On 14 March 2017 17:36:16 GMT+00:00, Gargi Sharma <gs051095@xxxxxxxxx> wrote: >On Tue, Mar 14, 2017 at 2:24 AM, Lars-Peter Clausen <lars@xxxxxxxxxx> >wrote: >> On 03/13/2017 09:51 PM, Jonathan Cameron wrote: >> [...] >>>>> Gargi, >>>>> >>>>> Please insert the new lock above the __cacheline_aligned struct >>>>> member. >>>> >>>> I will do that, but is there any reason why the lock should be >above >>>> ____cacheline_aligned struct member? >>> Yes. It's in fact very important that nothing comes after that. >>> >>> Will leave the why as an exercise for the reader. I'll give the >>> hit of spi drivers that do DMA... >> >> >> One hint though, the answer is somewhere in Documentation/DMA-API.txt > >From what I have understood is that cacheline is used for keeping most >frequently accessed values in adjacent cachelines. Why? What does cache line actually mean? > We want the >cacheline_aligned at the end in the struct definition so as to avoid >any holes after the cacheline boundary. Nope. Try http://www.pebblebay.com/a-guide-to-using-direct-memory-access-in-embedded-systems-part-two/ (Hint, search for 'shares') >> >-- >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 -- Sent from my Android device with K-9 Mail. Please excuse my brevity. -- 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
