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SubjectRe: [PATCH v2 5/6] soc: qcom: rpmh powerdomain driver
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Hello Rajendra,

On 05/29/2018 03:19 AM, Rajendra Nayak wrote:
> On 05/26/2018 06:38 AM, David Collins wrote:
>> On 05/25/2018 03:01 AM, Rajendra Nayak wrote:
>>> The RPMh powerdomain driver aggregates the corner votes from various
...
>>> diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
>>> index a7a405178967..1faed239701d 100644
>>> --- a/drivers/soc/qcom/Kconfig
>>> +++ b/drivers/soc/qcom/Kconfig
>>> @@ -74,6 +74,15 @@ config QCOM_RMTFS_MEM
>>>
>>> Say y here if you intend to boot the modem remoteproc.
>>>
>>> +config QCOM_RPMHPD
>>> + tristate "Qualcomm RPMh Powerdomain driver"
>>
>> s/Qualcomm/Qualcomm Technologies, Inc./
>
> All other config options in qcom/Kconfig use 'Qualcomm XYZ feature'
> for the comment. Maybe I will leave it that way for consistency?

I don't have a strong opinion about it. I just want the legal folks to be
happy. I'm fine with whatever achieves that goal.


>>> +
>>> +struct rpmhpd_desc {
>>> + struct rpmhpd **rpmhpds;
>>> + size_t num_pds;
>>> +};
>>
>> This struct could be removed and the per-platform arrays could instead be
>> NULL terminated.
>
> Yes, but I would prefer it this way unless you have strong objections.
> Just makes it easier to do the allocations at probe for genpd_onecell_data structures.

I'm fine if you keep it as-is. I mentioned the alternative because
Stephen had requested the same modification on my qcom-rpmh-regulator
driver patch [1]. Other reviewers may care about this point.


>> Is there an API to determine the currently operating performance state of
>> a given power domain? Is this information accessible from userspace? We
>> will definitely need this for general debugging.
>
> A quick look shows me its not. I agree its a necessary feature for debug.
> I will add a patch to expose it via debugfs

Thanks


>>> +static int rpmhpd_probe(struct platform_device *pdev)
>>> +{
>>> + int i, ret;
>>> + size_t num;
>>> + struct genpd_onecell_data *data;
>>> + struct rpmhpd **rpmhpds;
>>> + const struct rpmhpd_desc *desc;
>>> +
>>> + desc = of_device_get_match_data(&pdev->dev);
>>> + if (!desc)
>>> + return -EINVAL;
>>> +
>>> + rpmhpds = desc->rpmhpds;
>>> + num = desc->num_pds;
>>> +
>>> + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
>>> + if (!data)
>>> + return -ENOMEM;
>>> +
>>> + data->domains = devm_kcalloc(&pdev->dev, num, sizeof(*data->domains),
>>> + GFP_KERNEL);
>>> + data->num_domains = num;
>>> +
>>> + ret = cmd_db_ready();
>>> + if (ret) {
>>> + if (ret != -EPROBE_DEFER)
>>> + dev_err(&pdev->dev, "Command DB unavailable, ret=%d\n",
>>> + ret);
>>> + return ret;
>>> + }
>>> +
>>> + for (i = 0; i < num; i++) {
>>> + if (!rpmhpds[i])
>>> + continue;
>>
>> Why is this check needed?
>
> Just to check/ignore if there are any holes.
> maybe I should atleast throw a warning instead of silently ignoring it?

A warning message might be a good idea if this condition should ever be
reached but also doesn't necessarily imply that probing must be ceased.
It looks like of_genpd_add_provider_onecell() ignores the NULL initialized
data->domains[i] values so it should be safe to leave the holes in and not
decrement num_domains accordingly.

Take care,
David

[1]: https://lkml.org/lkml/2018/3/21/681

--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

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