On 1/19/2017 3:14 PM, Arend Van Spriel wrote: > On 19-1-2017 13:36, Lior David wrote: >> On 1/19/2017 2:24 PM, Valo, Kalle wrote: >>> Maya Erez <qca_merez@xxxxxxxxxxxxxxxx> writes: >>> >>>> From: Lior David <qca_liord@xxxxxxxxxxxxxxxx> >>>> >>>> In fine timing measurements, the calculation is affected by >>>> 2 parts: timing of packets over the air, which is platform >>>> independent, and platform-specific delays, which are dependent >>>> on things like antenna cable length and type. >>>> Add a sysfs file which allows to get/set these platform specific >>>> delays, separated into the TX and RX components. >>>> There are 2 key scenarios where the file can be used: >>>> 1. Calibration - start with some initial values (for example, >>>> the default values at startup), make measurements at a known >>>> distance, then iteratively change the values until the >>>> measurement results match the known distance. >>>> 2. Adjust the delays when platform starts up, based on known >>>> values. >>>> >>>> Signed-off-by: Lior David <qca_liord@xxxxxxxxxxxxxxxx> >>>> Signed-off-by: Maya Erez <qca_merez@xxxxxxxxxxxxxxxx> >>> >>> Can't this go via nl80211? sysfs is not really supposed to be used for >>> something like this. >>> >> There is no nl80211 API for this (yet?). > > So come up with one...? I checked this further and had some more internal discussion. This change is only about FTM calibration which is highly vendor specific so I don't think NL80211 API is appropriate for it. Since it is needed in production (to calibrate the platform after boot using pre-computed values), I think sysfs is a reasonable place for it. > >> Will it be ok to put this in debugfs? Normally this will be in the board >> file (as part of RF configuration) but it will be useful to play >> with these values for debugging/diagnostics. > > What is doing the FTM measurements? Is it all done in user-space? That > would mean you also need measurement data exported to user-space. How is > that done? Intel has a FTM api proposal, but it has not been submitted > upstream (yet?). > Our plan is to use the FTM API from intel once it is submitted upstream, but as I said this change is about FTM calibration which is separate from the generic FTM API. Thanks, Lior
