Kalle Valo wrote:
Tomas Winkler <tomasw@xxxxxxxxx> writes:
TBH, that confused me completely since the rate scale algorithm tells
the hardware what rate to use so why does the hw need to assign a
different rate in the tx status?
I see. Rate scale algorithm only tels FW from what rate to start
transmission. FW is responsible to do downscaling. Which is quite
reasonable as retransmission is real time process. Instead of
retransmitting on the same rate FW downscales. T X response provides
to the rate scaling algorithm the successful rate.
I just want to point out this is an important feature when the bus is
very slow, for example SPI bus in embedded devices. Retransfering
frames through SPI for every rate restransmit would make such a device
extremely slow.
I don't know of a part that does repeated DMA to implement retransmit;
do you have an example?
Regardless, the original issue is independent; good devices support
multi-rate retransmit so the final tx rate may not be the same as the
rate specified for the initial series. Whether this is done in fw or hw
doesn't matter.
Sam
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