patch-2.2.3 linux/drivers/scsi/README.ncr53c8xx

• Lines: 55
• Date: Sun Mar 7 10:13:23 1999
• Orig file: v2.2.2/linux/drivers/scsi/README.ncr53c8xx
• Orig date: Fri Jan 8 22:36:09 1999

diff -u --recursive --new-file v2.2.2/linux/drivers/scsi/README.ncr53c8xx linux/drivers/scsi/README.ncr53c8xx
@@ -4,7 +4,7 @@
 21 Rue Carnot
 95170 DEUIL LA BARRE - FRANCE
 
-22 November 1998
+14 February 1999
 ===============================================================================
 
 1.  Introduction
@@ -39,6 +39,7 @@
       14.2 Device names change when another controller is added
       14.3 Using only 8 bit devices with a WIDE SCSI controller.
       14.4 Possible data corruption during a Memory Write and Invalidate
+      14.5 IRQ sharing problems
 15. SCSI problem troubleshooting
 16. Synchonous transfer negotiation tables
       16.1 Synchronous timings for 53C875 and 53C860 Ultra-SCSI controllers
@@ -669,6 +670,10 @@
     irqm:0	always open drain
     irqm:1	same as initial settings (assumed BIOS settings)
     irqm:2	always totem pole
+    irqm:0x10	driver will not use SA_SHIRQ flag when requesting irq
+    irqm:0x20	driver will not use SA_INTERRUPT flag when requesting irq
+
+    (Bits 0x10 and 0x20 can be combined with hardware irq mode option)
 
 Reverse probe
     revprob:n   probe chip ids from the PCI configuration in this order:
@@ -1027,7 +1032,25 @@
 may only be needed under Linux when a scatter/gather list is not used and 
 when the SCSI DATA IN phase is reentered after a phase mismatch.
 
- 
+14.5 IRQ sharing problems
+
+When an IRQ is shared by devices that are handled by different drivers, it 
+may happen that one driver complains about the request of the IRQ having 
+failed. This may be due to one driver having requested the IRQ using the 
+SA_INTERRUPT flag but some other having requested the same IRQ without this 
+flag, or to one driver not having requested the IRQ with the SA_SHIRQ flag.
+
+By default, the ncr53c8xx driver requests IRQs with both the SA_INTERRUPT 
+and the SA_SHIRQ flag, but you can disable use of SA_INTERRUPT flags from 
+the boot command line by using the following option:
+
+                      ncr53c8xx=irqm:0x20
+
+If this does not fix the problem, then you may want to check how all other 
+drivers are requesting the IRQ and report the problem. Note that if at least 
+a single driver does not request the IRQ with the SA_SHIRQ flag (share IRQ), 
+then the request of the IRQ obviously will not succeed for all the drivers.
+
 15. SCSI problem troubleshooting
 
 Most SCSI problems are due to a non conformant SCSI bus or to buggy