Hi! On 07/10/12 21:47, Jean-Christophe PLAGNIOL-VILLARD wrote: >> +This creates a new block of GPIOs as a list of GPIO numbers with the >> specified >> +size which are accessible via the returned struct gpio_block and the >> accessor >> +functions described below. Please note that you need to request the GPIOs >> +separately via gpio_request(). An arbitrary list of globally valid GPIOs >> can be >> +specified, even ranging over several gpio_chips. Actual handling of I/O >> +operations will be done on a best effort base, i.e. simultaneous I/O only >> where >> +possible by hardware and implemented in the respective GPIO driver. The >> number >> +of GPIOs in one block is limited to 32 on a 32 bit system, and 64 on a 64 >> bit >> +system.
> this limitation is not acceptable I guess this depends on what you want to do. For practical reasons, accessing GPIOs collected in a word is reasonable, IMO. And according to the replies from Stijn and Linus, 32/64 bit words are acceptable for them. Can you please show me in which cases you need >32 bit word access (on a 32bit machine)? Practical example? Are there any GPIO controllers where you can actually get/set 32 lines simultaneously? Then, I'd be happy to adjust the API. (Actually, I liked Stijn's approach, which should be reflected in my patch.) If simultaneousness is not necessary, you can define further blocks with 32 lines each. Since your 32 bit machine will probably do only 32 bits maximum at once, I can't see a big limit here. Thanks for considering, Roland -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
