Re: [PATCH v3 3/5] devfreq: exynos-bus: convert to use dev_pm_opp_set_rate()

[Chanwoo Choi <cwchoi00@gmail.com>]

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.

> > 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()

>
> 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
>


-- 
Best Regards,
Chanwoo Choi