On Wed, Apr 17, 2019 at 01:12:34PM -0700, Guenter Roeck wrote: > On Wed, Apr 17, 2019 at 12:48:18PM -0700, Nicolin Chen wrote: > > On Wed, Apr 17, 2019 at 11:39:49AM -0700, Nicolin Chen wrote: > > > > > > Thinking about it ... does it even make sense to cache reg_config twice, > > > > or would it be better to just update the local copy and use regmap_write() > > > > to send it to the chip ? > > > > > > I remember the reason of adding the read-back was to prevent race > > > condition. But now we have mutex protections for all sysfs nodes, > > > maybe it's not necessary anymore. I will read the code carefully > > > and see if it's safe to remove it -- will do in a separate patch. > > > > I just recalled a second thought for the reason why I left them > > there as it'd logically require a copy to restore upon failure > > of regmap_write, that might not look so neat as the read-back: > > > > old_config = reg_config; > > reg_config &= mask; > > reg_config |= val; > > ret = regmap_write(reg_config); > > if (ret) { > > reg_config = old_config; > > return ret; > > } > > reg = (reg_config & mask) | val; > ret = regmap_write(reg); > if (ret) > return ret; > reg_config = reg; > > doesn't look that bad to me, and is much less costly. Okay. Will submit a change. Thanks