On 12/02/2014 04:35 PM, Lina Iyer wrote:
On Tue, Dec 02 2014 at 02:53 -0700, Daniel Lezcano wrote:
On 12/01/2014 07:50 PM, Lina Iyer wrote:
On Thu, Nov 27 2014 at 01:52 -0700, Daniel Lezcano wrote:
On 11/27/2014 06:24 AM, Lina Iyer wrote:
+ static bool cpuidle_drv_init;
^^^^^^^^^
As already said in a previous comment, please find a way to remove
that.
I will look into it. Stephen and I wanted the cpuidle driver to be
probed only after any of the SPMs are ready. And possibly, only for that
cpu, for which the SPM has been probed.
To achieve the SPM -> CPUIDLE Device relation, I havent found a good way
to do that. Without using CPUIDLE_MULTIPLE_DRIVERS, initializing each
cpuidle device, separate from the cpuidle driver, requires that I update
the cpuidle_driver->cpumask after probing each SPM device, to allow for
only one driver and cpuidle devices only for the probed cpus. Using the
cpuidle_register_driver(), resets the drv->refcnt in
__cpuidle_driver_init.
I may need something like this in the else clause of
CPUIDLE_MULTIPLE_DRIVERS -
static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
{
struct cpuidle_driver *drv = cpuidle_curr_driver;
if (drv && !cpumask_test_cpu(cpu, drv->cpumask))
drv = NULL;
return drv;
}
You don't have to deal with the drv->cpumask and
CPUIDLE_MULTIPLE_DRIVERS. This field gives the list of the cpus the
driver will have to potentially handle.
Just register the driver at the first place with the platform device
by using cpuidle_register_driver(drv), I suggest somewhere else than
the spm code.
The underlying code will do:
if (!drv->cpumask)
drv->cpumask = (struct cpumask *)cpu_possible_mask;
Until the cpuidle device is not initialized for a specific cpu, the
cpuidle code will have no effect for this cpu. If you register the
driver but without registering the cpuidle devices that will result in
nothing more than a structure initialized but inoperative.
For each SPM being probed:
struct cpuidle_device *dev = &per_cpu(cpuidle_dev, cpu);
dev->cpu = cpu;
cpuidle_register_device(dev);
Note cpuidle_dev is exported via cpuidle.h, so you don't have to
redeclare a per cpu cpuidle device by your own.
So rephrasing all that:
(1) in cpuidle-qcom register the driver
(2) in the spm code register the device for each spm probe
(1) being called before (2).
If after that in the code you still have a "static bool
cpuidle_drv_init", then I guess we have a problem in the init sequence
somewhere else.
Okay, Thanks. Last night I was able to get a patch working with one
cpuidle_register_driver and multiple cpuidle_register_device. The issue
using an module_init() was -
1. Register a device to probe the cpuidle driver.
2. Register cpuidle devices for every SPM probed.
That's it.
What used to happen is that the cpuidle driver probe always happens
after the cpuidle devices were created.
I have a solution where I register for the cpuidle device to probe a
driver, at postcore_initcall() at which point, the cpuidle framework
would also be available.
I am not sure how elegant it looks, but thats the latest initcall I
could get a consistent driver initialization before the SPM probe
(therefore the device registration).
I don't have the code in front of me but we can probably find a nice
place to probe the cpuidle driver. Is there any pm.c file with an init
function that can be useful ? In any case, regarding the unusual init
sequence for the cpuidle driver, I think the probe would deserve a comment.
I will send the patch this morning.
Ok, cool.
[ ... ]
There is something wrong with the init sequence. Don't you find weird
you have to backward search for the cpu belonging to the pdev each
time the probe function is called ?
Well, it was that or the SPM device node pointing to the CPU that it
references. It seems more common to have an iterator than the doubly
linked device nodes. I dont have a strong preference either way, just
chose the way that made device nodes easier.
This one, I havent addressed. How strongly do you feel about this? I
still have to iterate through all the cpus to find the cpu node that
matches the handle specified in the SAW node.
IMO, we can live with that if there is no longer any static variable
around telling us we initialized something.
Thanks !
-- Daniel
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