Re: [PATCH 07/18] drivers: firmware: psci: Prepare to use OS initiated suspend mode

From: Ulf Hansson
Date: Mon Jun 10 2019 - 06:26:10 EST

On Fri, 7 Jun 2019 at 17:17, Sudeep Holla <sudeep.holla@xxxxxxx> wrote:
> On Mon, May 13, 2019 at 09:22:49PM +0200, Ulf Hansson wrote:
> > The per CPU variable psci_power_state, contains an array of fixed values,
> > which reflects the corresponding arm,psci-suspend-param parsed from DT, for
> > each of the available CPU idle states.
> >
> > This isn't sufficient when using the hierarchical CPU topology in DT in
> > combination with having PSCI OS initiated (OSI) mode enabled. More
> > precisely, in OSI mode, Linux is responsible of telling the PSCI FW what
> > idle state the cluster (a group of CPUs) should enter, while in PSCI
> > Platform Coordinated (PC) mode, each CPU independently votes for an idle
> > state of the cluster.
> >
> > For this reason, let's introduce an additional per CPU variable called
> > domain_state and implement two helper functions to read/write its values.
> > Following patches, which implements PM domain support for PSCI, will use
> > the domain_state variable and set it to corresponding bits that represents
> > the selected idle state for the cluster.
> >
> > Finally, in psci_cpu_suspend_enter() and psci_suspend_finisher(), let's
> > take into account the values in the domain_state, as to get the complete
> > suspend parameter.
> >
> I understand it was split to ease review, but this patch also does
> nothing as domain_state = 0 always. I was trying hard to find where it's
> set, but I assume it will be done in later patches. Again may be this
> can be squashed into the first caller of psci_set_domain_state

You have a point, but I am worried that it would look like this series
is solely needed to support OSI mode. This is not the case. Let me

Having $subject patch separate shows the specific changes needed to
support OSI mode. The first caller of psci_set_domain_state() is added
in patch9, however, patch9 is useful no matter of OSI or PC mode.

Moreover, if I squash $subject patch with patch9, I would have to
squash also the subsequent patch (patch8), as it depends on $subject

So, to conclude, are you happy with this as is or do you want me to
squash the patches?

Kind regards