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Subject: Re: [PATCH v3 3/5] devfreq: exynos-bus: convert to use
 dev_pm_opp_set_rate()
To:     cwchoi00@gmail.com
Cc:     Chanwoo Choi <cw00.choi@samsung.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Kukjin Kim <kgene@kernel.org>,
        Kyungmin Park <kyungmin.park@samsung.com>,
        Mark Rutland <mark.rutland@arm.com>,
        MyungJoo Ham <myungjoo.ham@samsung.com>,
        Nishanth Menon <nm@ti.com>, Rob Herring <robh+dt@kernel.org>,
        Stephen Boyd <sboyd@kernel.org>,
        Viresh Kumar <vireshk@kernel.org>,
        devicetree <devicetree@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Linux PM list <linux-pm@vger.kernel.org>,
        linux-samsung-soc <linux-samsung-soc@vger.kernel.org>
From:   Kamil Konieczny <k.konieczny@partner.samsung.com>
Message-ID: <4f62d397-0f62-f81d-8b76-b73c6fbee93d@partner.samsung.com>
Date:   Thu, 25 Jul 2019 17:15:47 +0200
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Hi,

On 25.07.2019 16:53, Chanwoo Choi wrote:
> 2019년 7월 25일 (목) 오후 11:19, Kamil Konieczny
> <k.konieczny@partner.samsung.com>님이 작성:
>>
>> Hi Chanwoo,
>>
>> On 25.07.2019 12:17, Chanwoo Choi wrote:
>>> Hi Kamil,
>>>
>>> Looks good to me. But, I have some comment. Please check them.
>>
>> Thank you for review, please see answers below.
>>
>>> After this patch, exynos_bus_target is perfectly same with
>>> exynos_bus_passive_target. The exynos_bus_passive_target() could be removed.
>>
>> Ok, I will make it in separate patch to simplify review process.
> 
> I think you can just modify this patch without any separate patch.

Do you want me to send v5 with patch 5 squashed in patch 3 ?
 
>>> On 19. 7. 20. 오전 12:05, k.konieczny@partner.samsung.com wrote:
>>>> Reuse opp core code for setting bus clock and voltage. As a side
>>>> effect this allow useage of coupled regulators feature (required
>>>
>>> s/useage/usage ?
>>
>> Good catch, I will change it.
>>
>>>> for boards using Exynos5422/5800 SoCs) because dev_pm_opp_set_rate()
>>>> uses regulator_set_voltage_triplet() for setting regulator voltage
>>>> while the old code used regulator_set_voltage_tol() with fixed
>>>> tolerance. This patch also removes no longer needed parsing of DT
>>>> property "exynos,voltage-tolerance" (no Exynos devfreq DT node uses
>>>> it).
>>>>
>>>> Signed-off-by: Kamil Konieczny <k.konieczny@partner.samsung.com>
>>>> ---
>>>>  drivers/devfreq/exynos-bus.c | 143 +++++++++--------------------------
>>>>  1 file changed, 37 insertions(+), 106 deletions(-)
>>>>
>>>> diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c
>>>> index f391044aa39d..c2147b0912a0 100644
>>>> --- a/drivers/devfreq/exynos-bus.c
>>>> +++ b/drivers/devfreq/exynos-bus.c
>>>> @@ -25,7 +25,6 @@
>>>>  #include <linux/slab.h>
>>>>
>>>>  #define DEFAULT_SATURATION_RATIO    40
>>>> -#define DEFAULT_VOLTAGE_TOLERANCE   2
>>>>
>>>>  struct exynos_bus {
>>>>      struct device *dev;
>>>> @@ -37,9 +36,9 @@ struct exynos_bus {
>>>>
>>>>      unsigned long curr_freq;
>>>>
>>>> -    struct regulator *regulator;
>>>> +    struct opp_table *opp_table;
>>>> +
>>>>      struct clk *clk;
>>>> -    unsigned int voltage_tolerance;
>>>>      unsigned int ratio;
>>>>  };
>>>>
>>>> @@ -99,56 +98,23 @@ static int exynos_bus_target(struct device *dev, unsigned long *freq, u32 flags)
>>>>  {
>>>>      struct exynos_bus *bus = dev_get_drvdata(dev);
>>>>      struct dev_pm_opp *new_opp;
>>>> -    unsigned long old_freq, new_freq, new_volt, tol;
>>>>      int ret = 0;
>>>>
>>>> -    /* Get new opp-bus instance according to new bus clock */
>>>> +    /* Get correct frequency for bus. */
>>>>      new_opp = devfreq_recommended_opp(dev, freq, flags);
>>>>      if (IS_ERR(new_opp)) {
>>>>              dev_err(dev, "failed to get recommended opp instance\n");
>>>>              return PTR_ERR(new_opp);
>>>>      }
>>>>
>>>> -    new_freq = dev_pm_opp_get_freq(new_opp);
>>>> -    new_volt = dev_pm_opp_get_voltage(new_opp);
>>>>      dev_pm_opp_put(new_opp);
>>>>
>>>> -    old_freq = bus->curr_freq;
>>>> -
>>>> -    if (old_freq == new_freq)
>>>> -            return 0;
>>>> -    tol = new_volt * bus->voltage_tolerance / 100;
>>>> -
>>>>      /* Change voltage and frequency according to new OPP level */
>>>>      mutex_lock(&bus->lock);
>>>> +    ret = dev_pm_opp_set_rate(dev, *freq);
>>>> +    if (!ret)
>>>> +            bus->curr_freq = *freq;
>>>>
>>>> -    if (old_freq < new_freq) {
>>>> -            ret = regulator_set_voltage_tol(bus->regulator, new_volt, tol);
>>>> -            if (ret < 0) {
>>>> -                    dev_err(bus->dev, "failed to set voltage\n");
>>>> -                    goto out;
>>>> -            }
>>>> -    }
>>>> -
>>>> -    ret = clk_set_rate(bus->clk, new_freq);
>>>> -    if (ret < 0) {
>>>> -            dev_err(dev, "failed to change clock of bus\n");
>>>> -            clk_set_rate(bus->clk, old_freq);
>>>> -            goto out;
>>>> -    }
>>>> -
>>>> -    if (old_freq > new_freq) {
>>>> -            ret = regulator_set_voltage_tol(bus->regulator, new_volt, tol);
>>>> -            if (ret < 0) {
>>>> -                    dev_err(bus->dev, "failed to set voltage\n");
>>>> -                    goto out;
>>>> -            }
>>>> -    }
>>>> -    bus->curr_freq = new_freq;
>>>> -
>>>> -    dev_dbg(dev, "Set the frequency of bus (%luHz -> %luHz, %luHz)\n",
>>>> -                    old_freq, new_freq, clk_get_rate(bus->clk));
>>>> -out:
>>>>      mutex_unlock(&bus->lock);
>>>>
>>>>      return ret;
>>>> @@ -195,8 +161,8 @@ static void exynos_bus_exit(struct device *dev)
>>>>              dev_warn(dev, "failed to disable the devfreq-event devices\n");
>>>>
>>>>      clk_disable_unprepare(bus->clk);
>>>> -    if (bus->regulator)
>>>> -            regulator_disable(bus->regulator);
>>>> +    if (bus->opp_table)
>>>> +            dev_pm_opp_put_regulators(bus->opp_table);
>>>>
>>>>      dev_pm_opp_of_remove_table(dev);
>>>>  }
>>>> @@ -209,39 +175,23 @@ static int exynos_bus_passive_target(struct device *dev, unsigned long *freq,
>>>>  {
>>>>      struct exynos_bus *bus = dev_get_drvdata(dev);
>>>>      struct dev_pm_opp *new_opp;
>>>> -    unsigned long old_freq, new_freq;
>>>> -    int ret = 0;
>>>> +    int ret;
>>>>
>>>> -    /* Get new opp-bus instance according to new bus clock */
>>>> +    /* Get correct frequency for bus. */
>>>>      new_opp = devfreq_recommended_opp(dev, freq, flags);
>>>>      if (IS_ERR(new_opp)) {
>>>>              dev_err(dev, "failed to get recommended opp instance\n");
>>>>              return PTR_ERR(new_opp);
>>>>      }
>>>>
>>>> -    new_freq = dev_pm_opp_get_freq(new_opp);
>>>>      dev_pm_opp_put(new_opp);
>>>>
>>>> -    old_freq = bus->curr_freq;
>>>> -
>>>> -    if (old_freq == new_freq)
>>>> -            return 0;
>>>> -
>>>>      /* Change the frequency according to new OPP level */
>>>>      mutex_lock(&bus->lock);
>>>> +    ret = dev_pm_opp_set_rate(dev, *freq);
>>>> +    if (!ret)
>>>> +            bus->curr_freq = *freq;
>>>>
>>>> -    ret = clk_set_rate(bus->clk, new_freq);
>>>> -    if (ret < 0) {
>>>> -            dev_err(dev, "failed to set the clock of bus\n");
>>>> -            goto out;
>>>> -    }
>>>> -
>>>> -    *freq = new_freq;
>>>> -    bus->curr_freq = new_freq;
>>>> -
>>>> -    dev_dbg(dev, "Set the frequency of bus (%luHz -> %luHz, %luHz)\n",
>>>> -                    old_freq, new_freq, clk_get_rate(bus->clk));
>>>> -out:
>>>>      mutex_unlock(&bus->lock);
>>>>
>>>>      return ret;
>>>> @@ -259,20 +209,9 @@ static int exynos_bus_parent_parse_of(struct device_node *np,
>>>>                                      struct exynos_bus *bus)
>>>>  {
>>>>      struct device *dev = bus->dev;
>>>> -    int i, ret, count, size;
>>>> -
>>>> -    /* Get the regulator to provide each bus with the power */
>>>> -    bus->regulator = devm_regulator_get(dev, "vdd");
>>>> -    if (IS_ERR(bus->regulator)) {
>>>> -            dev_err(dev, "failed to get VDD regulator\n");
>>>> -            return PTR_ERR(bus->regulator);
>>>> -    }
>>>> -
>>>> -    ret = regulator_enable(bus->regulator);
>>>> -    if (ret < 0) {
>>>> -            dev_err(dev, "failed to enable VDD regulator\n");
>>>> -            return ret;
>>>> -    }
>>>> +    struct opp_table *opp_table;
>>>> +    const char *vdd = "vdd";
>>>> +    int i, count, size;
>>>>
>>>>      /*
>>>>       * Get the devfreq-event devices to get the current utilization of
>>>> @@ -281,26 +220,29 @@ static int exynos_bus_parent_parse_of(struct device_node *np,
>>>>      count = devfreq_event_get_edev_count(dev);
>>>>      if (count < 0) {
>>>>              dev_err(dev, "failed to get the count of devfreq-event dev\n");
>>>> -            ret = count;
>>>> -            goto err_regulator;
>>>> +            return count;
>>>>      }
>>>> -    bus->edev_count = count;
>>>>
>>>> +    bus->edev_count = count;
>>>>      size = sizeof(*bus->edev) * count;
>>>>      bus->edev = devm_kzalloc(dev, size, GFP_KERNEL);
>>>> -    if (!bus->edev) {
>>>> -            ret = -ENOMEM;
>>>> -            goto err_regulator;
>>>> -    }
>>>> +    if (!bus->edev)
>>>> +            return -ENOMEM;
>>>>
>>>>      for (i = 0; i < count; i++) {
>>>>              bus->edev[i] = devfreq_event_get_edev_by_phandle(dev, i);
>>>> -            if (IS_ERR(bus->edev[i])) {
>>>> -                    ret = -EPROBE_DEFER;
>>>> -                    goto err_regulator;
>>>> -            }
>>>> +            if (IS_ERR(bus->edev[i]))
>>>> +                    return -EPROBE_DEFER;
>>>> +    }
>>>> +
>>>> +    opp_table = dev_pm_opp_set_regulators(dev, &vdd, 1);
>>>> +    if (IS_ERR(opp_table)) {
>>>> +            i = PTR_ERR(opp_table);
>>>> +            dev_err(dev, "failed to set regulators %d\n", i);
>>>> +            return i;
>>>
>>> Maybe, you just used the 'i' defined variable instead of adding
>>> new variable. But, I think that you better to add new variable
>>> like 'err' for the readability. Or, jut use the 'PTR_ERR(opp_table)'
>>> directly without any additional variable.
>>
>> I will remove not related changes, so here I will reuse 'ret' variable.
>>
>>>>      }
>>>>
>>>> +    bus->opp_table = opp_table;
>>>
>>> Add blank line.
>>
>> OK
>>
>>>>      /*
>>>>       * Optionally, Get the saturation ratio according to Exynos SoC
>>>>       * When measuring the utilization of each AXI bus with devfreq-event
>>>> @@ -314,16 +256,7 @@ static int exynos_bus_parent_parse_of(struct device_node *np,
>>>>      if (of_property_read_u32(np, "exynos,saturation-ratio", &bus->ratio))
>>>>              bus->ratio = DEFAULT_SATURATION_RATIO;
>>>>
>>>> -    if (of_property_read_u32(np, "exynos,voltage-tolerance",
>>>> -                                    &bus->voltage_tolerance))
>>>> -            bus->voltage_tolerance = DEFAULT_VOLTAGE_TOLERANCE;
>>>> -
>>>>      return 0;
>>>> -
>>>> -err_regulator:
>>>> -    regulator_disable(bus->regulator);
>>>> -
>>>> -    return ret;
>>>>  }
>>>>
>>>>  static int exynos_bus_parse_of(struct exynos_bus *bus)
>>>> @@ -414,12 +347,8 @@ static int exynos_bus_probe(struct platform_device *pdev)
>>>>
>>>>      /* Parse the device-tree to get the resource information */
>>>>      ret = exynos_bus_parse_of(bus);
>>>> -    if (ret < 0) {
>>>> -            if (!passive)
>>>> -                    regulator_disable(bus->regulator);
>>>> -
>>>> -            return ret;
>>>> -    }
>>>> +    if (ret < 0)
>>>> +            goto err_reg;
>>>>
>>>>      if (passive)
>>>>              goto passive;
>>>> @@ -512,10 +441,12 @@ static int exynos_bus_probe(struct platform_device *pdev)
>>>>
>>>>  err:
>>>>      clk_disable_unprepare(bus->clk);
>>>> -    if (!passive)
>>>> -            regulator_disable(bus->regulator);
>>>> -
>>>>      dev_pm_opp_of_remove_table(dev);
>>>
>>> This function removes the 'opp_table'. But, the below code
>>> uses the 'opp_table' variable by dev_pm_opp_put_regulators().
>>>
>>> To disable the regulator, you have to call dev_pm_opp_of_remove_table(dev)
>>> after dev_pm_opp_put_regulators(bus->opp_table).
>>
>> Regulators should be set before dev_pm_opp_add_table(), so exit sequence
>> should be in reverse order,
>>
>> init order:
>>
>> exynos_bus_parent_parse_of()
>>         dev_pm_opp_set_regulators()
>> exynos_bus_parse_of()
>>         clk_prepare_enable()
>>         dev_pm_opp_of_add_table()
>>
>> exit or error order:
>>
>> dev_pm_opp_of_remove_table()
>> clk_disable_unprepare()
>> if (bus->opp_table)
>>         dev_pm_opp_put_regulators(bus->opp_table);
> 
> dev_pm_opp_of_remove_table() have to be called at the end of exit sequence
> after disabling clock and put regulators. Because dev_pm_opp_of_remove_table()
> frees the 'opp_table' pointer of device.
> 
> clk_disable_unprepare()
> if (bus->opp_table)
>           dev_pm_opp_put_regulators(bus->opp_table);
> dev_pm_opp_of_remove_table()

The table is reference counted so it will be freed after count go to zero.

>> I will send v4 soon.
>>
>>>> +err_reg:
>>>> +    if (bus->opp_table) {
>>>> +            dev_pm_opp_put_regulators(bus->opp_table);
>>>> +            bus->opp_table = NULL;
>>>> +    }
>>>>
>>>>      return ret;
>>>>  }

-- 
Best regards,
Kamil Konieczny
Samsung R&D Institute Poland