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SubjectRe: [PATCH v6 1/5] cpuidle: qcom_spm: Detach state machine from main SPM handling
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Il 22/06/21 14:04, Stephan Gerhold ha scritto:
> On Tue, Jun 22, 2021 at 01:39:15PM +0200, AngeloGioacchino Del Regno wrote:
>> Il 21/06/21 23:08, Stephan Gerhold ha scritto:
>>> On Mon, Jun 21, 2021 at 08:10:12PM +0200, AngeloGioacchino Del Regno wrote:
>>>> In commit a871be6b8eee ("cpuidle: Convert Qualcomm SPM driver to a generic
>>>> CPUidle driver") the SPM driver has been converted to a
>>>> generic CPUidle driver: that was mainly made to simplify the
>>>> driver and that was a great accomplishment;
>>>> Though, it was ignored that the SPM driver is not used only
>>>> on the ARM architecture.
>>>>
>>>
>>> I don't really understand why you insist on writing that I deliberately
>>> "ignored" your use case when converting the driver. This is not true.
>>> Perhaps that's not actually what you meant but that's how it sounds to
>>> me.
>>>
>>
>> So much noise for one single word. I will change it since it seems to be
>> that much of a deal, and I'm sorry if that hurt you in any way.
>>
>> For the records, though, I really don't see anything offensive in that,
>> and anyway I didn't mean to be offensive in any way.
>>
>
> I try to put a lot of thought into my patches to make sure I don't
> accidentally break some other use cases. Having that sentence in the
> commit log does indeed hurt me a bit since I would never deliberately
> disregard other use cases without making it absolutely clear in the
> patch.
>
> By using the word "ignored" ("deliberately not listen or pay attention
> to") [1] you say that I did, and that's why I would prefer if you
> reword this slightly. :)
>

As I said, I will reword it.

> [1] https://en.wiktionary.org/wiki/ignore
>
>>>> In preparation for the enablement of SPM features on AArch64/ARM64,
>>>> split the cpuidle-qcom-spm driver in two: the CPUIdle related
>>>> state machine (currently used only on ARM SoCs) stays there, while
>>>> the SPM communication handling lands back in soc/qcom/spm.c and
>>>> also making sure to not discard the simplifications that were
>>>> introduced in the aforementioned commit.
>>>>
>>>> Since now the "two drivers" are split, the SCM dependency in the
>>>> main SPM handling is gone and for this reason it was also possible
>>>> to move the SPM initialization early: this will also make sure that
>>>> whenever the SAW CPUIdle driver is getting initialized, the SPM
>>>> driver will be ready to do the job.
>>>>
>>>> Please note that the anticipation of the SPM initialization was
>>>> also done to optimize the boot times on platforms that have their
>>>> CPU/L2 idle states managed by other means (such as PSCI), while
>>>> needing SAW initialization for other purposes, like AVS control.
>>>>
>>>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
>>>> ---
>>>> drivers/cpuidle/Kconfig.arm | 1 +
>>>> drivers/cpuidle/cpuidle-qcom-spm.c | 324 +++++++----------------------
>>>> drivers/soc/qcom/Kconfig | 9 +
>>>> drivers/soc/qcom/Makefile | 1 +
>>>> drivers/soc/qcom/spm.c | 198 ++++++++++++++++++
>>>> include/soc/qcom/spm.h | 41 ++++
>>>> 6 files changed, 325 insertions(+), 249 deletions(-)
>>>> create mode 100644 drivers/soc/qcom/spm.c
>>>> create mode 100644 include/soc/qcom/spm.h
>>>>
>>>> diff --git a/drivers/cpuidle/cpuidle-qcom-spm.c b/drivers/cpuidle/cpuidle-qcom-spm.c
>>>> index adf91a6e4d7d..091453135ea6 100644
>>>> --- a/drivers/cpuidle/cpuidle-qcom-spm.c
>>>> +++ b/drivers/cpuidle/cpuidle-qcom-spm.c
>>>> [...]
>>>> +static int spm_cpuidle_register(int cpu)
>>>> {
>>>> + struct platform_device *pdev = NULL;
>>>> + struct device_node *cpu_node, *saw_node;
>>>> + struct cpuidle_qcom_spm_data data = {
>>>> + .cpuidle_driver = {
>>>> + .name = "qcom_spm",
>>>> + .owner = THIS_MODULE,
>>>> + .cpumask = (struct cpumask *)cpumask_of(cpu),
>>>> + .states[0] = {
>>>> + .enter = spm_enter_idle_state,
>>>> + .exit_latency = 1,
>>>> + .target_residency = 1,
>>>> + .power_usage = UINT_MAX,
>>>> + .name = "WFI",
>>>> + .desc = "ARM WFI",
>>>> + }
>>>> + }
>>>> + };
>>>
>>> The stack is gone after the function returns.
>>>
>>
>> Argh, I wrongly assumed that cpuidle was actually copying this locally.
>> Okay, let's see what else looking clean I can come up with.
>
> I guess you could just use a devm_kzalloc() and then have code similar
> to the previous one (data->cpuidle_driver = <template>). You could
> alternatively use devm_kmalloc() without zero-initialization but the
> advantages of that should be negligible.
>

Yes that would indeed work. It's just that I really don't like it.

> Thanks!
> Stephan
>

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