Am 16.01.2016 um 13:53 schrieb Jonathan Cameron: > On 16/01/16 12:52, Jonathan Cameron wrote: >> On 12/01/16 20:17, Alexander Koch wrote: >>> Am 12.01.2016 um 20:27 schrieb Peter Meerwald-Stadler: >>>> On Tue, 12 Jan 2016, Alexander Koch wrote: >>>> >>>>> Enable operation of the TI OPT3001 light sensor without having an >>>>> interrupt line available to connect the INT pin to. >>>>> >>>>> In this operation mode, we issue a conversion request and simply wait >>>>> for the conversion time available as timeout value, determined from >>>>> integration time configuration and the worst-case time given in the data >>>>> sheet (sect. 6.5, table on p. 5): >>>>> >>>>> short integration time (100ms): 110ms + 3ms = 113ms >>>>> long integration time (800ms): 880ms + 3ms = 883ms >>>>> >>>>> This change is transparent as behaviour defaults to using the interrupt >>>>> method if an interrupt no. is configured via device tree. Interrupt-less >>>>> operation mode is performed when no valid interrupt no. is given. >>>> >>>> looks good, I'd rather use a bool for use_irq and the msecs_to_jiffies() >>>> call moved from the #define to the code (which is not strictly necessary >>>> for the patch) -- matter of taste >>> >>> Thanks - actually this is my first patch, so positive feedback much >>> appreciated! >>> >>> Concerning the bool for 'use_irq': I first had it that way but then >>> opted for the bit field of length 1 as I wasn't sure whether bool would >>> get optimized to the same level by the compiler. >> Bit fields are often less efficient as the compiler has to separate them out >> using shifts and masks. Also from a space point of view the data structure >> will be considerably padded anyway for a couple of reasons: >> 1) It contains u32 fields so will at least be padded to a multiple of u32. >> 2) Memory allocations may well be a good bit larger depending on exact >> sizes vs the blob levels available in the memory allocator. >> >> Basic rule of thumb - keep things simple and let the compiler do the work. >> So a bool is suitable here. >> >>> >>> I'm a bit irritated by your comment concerning the msecs_to_jiffies() >>> call, as my patch indeed moves this call from the #define to the code. >>> Did you mean it the other way round, then? >> Presumably ;) >>> My reason to move it was that I need to work with microseconds for the >>> IRQ-less operation mode, and jiffies are only required in one place for >>> the IRQ mode. >> Now perhaps the 'right' way to do this would be have been a precursor patch >> removing the define rather than lumping what is an an connected change (in >> many ways) in here. Overall I agree the change is worthwhile and trivial. >> As Peter said, it's a matter of taste! We both happen to disagree with him >> on this point. > > ps. Should have said that other than the bit field vs bool change, the patch > looks good to me. Okay then, so will send a v2 of the patch that includes this bool change, shortly. While I'm at it, maybe I should include a second refactoring commit that changes the other bitfield members of the opt3001-struct that are used as bool as well - namely 'ok_to_ignore_lock' and 'result_ready'. I hope this is okay. Best regards Alex > > Jonathan >>> >>> >> > Best regards >>> >>> lynix >>> >> >> -- >> 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 >> > -- 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
