Jonathan Cameron wrote on 2011-02-08: > On 02/08/11 09:32, Hennerich, Michael wrote: >> Jonathan Cameron wrote on 2011-02-07: >>> On 02/07/11 15:34, Hennerich, Michael wrote: >>>> Jonathan Cameron wrote on 2011-02-05: >>>>> This is very much the starting point for bashing the meter >>>>> drivers into shape. For now I've just removed most of the unused >>>>> code and >>> stubs. >>>> >>>> Instead of removing the stubs - I would rather prefer implementing >>> them. >>> I agree in the ideal case. But even then, it is much easier to >>> review a patch that adds this functionality from scratch than it is >>> to review one that relies on large amounts of existing dead code. >>>> But I think you're right this dead code is not going to be useful >>>> either. >>>> >>>>> I have also cleaned up spi bus handling. I may well have gotten >>>>> that bit wrong so please do take a look. In some cases this >>>>> involved turning one transfer into two so as to clarify what the >>>>> code was doing. This may cause issues if the spi bus drivers >>>>> don't play the game properly or as if I got the conversion wrong. >>>> >>>> Looks right - but I had to double check with the datasheet. The >>>> SPI write then read behavior is a bit undefined. In particular, >>>> what is shifted out on the MOSI pin during the receive part. >>>> >>>> Some implementations send zero/one or repeat the last word in the >>>> shift register, while others tristate MOSI. If the target slave >>>> device in questions also listens on MOSI while it drives MISO, >>>> unpredicted behavior my result. >>> Strange, I thought this was defined as always sending zero if not >>> provided. If not then I would suggest we point this inconsistency out >>> to the spi guys and fix it up in those implementations that don't >>> conform. Otherwise as you say, one needs to always specify the other >>> direction just to make sure nothing weird happens. All my testing is >>> on ancient pxa boards, so I know that they always send zeros and dump >>> whatever is recieved. >> >> This behavior is implemented in the SPI Master Controller Drivers, and >> not in the SPI Bus Core. I know in the past some machine dependant >> implementations did it wrong. However looking at the drivers today they >> all (at least the ones I looked at) send zero in case tx_buf is NULL. > Good. In that case shall I send this set on to Greg? Might as well get > the easy cleanups in place asap. Yeah please. Acked-by: Michael Hennerich <michael.hennerich@xxxxxxxxxx> Greetings, Michael -- Analog Devices GmbH Wilhelm-Wagenfeld-Str. 6 80807 Muenchen Sitz der Gesellschaft: Muenchen; Registergericht: Muenchen HRB 40368; Geschaeftsfuehrer:Dr.Carsten Suckrow, Thomas Wessel, William A. Martin, Margaret Seif -- 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
