Re: [PATCH v3 1/2] clk: mediatek: Introduce need_pm_runtime to mtk_clk_desc

AngeloGioacchino Del Regno
2024-02-26T11:16:19Z

Il 23/02/24 05:27, Chen-Yu Tsai ha scritto:
> On Mon, Jan 8, 2024 at 4:18 PM Pin-yen Lin <treapking@chromium.org> wrote:
>>
>> Introduce a new need_pm_runtime variable to mtk_clk_desc to indicate
>> this clock controller needs runtime PM for its operations.
>> Also do a runtime PM get on the clock controller during the
>> probing stage to workaround a possible deadlock.
>>
>> Signed-off-by: Pin-yen Lin <treapking@chromium.org>
>
> Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
>
> The patch itself looks fine.
>
> Besides the MT8183 MFG clock issues, we do actually need this for the
> MT8192 ADSP clock. Its power domain is not enabled by default.
>

...but on MT8195 the ADSP clock works - because the ADSP node exists.

This poses a question: should we make clock controllers depend on power domains,
or should we keep everything powered off (hence clocks down - no power consumption)
*unless* the user exists?

For the second one, this means that the *device* gets the power domain (adsp), and
not the clock controller (which clocks are effectively useless if there's no user).

Angelo

>> ---
>>
>> Changes in v3:
>> - Update the commit message and the comments before runtime PM call
>>
>> Changes in v2:
>> - Fix the order of error handling
>> - Update the commit message and add a comment before the runtime PM call
>>
>> drivers/clk/mediatek/clk-mtk.c | 19 +++++++++++++++++++
>> drivers/clk/mediatek/clk-mtk.h | 2 ++
>> 2 files changed, 21 insertions(+)
>>
>> diff --git a/drivers/clk/mediatek/clk-mtk.c b/drivers/clk/mediatek/clk-mtk.c
>> index 2e55368dc4d8..ba1d1c495bc2 100644
>> --- a/drivers/clk/mediatek/clk-mtk.c
>> +++ b/drivers/clk/mediatek/clk-mtk.c
>> @@ -13,6 +13,7 @@
>> #include <linux/of.h>
>> #include <linux/of_address.h>
>> #include <linux/platform_device.h>
>> +#include <linux/pm_runtime.h>
>> #include <linux/slab.h>
>>
>> #include "clk-mtk.h"
>> @@ -494,6 +495,18 @@ static int __mtk_clk_simple_probe(struct platform_device *pdev,
>> return IS_ERR(base) ? PTR_ERR(base) : -ENOMEM;
>> }
>>
>> +
>> + if (mcd->need_runtime_pm) {
>> + devm_pm_runtime_enable(&pdev->dev);
>> + /*
>> + * Do a pm_runtime_resume_and_get() to workaround a possible
>> + * deadlock between clk_register() and the genpd framework.
>> + */
>> + r = pm_runtime_resume_and_get(&pdev->dev);
>> + if (r)
>> + return r;
>> + }
>> +
>> /* Calculate how many clk_hw_onecell_data entries to allocate */
>> num_clks = mcd->num_clks + mcd->num_composite_clks;
>> num_clks += mcd->num_fixed_clks + mcd->num_factor_clks;
>> @@ -574,6 +587,9 @@ static int __mtk_clk_simple_probe(struct platform_device *pdev,
>> goto unregister_clks;
>> }
>>
>> + if (mcd->need_runtime_pm)
>> + pm_runtime_put(&pdev->dev);
>> +
>> return r;
>>
>> unregister_clks:
>> @@ -604,6 +620,9 @@ static int __mtk_clk_simple_probe(struct platform_device *pdev,
>> free_base:
>> if (mcd->shared_io && base)
>> iounmap(base);
>> +
>> + if (mcd->need_runtime_pm)
>> + pm_runtime_put(&pdev->dev);
>> return r;
>> }
>>
>> diff --git a/drivers/clk/mediatek/clk-mtk.h b/drivers/clk/mediatek/clk-mtk.h
>> index 22096501a60a..c17fe1c2d732 100644
>> --- a/drivers/clk/mediatek/clk-mtk.h
>> +++ b/drivers/clk/mediatek/clk-mtk.h
>> @@ -237,6 +237,8 @@ struct mtk_clk_desc {
>>
>> int (*clk_notifier_func)(struct device *dev, struct clk *clk);
>> unsigned int mfg_clk_idx;
>> +
>> + bool need_runtime_pm;
>> };
>>
>> int mtk_clk_pdev_probe(struct platform_device *pdev);
>> --
>> 2.43.0.472.g3155946c3a-goog
>>