On Fri, 25 Sep 2020 at 08:08, Peng Fan <peng....@nxp.com> wrote: > > Hi Ulf, > > > Subject: [PATCH v2 3/3] PM / Domains: Add support for PM domain on/off > > notifiers for genpd > > > > A device may have specific HW constraints that must be obeyed to, before its > > corresponding PM domain (genpd) can be powered off - and vice verse at > > power on. These constraints can't be managed through the regular runtime > > PM based deployment for a device, because the access pattern for it, isn't > > always request based. In other words, using the runtime PM callbacks to deal > > with the constraints doesn't work for these cases. > > Could the notification be added before/after power on, and before/after power > off? not just after power on and before power off? > > Our SoC has a requirement that before power on/off the specific module, > the corresponding clk needs to be on to make sure the hardware async > bridge could finish handshake.
Thanks for your comments! May I ask, to be sure - does the clock correspond to the genpd provider or is it a clock for the genpd consumer device? If the former, couldn't the clock be managed from the ->power_on|off() callbacks for the genpd provider? > > So we need clk_prepare_on/off to guard power on and power off as below: > > clk_prepare_on > power on > clk_prepare_off > > clk_prepare_on > power off > clk_prepare_off > > Thanks, > Peng. > [...] Kind regards Uffe
