Re: Question on using MSI in PCI driver

From: Roland Dreier
Date: Mon Jun 21 2004 - 22:57:49 EST


Jeff> You are breaking new ground by adding MSI support to a
Jeff> driver. I thank you for this -- alot -- but you should
Jeff> realize there will probably be a little bit of PCI core work
Jeff> necessary in order to get things the way you want them.

Yes, I noticed only a couple of hotplug drivers seem to be using MSI,
and no one is using multiple vector support. My motivation is
twofold. First, because my device can generate interrupts for
different reasons, and I'm noticing that doing the MMIO read to the
cause register is taking a lot of time, so I'm wondering whether
avoiding this by having separate MSI-X messages will be a win.
Second, for the fun of trying it :)

Jeff> Feel free to propose changes to the PCI core to accomodate
Jeff> your MSI driver.

First patch coming up now :)

- Roland


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