SCSI: lpfc, restore MSI-X/MSI support

From: George Kadianakis <desnacked {bomb} gmail {point} com>

A Gentoo bug report [1] showed that as of 2.6.31 lpfc only uses INTx interrupts.
This patch restores lpfc's ability to support MSI-X/MSI interrupts that the "Addition of SLI4 Interface - Base Support" patch [2] broke. It reestablishes MSI-X as the default interrupt method and in case MSI-X is not supported lpfc_sli{4,}_enable_intr fallbacks to MSI and then to INTx.

[1]: http://bugs.gentoo.org/show_bug.cgi?id=296319
[2]: commit da0436e915a5c17ee79e72c1bf978a4ebb1cbf4d

Signed-off-by George Kadianakis <desnacked {cat} gmail {dog} com>

---
 drivers/scsi/lpfc/lpfc_attr.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

drivers/scsi/lpfc/lpfc_attr.c +3 -3

index e1a30a1..936ecaf 100644
@@ -2890,12 +2890,12 @@ LPFC_ATTR_RW(poll_tmo, 10, 1, 255,
 /*
 # lpfc_use_msi: Use MSI (Message Signaled Interrupts) in systems that
 # 				 support this feature
-#       0  = MSI disabled (default)
+#       0  = MSI disabled
 #       1  = MSI enabled
-#       2  = MSI-X enabled
+#       2  = MSI-X enabled (default)
 # Value range is [0,2]. Default value is 0.
 */
-LPFC_ATTR_R(use_msi, 0, 0, 2, "Use Message Signaled Interrupts (1) or "
+LPFC_ATTR_R(use_msi, 2, 0, 2, "Use Message Signaled Interrupts (1) or "
 					      "MSI-X (2), if possible");
 
 /*

The short response:

Acked-by James Smart <[email protected]>

Background:
Nothing Broke. This was intended.

We had originally enabled MSI-X by default, but in qualification within the last 12 months, we encountered a major catch-22:

There were at least 4 platforms, from 2 major OEMs, that :
- Say they support MSI-X - platform routines work and act as if they do.
- We enable it, generate a test interrupt to check they really do deliver it, and it works.
- But shortly after attachment, the system hangs or loses interrupts, resulting in a bad system behavior.

Given the distro's picking up the 2.6.32 kernel, we had to stick with a default of MSI-X off, with user-enabled MSI-X as these platforms couldn't get fixed.

However, we're also now encountering platforms that require MSI-X and never INTx, so we must change. It's desired also for also for performance reasons.

So - now (2.6.33) is the right time to re-enable MSI-X by default.

-- james s

From: George Kadianakis <desnacked {bomb} gmail {point} com>

A Gentoo bug report [1] showed that as of 2.6.31 lpfc only uses INTx interrupts. This patch restores lpfc's ability to support MSI-X/MSI interrupts that the "Addition of SLI4 Interface - Base Support" patch [2] broke.
It reestablishes MSI-X as the default interrupt method and in case MSI-X is not supported lpfc_sli{4,}_enable_intr fallbacks to MSI and then to INTx.

[1]: http://bugs.gentoo.org/show_bug.cgi?id=296319
[2]: commit da0436e915a5c17ee79e72c1bf978a4ebb1cbf4d

Signed-off-by George Kadianakis <desnacked {cat} gmail {dog} com>

---
 drivers/scsi/lpfc/lpfc_attr.c |    6 +++---

 1 file changed, 3 insertions(+), 3 deletions(-)

drivers/scsi/lpfc/lpfc_attr.c +0 -0

index e1a30a1..936ecaf 100644

drivers/scsi/lpfc/lpfc_attr.c +1 -2

  */
-LPFC_ATTR_R(use_msi, 0, 0, 2, "Use Message Signaled Interrupts (1) or "
+LPFC_ATTR_R(use_msi, 2, 0, 2, "Use Message Signaled Interrupts (1) or "
                                              "MSI-X (2), if possible");
 
  /*
--

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From: George Kadianakis <desnacked {bomb} gmail {point} com>

A Gentoo bug report [1] showed that as of 2.6.31 lpfc only uses INTx interrupts. This patch restores lpfc's ability to support MSI-X/MSI interrupts that the "Addition of SLI4 Interface - Base Support" patch [2] broke.
It reestablishes MSI-X as the default interrupt method and in case MSI-X is not supported lpfc_sli{4,}_enable_intr fallbacks to MSI and then to INTx.

[1]: http://bugs.gentoo.org/show_bug.cgi?id=296319
[2]: commit da0436e915a5c17ee79e72c1bf978a4ebb1cbf4d

Signed-off-by George Kadianakis <desnacked {cat} gmail {dog} com>

 drivers/scsi/lpfc/lpfc_attr.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

drivers/scsi/lpfc/lpfc_attr.c +1 -1

index e1a30a1..936ecaf 100644
@@ -2890,12 +2890,12 @@ LPFC_ATTR_RW(poll_tmo, 10, 1, 255,
 /*
 # lpfc_use_msi: Use MSI (Message Signaled Interrupts) in systems that
 # 				 support this feature
-#       0  = MSI disabled (default)
+#       0  = MSI disabled

From: George Kadianakis <desnacked {bomb} gmail {point} com>

A Gentoo bug report [1] showed that as of 2.6.31 lpfc only uses INTx interrupts. This patch restores lpfc's ability to support MSI-X/MSI interrupts that the "Addition of SLI4 Interface - Base Support" patch [2] broke.
It reestablishes MSI-X as the default interrupt method and in case MSI-X is not supported lpfc_sli{4,}_enable_intr fallbacks to MSI and then to INTx.

[1]: http://bugs.gentoo.org/show_bug.cgi?id=296319
[2]: commit da0436e915a5c17ee79e72c1bf978a4ebb1cbf4d

Signed-off-by George Kadianakis <[email protected]>

---
 drivers/scsi/lpfc/lpfc_attr.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

drivers/scsi/lpfc/lpfc_attr.c +0 -0

index e1a30a1..936ecaf 100644