On Wed, Jun 8, 2011 at 13:51, Kevin Hilman <khilman@xxxxxx> wrote:
[..]
>> the issue is as follows:
>> currently we dont do voltage transitions. when we do that
>> eventually(and my current code has an forked implementation of dvfs,
>> the following steps happen):
>> late_initcall(omap2_common_pm_late_init);
>> does pmic inits, omap_voltage_late_init, init_voltages and SR dev initialization
>>
>> without these, there is no way to transition MPU to proper voltage,
>> frequency combination. The requirement will have to be that
>> omap2-cpufreq.c allows for cpufreq transitions only after voltage and
>> clk layers are ready for transitions - if we ever want to do dvfs -
>> which we will eventually need to.
>
> Yes, I understand.
>
> But $SUBJECT patch is fixing this as an _init_ time ordering problem,
> What you're describing is a runtime requirement that doesn't exist until
> a DVFS transition is done. IOW, the requirement is that the voltage
> etc. layers have to be init'd before the first transition.
>
> So, rather than fix this with initcall ordering (which will have to be
> redone as things git moved and converted to modules), just create a type
> of late init function in this driver, which gets called on the first
> transition.
The tricky part ofcourse is for the registration - if we do the
registration, omap_cpu_init will get called once the registration
happens - no reason to stop it, which in turn triggers omap_target the
moment the governors are ready to do their thing. Is the following
what you are talking about? I am not completely sure how this helps..
diff --git a/arch/arm/mach-omap2/omap2plus-cpufreq.c
b/arch/arm/mach-omap2/omap2plus-cpufreq.c
index 77efcb0..8586df8 100644
--- a/arch/arm/mach-omap2/omap2plus-cpufreq.c
+++ b/arch/arm/mach-omap2/omap2plus-cpufreq.c
@@ -253,6 +253,11 @@ static struct cpufreq_driver omap_driver = {
.attr = omap_cpufreq_attr,
};
+static int __init omap_cpufreq_lateinit(void)
+{
+ return cpufreq_register_driver(&omap_driver);
+}
+
static int __init omap_cpufreq_init(void)
{
if (cpu_is_omap24xx()) {
@@ -277,8 +282,7 @@ static int __init omap_cpufreq_init(void)
pr_warning("%s: unable to get the mpu device\n", __func__);
return -EINVAL;
}
-
- return cpufreq_register_driver(&omap_driver);
+ return 0;
}
static void __exit omap_cpufreq_exit(void)
@@ -288,5 +292,6 @@ static void __exit omap_cpufreq_exit(void)
MODULE_DESCRIPTION("cpufreq driver for OMAP2PLUS SOCs");
MODULE_LICENSE("GPL");
+late_initcall(omap_cpufreq_lateinit);
module_init(omap_cpufreq_init);
module_exit(omap_cpufreq_exit);
Regards,
Nishanth Menon
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