03.03.2012 01:21, Steinar H. Gunderson kirjoitti: > On Sat, Mar 03, 2012 at 12:42:19AM +0200, Marko Ristola wrote: >> I'm not happy with I2CDONE busy looping either. >> I've tried twice lately to swith into I2C IRQ, but those patches have caused I2CDONE timeouts. > > Note that there are already timeouts with the current polling code, but they > are ignored (my patch makes them at least be printed with verbose=5). I can't > immediately recall if it's on RACK, DONE or both. I think that occasional timeouts belong to the picture (RACK missing means: packet lost). If I2CDONE comes immediately when I2C command has been emitted, it is a driver software bug (some earlier I2C command). > >> Do my following I2C logic thoughts make any sense? > > Well, note first of all that I know next to nothing about I2C, and I've never > seen any hardware documentation on the Mantis card (is there any?). But > generally it makes sense to me, except that I've never heard of the demand of > radio silence for 10 ms before. Ok. Radio silence for 10 ms isn't your problem: when you have a FE_LOCK, 10 ms requirement is no more relevant. > >> There might be race conditions, that the driver possibly manages: >> 1. If two threads talk into DVB frontend, one could turn off the I2C gate, while the other is talking to DVB frontend. >> This would case lack of I2CRACK: only way to recover would be to turn >> the I2C gate on, and then redo the I2C transfer. > > Note that I've tried putting mutexes around the I2C functions, and it didn't > help on the I2C timeouts; however, that was largely on a single-character > level, so it might not be enough. (You can see these mutexes being commented > out in my patch.) I have now a new idea for what to try with I2C interrupts. It all depends, whether I understand the driver coding well enough. > > /* Steinar */ I have also a low interest for Mantis coding: Ideas come fast, and if the new code doesn't work right away, I back up the code somewhere and drop it. Some years ago during Summer Holiday time I could get something done and even patches got applied into Linux kernel. Marko Ristola -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
