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Message-ID: <e85ad80f-af7d-4eaf-9d14-dff13451f7e5@wanadoo.fr>
Date: Sat, 2 Mar 2024 19:37:47 +0100
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 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.
CJ
>
> [0] https://elixir.bootlin.com/linux/latest/source/drivers/regulator/devres.c#L330
>
> I have tested with rtc suspend resume and did not find any issue with
> this.patch.
>
>>
>> CJ
>>
> Thanks
> -Anand
>
>
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