 && max > 0);
-			if (q_ofs == q_ofs2)
-				ehca_process_eq(shca, 0);
+			if (q_ofs == q_ofs2) {
+				ret = hipz_h_eoi(eq->ist);
+				if (ret != H_SUCCESS)
+					ehca_err(&shca->ib_device,
+						 "bad return code EOI -"
+						 "rc = %ld\n", ret);
+				tasklet_hi_schedule(&shca->eq.interrupt_task);
+			}
 		}
 	}
 	mod_timer(&poll_eqs_timer, round_jiffies(jiffies + HZ));

diff --git a/drivers/infiniband/hw/ehca/hcp_if.c b/drivers/infiniband/hw/ehca/hcp_if.c
index 5245e13..7084efd 100644
--- a/drivers/infiniband/hw/ehca/hcp_if.c
+++ b/drivers/infiniband/hw/ehca/hcp_if.c

@@ -933,3 +933,14 @@ u64 hipz_h_error_data(const struct ipz_adapter_handle adapter_handle,
 				       r_cb,
 				       0, 0, 0, 0);
 }
+
+u64 hipz_h_eoi(int irq)
+{
+	int value;
+	unsigned long xirr;
+
+	iosync();
+	value = (0xff << 24) | irq;
+	xirr = value & 0xffffffff;
+	return plpar_hcall_norets(H_EOI, xirr);
+}

diff --git a/drivers/infiniband/hw/ehca/hcp_if.h b/drivers/infiniband/hw/ehca/hcp_if.h
index 60ce02b..2c3c6e0 100644
--- a/drivers/infiniband/hw/ehca/hcp_if.h
+++ b/drivers/infiniband/hw/ehca/hcp_if.h

@@ -260,5 +260,6 @@ u64 hipz_h_error_data(const struct ipz_adapter_handle adapter_handle,
 		      const u64 ressource_handle,
 		      void *rblock,
 		      unsigned long *byte_count);
+u64 hipz_h_eoi(int irq);
 
 #endif /* __HCP_IF_H__ */

-- 
1.5.5

On Tue, 2008-06-10 at 16:44 +0200, Stefan Roscher wrote:

During corner case testing, we noticed that some versions of ehca 
do not properly transition to interrupt done in special load situations.
This can be resolved by periodically triggering EOI through H_EOI, 
if eqes are pending.

Signed-off-by: Stefan Roscher <redacted>

This patch is fine with me as long as the FW/HW people can confirm that
calling spurrious EOI's like that will not affect other interrupts.

The side effect of writing 0xff to the xirr should be irrelevant as long as
this is not done from within a HW interrupt handler (timer interrupts or
softirqs are fine).

Due to the already incestuous relationship between HCA and the hypervisor,
I don't mind having the H call directly in the driver.

So as long as the FW/HW people are ok with that workaround, then it has
my ack as well.

Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

Stefan Roscher writes:

During corner case testing, we noticed that some versions of ehca 
do not properly transition to interrupt done in special load situations.
This can be resolved by periodically triggering EOI through H_EOI, 
if eqes are pending.

Signed-off-by: Stefan Roscher <redacted>

If this is OKed by the hypervisor team, then you can add:
Acked-by: Paul Mackerras <redacted>

Paul.