On 02/24/2015 12:46 AM, Stephen Boyd wrote:
> On 02/06/15 10:58, Georgi Djakov wrote:
>> [...]
[..]
>> +
>> + /* Vote for GPLL0 to turn on */
>> + regmap_read(regmap, 0x45000, &val);
>> + val |= BIT(0);
>> + regmap_write(regmap, 0x45000, val);
>
> Hm.. I guess this is for the CPU to stay on, otherwise GPLL0 might turn
> off? But if we expose this register and the bit as gpll0_vote then we're
> going to turn it off once the last user turns off GPLL0. So I'm not sure
> how to handle this, but it certainly seems like we can just remove this
> bit of code and not be any worse off than we are right now. We need to
> figure out some way to make this work though.
>
Ok, agree.
> Here's the problem. GPLL0 is used by the CPU running this code. It's
> also used by random other clocks in the system. If the code for the CPU
> clock is not compiled in (i.e. clock-a53.c or whatever we call it), then
> it is very possible that we'll disable the last clock that's using the
> PLL according to what software knows, that will in turn disable the PLL
> and then the CPU will die.
>
> Of course, it's very possible that we'll never actually turn GPLL0 off
> because it's used for quite a few clocks in the system. So the chances
> of running into this problem are almost entirely theoretical.
Yes, I am investigating this scenario. Thanks for your comment.
>
>> +
>> + return qcom_cc_really_probe(pdev, &gcc_msm8916_desc, regmap);
>> +}
>> +
>> +static int gcc_msm8916_remove(struct platform_device *pdev)
>> +{
>> + qcom_cc_remove(pdev);
>> + return 0;
>> +}
>> +
>> +static struct platform_driver gcc_msm8916_driver = {
>> + .probe = gcc_msm8916_probe,
>> + .remove = gcc_msm8916_remove,
>> + .driver = {
>> + .name = "gcc-msm8916",
>
> We need owner = THIS_MODULE here because the platform_driver_module
> macro isn't being used.
>
But below i use the platform_driver_register macro and therefore it seems
not needed.
>> + .of_match_table = gcc_msm8916_match_table,
>> + },
>> +};
>> +
>> +static int __init gcc_msm8916_init(void)
>> +{
>> + return platform_driver_register(&gcc_msm8916_driver);
>> +}
>> +core_initcall(gcc_msm8916_init);
>> +
>> +static void __exit gcc_msm8916_exit(void)
>> +{
>> + platform_driver_unregister(&gcc_msm8916_driver);
>> +}
>> +module_exit(gcc_msm8916_exit);
>>
Thank you for taking a look at this preliminary stuff. I'll send in the
next few days updated and tested version.
BR,
Georgi
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