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Message-ID: <ed5153e1-f4de-4268-a9d0-e74b779d2587@wanadoo.fr>
Date: Fri, 5 Apr 2024 18:12:40 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Anand Moon <linux.amoon@...il.com>
Cc: Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
Alim Akhtar <alim.akhtar@...sung.com>, linux-usb@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 3/4] usb: dwc3: exynos: Use
devm_regulator_bulk_get_enable() helper function
Le 05/04/2024 à 08:10, Anand Moon a écrit :
> Hi Christophe, Krzysztof,
>
> On Mon, 4 Mar 2024 at 17:16, Anand Moon <linux.amoon@...il.com> wrote:
>>
>> Hi Christophe,
>>
>> On Sun, 3 Mar 2024 at 00:07, Christophe JAILLET
>> <christophe.jaillet@...adoo.fr> wrote:
>>>
>>> Le 02/03/2024 à 17:48, Anand Moon a écrit :
>>>> Hi Christophe,
>>>>
>>>> On Sat, 2 Mar 2024 at 21:20, Christophe JAILLET
>>>> <christophe.jaillet@...adoo.fr> wrote:
>>>>>
>>>>> Le 01/03/2024 à 20:38, Anand Moon a écrit :
>>>>>> Use devm_regulator_bulk_get_enable() instead of open coded
>>>>>> 'devm_regulator_get(), regulator_enable(), regulator_disable().
>>>>>>
>>>>>> Signed-off-by: Anand Moon <linux.amoon@...il.com>
>>>>>> ---
>>>>>> drivers/usb/dwc3/dwc3-exynos.c | 49 +++-------------------------------
>>>>>> 1 file changed, 4 insertions(+), 45 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/usb/dwc3/dwc3-exynos.c b/drivers/usb/dwc3/dwc3-exynos.c
>>>>>> index 5d365ca51771..7c77f3c69825 100644
>>>>>> --- a/drivers/usb/dwc3/dwc3-exynos.c
>>>>>> +++ b/drivers/usb/dwc3/dwc3-exynos.c
>>>>>> @@ -32,9 +32,6 @@ struct dwc3_exynos {
>>>>>> struct clk *clks[DWC3_EXYNOS_MAX_CLOCKS];
>>>>>> int num_clks;
>>>>>> int suspend_clk_idx;
>>>>>> -
>>>>>> - struct regulator *vdd33;
>>>>>> - struct regulator *vdd10;
>>>>>> };
>>>>>>
>>>>>> static int dwc3_exynos_probe(struct platform_device *pdev)
>>>>>> @@ -44,6 +41,7 @@ static int dwc3_exynos_probe(struct platform_device *pdev)
>>>>>> struct device_node *node = dev->of_node;
>>>>>> const struct dwc3_exynos_driverdata *driver_data;
>>>>>> int i, ret;
>>>>>> + static const char * const regulators[] = { "vdd33", "vdd10" };
>>>>>>
>>>>>> exynos = devm_kzalloc(dev, sizeof(*exynos), GFP_KERNEL);
>>>>>> if (!exynos)
>>>>>> @@ -78,27 +76,9 @@ static int dwc3_exynos_probe(struct platform_device *pdev)
>>>>>> if (exynos->suspend_clk_idx >= 0)
>>>>>> clk_prepare_enable(exynos->clks[exynos->suspend_clk_idx]);
>>>>>>
>>>>>> - exynos->vdd33 = devm_regulator_get(dev, "vdd33");
>>>>>> - if (IS_ERR(exynos->vdd33)) {
>>>>>> - ret = PTR_ERR(exynos->vdd33);
>>>>>> - goto vdd33_err;
>>>>>> - }
>>>>>> - ret = regulator_enable(exynos->vdd33);
>>>>>> - if (ret) {
>>>>>> - dev_err(dev, "Failed to enable VDD33 supply\n");
>>>>>> - goto vdd33_err;
>>>>>> - }
>>>>>> -
>>>>>> - exynos->vdd10 = devm_regulator_get(dev, "vdd10");
>>>>>> - if (IS_ERR(exynos->vdd10)) {
>>>>>> - ret = PTR_ERR(exynos->vdd10);
>>>>>> - goto vdd10_err;
>>>>>> - }
>>>>>> - ret = regulator_enable(exynos->vdd10);
>>>>>> - if (ret) {
>>>>>> - dev_err(dev, "Failed to enable VDD10 supply\n");
>>>>>> - goto vdd10_err;
>>>>>> - }
>>>>>> + ret = devm_regulator_bulk_get_enable(dev, ARRAY_SIZE(regulators), regulators);
>>>>>> + if (ret)
>>>>>> + return dev_err_probe(dev, ret, "Failed to enable regulators\n");
>>>>>>
>>>>>> if (node) {
>>>>>> ret = of_platform_populate(node, NULL, NULL, dev);
>>>>>> @@ -115,10 +95,6 @@ static int dwc3_exynos_probe(struct platform_device *pdev)
>>>>>> return 0;
>>>>>>
>>>>>> populate_err:
>>>>>> - regulator_disable(exynos->vdd10);
>>>>>> -vdd10_err:
>>>>>> - regulator_disable(exynos->vdd33);
>>>>>> -vdd33_err:
>>>>>> for (i = exynos->num_clks - 1; i >= 0; i--)
>>>>>> clk_disable_unprepare(exynos->clks[i]);
>>>>>>
>>>>>> @@ -140,9 +116,6 @@ static void dwc3_exynos_remove(struct platform_device *pdev)
>>>>>>
>>>>>> if (exynos->suspend_clk_idx >= 0)
>>>>>> clk_disable_unprepare(exynos->clks[exynos->suspend_clk_idx]);
>>>>>> -
>>>>>> - regulator_disable(exynos->vdd33);
>>>>>> - regulator_disable(exynos->vdd10);
>>>>>> }
>>>>>>
>>>>>> static const struct dwc3_exynos_driverdata exynos5250_drvdata = {
>>>>>> @@ -196,9 +169,6 @@ static int dwc3_exynos_suspend(struct device *dev)
>>>>>> for (i = exynos->num_clks - 1; i >= 0; i--)
>>>>>> clk_disable_unprepare(exynos->clks[i]);
>>>>>>
>>>>>> - regulator_disable(exynos->vdd33);
>>>>>> - regulator_disable(exynos->vdd10);
>>>>>
>>>>> Hi,
>>>>>
>>>>> Same here, I don't think that removing regulator_[en|dis]able from the
>>>>> suspend and resume function is correct.
>>>>>
>>>>> The goal is to stop some hardware when the system is suspended, in order
>>>>> to save some power.
>>>> Ok,
>>>>>
>>>>> Why did you removed it?
>>>>
>>>> As per the description of the function devm_regulator_bulk_get_enable
>>>>
>>>> * This helper function allows drivers to get several regulator
>>>> * consumers in one operation with management, the regulators will
>>>> * automatically be freed when the device is unbound. If any of the
>>>> * regulators cannot be acquired then any regulators that were
>>>> * allocated will be freed before returning to the caller.
>>>
>>> The code in suspend/resume is not about freeing some resources. It is
>>> about enabling/disabling some hardware to save some power.
>>>
>>> Think to the probe/remove functions as the software in the kernel that
>>> knows how to handle some hardawre, and the suspend/resume as the on/off
>>> button to power-on and off the electrical chips.
>>>
>>> When the system is suspended, the software is still around. But some
>>> hardware can be set in a low consumption mode to save some power.
>>>
>>> IMHO, part of the code you removed changed this behaviour and increase
>>> the power consumption when the system is suspended.
>>>
>>
>> You are correct, I have changed the regulator API from
>> devm_regulator_get_enable to devm_regulator_bulk_get_enable
>> which changes this behavior.
>> I will fix it in the next version.
>>
>>> CJ
>
> I could not find any example in the kernel to support
> devm_regulator_bulk_disable
> but here is my modified file.
>
> If you have any suggestions for this plz let me know.
I don't think that your approach is correct, and I don't think that the
proposed patch does what you expect it to do.
Calling a devm_ function in suspend/resume functions looks really
strange to me and is likely broken.
Especially here, devm_regulator_bulk_get_enable() in the resume function
allocates some memory that is not freed in
devm_regulator_bulk_disable(), because the API is not designed to work
like that. So this could generate a kind of memory leak.
*I think that the code is good enough as-is*, but if you really want to
change something, maybe:
- devm_regulator_get()+regulator_enable() in the probe could be
changed to devm_regulator_get_enable()
- the resume/suspend function should be left as-is with
regulator_disable()/regulator_ensable()
- remove regulator_disable() from the error handling path of the
probe and from the remove function.
I *think* it would work.
CJ
> -----8<----------8<----------
> diff --git a/drivers/usb/dwc3/dwc3-exynos.c b/drivers/usb/dwc3/dwc3-exynos.c
> index 6d07592ad022..2f808cb9a006 100644
> --- a/drivers/usb/dwc3/dwc3-exynos.c
> +++ b/drivers/usb/dwc3/dwc3-exynos.c
> @@ -34,6 +34,8 @@ struct dwc3_exynos {
> int suspend_clk_idx;
> };
>
> +static const char * const regulators[] = { "vdd33", "vdd10" };
> +
> static int dwc3_exynos_probe(struct platform_device *pdev)
> {
> struct dwc3_exynos *exynos;
> @@ -41,7 +43,6 @@ static int dwc3_exynos_probe(struct platform_device *pdev)
> struct device_node *node = dev->of_node;
> const struct dwc3_exynos_driverdata *driver_data;
> int i, ret;
> - static const char * const regulators[] = { "vdd33", "vdd10" };
>
> exynos = devm_kzalloc(dev, sizeof(*exynos), GFP_KERNEL);
> if (!exynos)
> @@ -166,6 +167,8 @@ static int __maybe_unused
> dwc3_exynos_suspend(struct device *dev)
> struct dwc3_exynos *exynos = dev_get_drvdata(dev);
> int i;
>
> + devm_regulator_bulk_disable(dev);
> +
> for (i = exynos->num_clks - 1; i >= 0; i--)
> clk_disable_unprepare(exynos->clks[i]);
>
> @@ -177,6 +180,11 @@ static int __maybe_unused
> dwc3_exynos_resume(struct device *dev)
> struct dwc3_exynos *exynos = dev_get_drvdata(dev);
> int i, ret;
>
> + ret = devm_regulator_bulk_get_enable(dev, ARRAY_SIZE(regulators),
> + regulators);
> + if (ret)
> + dev_err(dev, "Failed to enable regulators\n");
> +
> for (i = 0; i < exynos->num_clks; i++) {
> ret = clk_prepare_enable(exynos->clks[i]);
> if (ret) {
>
> To support these changes we need to export the
> devm_regulator_bulk_disable function.
> -----8<----------8<----------
> diff --git a/drivers/regulator/devres.c b/drivers/regulator/devres.c
> index 90bb0d178885..97eed739f929 100644
> --- a/drivers/regulator/devres.c
> +++ b/drivers/regulator/devres.c
> @@ -318,7 +318,7 @@ void devm_regulator_bulk_put(struct
> regulator_bulk_data *consumers)
> }
> EXPORT_SYMBOL_GPL(devm_regulator_bulk_put);
>
> -static void devm_regulator_bulk_disable(void *res)
> +void devm_regulator_bulk_disable(void *res)
> {
> struct regulator_bulk_devres *devres = res;
> int i;
> @@ -326,6 +326,7 @@ static void devm_regulator_bulk_disable(void *res)
> for (i = 0; i < devres->num_consumers; i++)
> regulator_disable(devres->consumers[i].consumer);
> }
> +EXPORT_SYMBOL_GPL(devm_regulator_bulk_disable);
>
> /**
> * devm_regulator_bulk_get_enable - managed get'n enable multiple regulators
> diff --git a/include/linux/regulator/consumer.h
> b/include/linux/regulator/consumer.h
> index 4660582a3302..ce7d28306b17 100644
> --- a/include/linux/regulator/consumer.h
> +++ b/include/linux/regulator/consumer.h
> @@ -214,6 +214,7 @@ int __must_check regulator_bulk_enable(int num_consumers,
> struct regulator_bulk_data *consumers);
> int devm_regulator_bulk_get_enable(struct device *dev, int num_consumers,
> const char * const *id);
> +void devm_regulator_bulk_disable(void *res);
> int regulator_bulk_disable(int num_consumers,
> struct regulator_bulk_data *consumers);
> int regulator_bulk_force_disable(int num_consumers,
> --------------------------------------------------------------------------
>
> Thanks
> -Anand
>
>
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