Hi David, I happen to be trying to achieve something very similar to what you are aiming at. I need to measure each TX frame's "service time", i.e. the interval of time between the instant this frame is considered for transmission and the instant the corresponding ACK is received or the transmission is given up (too many failed transmission attempts). Then I need this value to be returned to the kernel with the TX status, for further processing. Until now, I oversimplistically was doing that measurement upstream, in the kernel driver, taking a timestamp between the instant a frame is shipped through the USB framework and the instant the TX completion interrupt is received. This approach worked well only when sending sustained traffic (back-to-back frames), since the TX completion time of the previous frame was then used as the starting instant of the current frame. When frames were sent one-by-one, the measured interval was way too large (as a matter of fact, it was a lot smaller, while still too large, when I used the ar9170 firmware+driver), so as to become unusable. Since I discovered the carl9170 firmware+driver, I'm seriously thinking about implementing that measurement inside the firmware for much higher accuracy. I read with great interest the threads you started and wanted to ask whether you managed to advance in your quest. In the meantime, I continue to read carl9170 firmware code thoroughly to get a feeling of how things are going on in it. Ignacy -- Information wants to be beer, or something like that. -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
