Rex-BC Chen <rex-bc.chen@xxxxxxxxxxxx> writes: > From: Jia-Wei Chang <jia-wei.chang@xxxxxxxxxxxx> > > In some MediaTek SoCs, like MT8183, CPU and CCI share the same power > supplies. Cpufreq needs to check if CCI devfreq exists and wait until > CCI devfreq ready before scaling frequency. > > - Add is_ccifreq_ready() to link CCI device to CPI, and CPU will start > DVFS when CCI is ready. > - Add platform data for MT8183. > > Signed-off-by: Jia-Wei Chang <jia-wei.chang@xxxxxxxxxxxx> The checks here are not enough, and will lead to unexpected behavior. IIUC, before doing DVFS, you're checking: 1) if the "cci" DT node is present and 2) if the driver for that device is bound If both those conditions are not met, you don't actually fail, you just silently do nothing in ->set_target(). As Angelo pointed out also, this is not a good idea, and will be rather confusing to users. The same thing would happen if the cci DT node was present, but the CCI devfreq driver was disabled. Silent failure would also be quite unexpected behavior. Similarily, if the cci DT node is not present at all (like it is in current upstream DT), this CPUfreq driver will silently do nothing. Not good. So, this patch needs to handle several scenarios: 1) CCI DT node not present In this case, the driver should still operate normally. With no CCI node, or driver there's no conflict. 2) CCI DT present/enabled but not yet bound In this case, you could return -EAGAIN as suggested by Angelo, or maybe better, it should do a deferred probe. 3) CCI DT present, but driver disabled This case is similar to (1), this driver should continue to work. Kevin
