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

From: Chanwoo Choi
Date: Thu Jul 25 2019 - 14:07:28 EST

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In reply to: Kamil Konieczny: "Re: [PATCH v3 3/5] devfreq: exynos-bus: convert to use dev_pm_opp_set_rate()"
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2019ë 7ì 25ì (ë) ìí 11:19, Kamil Konieczny
<k.konieczny@xxxxxxxxxxxxxxxxxxx>ëì ìì:
>
> 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. ìì 12:05, k.konieczny@xxxxxxxxxxxxxxxxxxx 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@xxxxxxxxxxxxxxxxxxx>
> >> ---
> >> 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

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