Hello, While doing some measurements, I am trying to detect the actual buffer on the wireless device (in this case AR5212). I couldn't find any datasheet that gives relevant details. By device buffer I don't mean the driver buffer or pending DMA requests, I rather mean the actual number of descriptors/packets that left the host's memory and reside at the device. I looked at two things : -Pending Frames Register : While I transmit data, this consistently reports 1. That said, I am not sure whether it reports the packets currently in the device or the unacknowledged packets in the air. - The second approach is more rough. I send a train of 50 packets which become pending DMA requests. I set the descriptors to transmit at a 6Mbps rate. I wait for time where at maximum one packet could possibly left the device. I go and change all the descriptors to send on a different rate. On a monitor device I check the packets in the air. Depending on which rate I see, I can figure out whether the descriptor had already left the device or not. I repeat the experiment for wait times of N packets as well. My preliminary understanding is that there is only one packet/descriptor DMA'ed on the device at any given time. When the packet is transmitted, the device will fetch the next one to transmit. Not clear whether this is triggered from a received ack, or AIFS of channel free. Could somebody comment on that? - Is indeed a per-packet transmission DMA fetch? - Also, do the trigger-levels apply only within a packet, or as long as you are below the TUNE_MAX_TXFIFO you can buffer multiple packets? Please let me know if you need more details on the setup. Thanks and Regards, -- Yiannis . -- 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
