Lior David <liord@xxxxxxxxxxxxxx> writes: > 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) For calibration and manufacturing testing we have NL80211_CMD_TESTMODE, which is a vendor specific interface. > I think sysfs is a reasonable place for it. Wireless drivers really should not use sysfs. I guess there might be valid cases when using sysfs is ok but I can't really come up with anything right now. -- Kalle Valo
