Messages in this thread | | | Date | Mon, 22 Oct 2007 16:58:22 -0700 (PDT) | Subject | Re: [patch] PCI: disable MSI on more ATI NorthBridges | From | David Miller <> |
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From: Krzysztof Halasa <khc@pm.waw.pl> Date: Tue, 23 Oct 2007 01:40:18 +0200
> Jeff Garzik <jeff@garzik.org> writes: > > > In general it is documented that INTX_DISABLE should apply only to > > INTx# so devices that disable MSI based on that bit are out of spec. > > The wording is: > 10: This bit disables the device from asserting INTx#. A value of 0 > enables the assertion of its INTx# signal. A value of 1 disables the > assertion of its INTx# signal. This bit's state after RST# is 0. Refer > to Section 6.8.1.3 for control of MSI. > > So strictly speaking it mandates disabling/enabling INTx but says > nothing about other things (e.g. MSI). Some common sense dictates > it shouldn't disable MSI, I guess.
Right, and every vendor I've spoken to who had the INTX_DISABLE bug clearly acknowledged that it was a bug in their RTL design and that they considered the spec to be clear on this matter in that INTX_DISABLE should not influence MSI in any way.
> The "MSI Enable" description doesn't leave any doubt: > 0: MSI Enable: If 1, the function is permitted to use MSI to request > service and is prohibited from using its INTx# pin [...]
Things get more complicated with PCI-Express because INTx# isn't an out-of-band "pin", but rather a message sent over the bus :-) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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