Hi, On 02/22/2017 08:20 PM, Alexandre Macabies wrote: > Hello, > > This is not a formal patch. I am trying to add timestamping support to > the drivers/net/ieee802154/mrf24j40.c driver. I need more precise > timestamps that the software ones attached to the packets when > entering/leaving the kernel. > > As far as I am aware, the MRF24J40 has no registers[1] to retrieve > hardware timestamps. Thus the idea is to use ktime_get() timestamps at > the proper places in the driver -- hence the *pseudo*-hardware. > Sometimes e.g. at86rf230 has interrupts for that. > - for incoming packets, call ktime_get() in the interrupt handler and > store it for later user. Then push it to skb_hwtstamps just before > sending the skb to ieee802154_rx_irqsafe(). > - for outgoing packets, call ktime_get() in the "TX complete" > interrupt handler. This interrupt will only be triggered if the packet > is indeed going out the physical radio, which may no always be the > case, eg. if we send raw garbage on the wpan interface. But I guess > this is fine. > > I implemented these changes according to [2] and by looking at existing > timestamping code in other (mostly ethernet) drivers. > > Does this method make any sense? Could you do a review of my changes? > Would you be interested in up-streaming these changes once reviewed and > cleaned up? > question: does it work for you use case? :-) I think it's looking small enough to fit make a minimal implementation for such tx timestamping for all other users which looking for such feature. My question would also be: Do you can move such handling into ieee802154 subsystem? Add some functions to mac802154/util.c (should be fine at first, maybe we need another file if we get hardmac support). Then offer some API that others driver know when calling timestamp function (in a very abstract way). For me: TX start is when you set some bit to transmit finally the frame. TX end if when you know that the interrupt was a "tx done" irq. That's what I see you currently have done in the driver and makes sense to me. (Adding alan, the maintainer of the driver) - Alex -- To unsubscribe from this list: send the line "unsubscribe linux-wpan" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
