Hi Viresh, On Thu, Jul 30, 2020 at 10:01:45AM +0200, Stephan Gerhold wrote: > The OPP core already has well-defined semantics to ensure required > OPPs/regulators are set before/after the frequency change, depending > on if we scale up or down. > > Similar requirements might exist for the order of required OPPs > when multiple power domains need to be scaled for a frequency change. > > For example, on Qualcomm platforms using CPR (Core Power Reduction), > we need to scale the VDDMX and CPR power domain. When scaling up, > MX should be scaled up before CPR. When scaling down, CPR should be > scaled down before MX. > > In general, if there are multiple "required-opps" in the device tree > I would expect that the order is either irrelevant, or there is some > dependency between the power domains. In that case, the power domains > should be scaled down in reverse order. > > This commit updates _set_required_opps() to set required OPPs in > reverse order when scaling down. > > Signed-off-by: Stephan Gerhold <[email protected]>
This patch does not apply anymore after the cleanup you pushed to opp/linux-next. I would be happy to send a v2 with that fixed. On my other OPP patch set you mentioned that you might apply these directly with some of your own changes - would you also prefer to do it yourself in this case or should I send a v2? Still looking for your feedback on both patch sets by the way! :) Thanks! Stephan > --- > Related discussion: > https://lore.kernel.org/linux-arm-msm/[email protected]/ > > The advantage of this approach is that the CPR driver does not need > to bother with the VDDMX power domain at all - the requirements > can be fully described within the device tree, see e.g. [1]. > An alternative option would be to modify the CPR driver to make these votes. > > [1]: > https://lore.kernel.org/linux-arm-msm/[email protected]/2-msm8916-vdd-mx.patch > --- > drivers/opp/core.c | 30 +++++++++++++++++++++--------- > 1 file changed, 21 insertions(+), 9 deletions(-) > > diff --git a/drivers/opp/core.c b/drivers/opp/core.c > index f7a476b55069..f93f551c911e 100644 > --- a/drivers/opp/core.c > +++ b/drivers/opp/core.c > @@ -799,7 +799,7 @@ static int _set_required_opp(struct device *dev, struct > device *pd_dev, > /* This is only called for PM domain for now */ > static int _set_required_opps(struct device *dev, > struct opp_table *opp_table, > - struct dev_pm_opp *opp) > + struct dev_pm_opp *opp, bool up) > { > struct opp_table **required_opp_tables = opp_table->required_opp_tables; > struct device **genpd_virt_devs = opp_table->genpd_virt_devs; > @@ -821,12 +821,24 @@ static int _set_required_opps(struct device *dev, > */ > mutex_lock(&opp_table->genpd_virt_dev_lock); > > - for (i = 0; i < opp_table->required_opp_count; i++) { > - pd_dev = genpd_virt_devs[i]; > + if (up) { > + /* Scaling up? Set required OPPs in normal order */ > + for (i = 0; i < opp_table->required_opp_count; i++) { > + pd_dev = genpd_virt_devs[i]; > > - ret = _set_required_opp(dev, pd_dev, opp, i); > - if (ret) > - break; > + ret = _set_required_opp(dev, pd_dev, opp, i); > + if (ret) > + break; > + } > + } else { > + /* Scaling down? Set required OPPs in reverse order */ > + for (i = opp_table->required_opp_count - 1; i >= 0; i--) { > + pd_dev = genpd_virt_devs[i]; > + > + ret = _set_required_opp(dev, pd_dev, opp, i); > + if (ret) > + break; > + } > } > mutex_unlock(&opp_table->genpd_virt_dev_lock); > > @@ -914,7 +926,7 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long > target_freq) > opp_table->regulator_enabled = false; > } > > - ret = _set_required_opps(dev, opp_table, NULL); > + ret = _set_required_opps(dev, opp_table, NULL, false); > goto put_opp_table; > } > > @@ -973,7 +985,7 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long > target_freq) > > /* Scaling up? Configure required OPPs before frequency */ > if (freq >= old_freq) { > - ret = _set_required_opps(dev, opp_table, opp); > + ret = _set_required_opps(dev, opp_table, opp, true); > if (ret) > goto put_opp; > } > @@ -993,7 +1005,7 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned > long target_freq) > > /* Scaling down? Configure required OPPs after frequency */ > if (!ret && freq < old_freq) { > - ret = _set_required_opps(dev, opp_table, opp); > + ret = _set_required_opps(dev, opp_table, opp, false); > if (ret) > dev_err(dev, "Failed to set required opps: %d\n", ret); > } > -- > 2.27.0 >
