Hi Sumant, Thanks for the quick response! I don't believe we're having any issues with the mask - we're just trying to debug some issues we're having with some controllers with 2.6.17.13, and that's the only real semantic difference (other than crashdump mode) between RHEL 4 kernels and 2.6.17.13, and it spooked me that the changelog didn't mention that it was intentional... I really appreciate the response, it helps us eliminate possibilities and doubt. Thanks! Joe Patro, Sumant wrote: > Hello Joe, > > The mask value 0x1f is to mask out interrupts. The value in the > current kernel code is appropriate for all controllers that the driver > supports. > > Are you seeing any specific issue in driver with this mask > value? > > Regards, > > Sumant > > -----Original Message----- > From: Joe Malicki [mailto:jmalicki@xxxxxxxxxxxxx] > Sent: Wednesday, January 03, 2007 5:41 PM > To: Patro, Sumant > Cc: linux-poweredge@xxxxxxxx; Keith R. Baker; linux-scsi@xxxxxxxxxxxxxxx > Subject: megaraid_sas xscale interrupt mask? > > Hi Sumant, > > While trying to debug Dell PERC 5/i RAID controller problems we've been > having with the megaraid_sas driver, we've been inspecting differences > between the Red Hat EL 4 kernel (which Dell officially supports) versus > the stock Linux 2.6.17.13 driver we use. We found a very interesting > change, introduced into linux 2.6.16, that seems very odd to us: > > http://groups.google.com/group/fa.linux.kernel/browse_frm/thread/51f889b > d09bafd2d/cbbe2a30b8c2eb94?lnk=st&q=outbound_intr_mask+0x1f+0x00000001&r > num=1#cbbe2a30b8c2eb94 > > The title of the thread is "megaraid_sas: new template defined to > represent each type of controllers", and introduces this curious change: > > /** > * megasas_disable_intr - Disables interrupts > * @regs: MFI register set > */ > static inline void > megasas_disable_intr(struct megasas_register_set __iomem * regs) { > - u32 mask = readl(®s->outbound_intr_mask) & (~0x00000001); > + u32 mask = 0x1f; > writel(mask, ®s->outbound_intr_mask); > > /* Dummy readl to force pci flush */ > > Interrupts are enabled by writing "1" to the same register. > > Is there a specific reason for this? Is it possible that Dell PERC 5/i > controllers differ from LSI controllers in this respect? It seems odd > that this change would be introduced without any explanation for what > it's meant to do, so I am very curious if it could be an inadvertently > introduced bug that is causing some problems. > > Thanks! > Joe Malicki > - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
