Juerg, > > > + vt1211_write8(data, VT1211_REG_PWM_CTL, > > > + ((data->pwm_ctl[1] << 4) | > > > + data->pwm_ctl[0])); > > > + vt1211_write8(data, VT1211_REG_FAN_DIV, > > > + ((data->fan_div[1] << 6) | > > > + (data->fan_div[0] << 4) | > > > + data->fan_ctl)); > > > > BTW, here you don't actually care about the values of fan_div, all you > > need is to make sure you don't overwrite them in the register. In that > > case it isn't very efficient to decode them and store them in the > > cache, then shift and merge them again to recreate the register value. > > Instead you could store the upper nibble of the register value in a > > temporary variable, it'd be more efficient, and IMHO clearer. > > But if I don't update the cache I could end up with stale data on a > following read. If there is a back-to-back read-write-read sequence, > the 2nd read could return the cached value from the 1st read rather > then the updated value from the write. Sorry, I don't follow you here. Do you have a concrete example please? At any rate, this is only an optimization. If you don't feel comfortable with it, you can go on with your method which will still work. Thanks, -- Jean Delvare
