On 7/21/07, Nelson, Shannon <[EMAIL PROTECTED]> wrote:
Manu Abraham [mailto:[EMAIL PROTECTED]
>Sorry for being not clear. What i was asking is thus:
>
>A device that has legacy interrupts and MSI-X. I was thinking that if
>MSI-X failed one should fall back to MSI mode (single message), that's
>what i was assuming.
>
>In such a case, i do enable MSI-X mode on the device, when the request
>for 2 ^ n number of messages (where messages can be a max of 32), If
>the request fails one falls into a single message mode, ie MSI ?
>
>
>> What device do you have in mind?
>
>
>The device that i have in mind is a SAA7160.
Notice our code looks at the return from pci_enable_msix() - it will
give you a hint whether MSI-X is not supported (returns < 0) or you
simply asked for too many (returns > 0). If the former, then fallback
to legacy; if the latter, try MSI-X with only one interrupt, which
essentially emulates MSI mode.
Ok. Thanks for clearing it up. So the idea would be that if
pci_enable_msix() for "n" number of messages failed, then settle down
for 1 message, which is equivalent to MSI mode
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