Alan Cox wrote: > On Tue, 13 Mar 2012 20:04:09 +0800 > Daniel Kurtz <djkurtz@xxxxxxxxxxxx> wrote: >> Userspace can write a 24-bit value (encoded as a 6 character hex string) >> to the 'object' sysfs entry to modify a single byte of the object table. >> The hex string encodes a 3 bytes, in the following format: > > How is this locked against other users and updates of these table data ? > > I don't see how all the objects and their pointers and size are > guaranteedto always be valid in all the users you have ? The particular layout of the "objects" on the maxtouch chip only changes if there is a firmware upgrade (or between different models of chip). It's just a convenience to allow bits of functionality to be extended or replaced without getting in a mess of random register in different places, but it's not dynamic. In terms of arbitrating between different reads/writes - the I2C bus locking will handle most of it. To be entirely correct, I think there should be a mutex so that this interface couldn't be used whilst the chip is resetting, backing up or upgrading firmware. -- Nick Dyer Software Engineer, ITDev Ltd Hardware and Software Development Consultancy Website: http://www.itdev.co.uk -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
