On Fri, 22 Nov 2019 at 19:26, Lorenzo Pieralisi
[off-list ref] wrote:

On Mon, Nov 18, 2019 at 02:37:41PM +0100, Ulf Hansson wrote:

quoted

On Fri, 15 Nov 2019 at 18:30, Sudeep Holla [off-list ref] wrote:

quoted

On Tue, Oct 29, 2019 at 05:44:35PM +0100, Ulf Hansson wrote:

quoted

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, introduce a per CPU variable called domain_state and
implement two helper functions to read/write its value. Then let the
domain_state take precedence over the regular selected state, when entering
and idle state.

Finally, let's also avoid sprinkling the existing non-OSI path with
operations being specific for OSI.

Mostly looks good.

Thanks!

quoted

I am still wondering if we can keep all OSI related
info in the newly created structure and have psci_states outside it as
before. And I was think psci_enter_idle_state_pc and psci_enter_idle_state_osi
instead of single psci_enter_idle_state and assign/initialise state->enter
based on the mode chosen. I had to closer look now and looks like enter
is initialised in generic dt_idle_states. That said, what you have in this
patch also looks OK to me, was just trying to avoid access to the new
structure all together and keep the PC mode patch almost same as before
when suspending. I will see what Lorenzo thinks about this.

I did explore that approach a bit, but found it easier to go with what
I propose here. The most important point, in my view, is that in this
suggested approach only one if-check, "if (!data->dev)", is added to
the PC mode path compared to the original path. I think this should be
fine, right!?

I don't see why we should use data->dev at runtime when we can
have two separate idle enter functions and the detection can
be done at probe once for all instead of every idle entry.

The overhead is close to nought but the point is that it is
really not needed.

Alright, I will adopt our suggestion and override the assigned idle
enter callback, when we succeed to attach the cpu-device to its PM
domain.

Do you have any other thoughts about the series?

Kind regards
Uffe

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