On Mon, Mar 19, 2012 at 4:04 PM, Henrik Rydberg <rydberg@xxxxxxxxxxx> wrote: > > Hi Daniel, > > > 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: > > TTFFVV > > > > Where: > > TT = object type > > FF = object offset > > VV = byte value > > > > The object table is modified in device ram, which means the change is > > volatile, and will be overwritten on the next device reset. To make > > changes permanent, the new settings should be persisted in the device's > > Non-Voltatile Memory using the updatenv sysfs entry. > > > > Also, since the device driver initializes itself by reading some values > > from the object table, the entire driver may need to be unloaded and > > reloaded after writing the values for the driver to stay in sync. > > Whether > > this is required depends on exactly which values were updated. > > > > Signed-off-by: Daniel Kurtz <djkurtz@xxxxxxxxxxxx> > > --- > > Perhaps you could give an example of why this is needed? > > Thanks, > Henrik The idea is to allow a a device to be calibrated via userspace. The atmel devices have many registers for tuning properties of their firmware. This would be used, for example, to program an initial calibration on a factory floor, or, to tune a device at runtime. Currently, the only way devices are configured and calibrated is for a system integrator to embed the entire calibration in the kernel via a binary blob in platform_data. Thanks, -Daniel -- 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
