RE: [PATCH]iwlan dma mapping read and write changes

[Yu, Fenghua]

>>> > >> Indeed the firmware/ucode write back to host memory to update retry
>>> > >> counter for APMDU packets. I'm not sure if this is needed for legacy
>>> > >> traffic, though.
>> > >
>> > >I don't think they can be seeing AMPDU packets since that is, well,
>> > >broken?
>> >
>> > Currently I'm not aware of any other cases where memory is accessed
>> > back but I may have not complete info.  Will be back with the answer
>> > tomorrow.
>>
>> I don't think it really matters, since AMPDU packets will be fixed soon,
>> and for those you know it's necessary (and the report says that under
>> some other circumstances it's also necessary). Unless there'd be some
>> benefit from using BIDI only when we know it'll be needed, and using
>> TODEV in the other cases?
>
>Or if there's a firmware bug.

>That's why it's better to clear the picture. 
>Fenghua
>What exact HW do you get this error?

This is Lenovo T400 wireless lan. Firmware version is 5.4.1.16. I think this issue happens on other platform/hw as well.

Thanks.

-Fenghua


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