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Date: Fri, 14 Aug 2009 10:01:34 +1000 From: John Williams <john.williams@...alogix.com> To: Linux Kernel list <linux-kernel@...r.kernel.org> Cc: John Linn <John.Linn@...inx.com>, Stephen Neuendorffer <stephen.neuendorffer@...inx.com>, David DeBonis <david.debonis@...inx.com>, Michal Simek <michal.simek@...alogix.com>, Grant Likely <grant.likely@...retlab.ca> Subject: GPIOLIB, GPIO_SYS and port-wide accesses Hi, As I see it the gpiolib and sysfs export insists on single bit accesses even on gpio pins that are located on the same physical device/port. A couple of years ago there was mention of port-wide accesses being a good thing: http://lkml.indiana.edu/hypermail/linux/kernel/0608.0/0731.html (towards the bottom) Did anything ever come of that? Per-bit access is pretty inflexible if you are driving a 7-segment display or 8-LED bar display, holding lots of file descriptors open etc, and lots of syscall overhead. sysfs syntax like $ echo "240-247" > export $ echo 255 > gpio240-247/direction (8-bit binary mask - output) $ echo 255 > gpio240-247/value (all ones) would be reasonably friendly, obviously the underlying gpiolib would have to have some notion of coupled ports. Any thoughts? John -- John Williams, PetaLogix - Linux Solutions for a Reconfigurable World w: www.petalogix.com p: +61-7-30090663 f: +61-7-30090663 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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