On Thu, 20 Dec 2012 16:30:36 +0100, Federico Vaga <federico.v...@gmail.com> wrote: > On Wednesday 19 December 2012 15:09:25 Grant Likely wrote: > > Not a good idea. sysfs is not a good place for operational > > interfaces. Please use the spi character devices for direct > > manipulation of the SPI configuration. > > Hello, > > Can you explain why it is not a good idea? I do not understand; what > is the advantage of ioctl through char device? Or what it the issue > with sysfs? > > Thank you very much
I'm cautious about adding operational interfaces to sysfs because it can be quite difficult to get the locking right. To begin with it splits up a single interface into multiple files, any of which can be held open by a process. Then there is the question of ordering of operations when there are multiple users. For instance, if there were two users, each of which using different transfer parameters, a sysfs interface doesn't provide any mechanism to group setting up the device with the transfer. These are lessons learned the hard way with the gpio sysfs abi. I don't want to get caught in the same trap for spi. g. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
