Richard Weinberger writes: > Harald, > > Am 02.12.2014 um 11:19 schrieb Harald Geyer: > > Hi Richard, > > > > thanks for the patch. > > > > I think (haven't tried yet) that your patch changes the number of > > edges recorded per transmission. So probably the decoding function > > needs to be adapted too... > > Can you explain your thought? > I'll happily dig into that. Part of the reason to have the IRQ enabled during output was to get consistent timestamps (all timestamps would be taken via the same codepath). While this isn't essential, the current code expects that the start command we generate is in the list of edges. I think your changes will cause that start command not to be in the list of edges. Note: There have been issues with some sensors (DHT11s?) not to send proper start bits, so the driver tries to be liberal about what it expects and you probably haven't seen any decoding errors if your sample sensor works to specification. (Now that I come to think about it: Undefined behaviour of IRQs on output lines could have been involved too...) This is a bit of a mess and I'd rather clean this up than add more to it. Maybe I'm overly fussy about this, but it has bitten me in the past. Since it seems you have some interesst in working on these parts, let me mention an unrelated issue: The DHT22 stops sending data after a random time (think of days here) which AFAIK only can be worked around by power-cycling the sensor. I mean to add something for this to the driver but couln't make up my mind about what the proper ABI for this would be, so right now I'm using some userspace hack for this. (The issue was already discussed on the linux-iio mailing list a few month ago, if you want to look into this. Anyway: You have been warned ... ;) > > I won't be able to ACK this before testing on real HW. Of course > > confirmation that your changes work reliably on both DHT11 and DHT22 > > will do as well. The debuging code present in the initial submission > > of the driver might be helpful to anybody trying to verify the > > timing. > > I have only DHT22 sensors. Of course I've tested the driver with these. Ok, so I'll test DHT11 first. It would still be nice to confirm how many edges are recorded from DHT22 though. Thanks, Harald -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
