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Date: Thu, 25 Jul 2019 18:58:43 +0900
From: Chanwoo Choi <cw00.choi@...sung.com>
To: k.konieczny@...tner.samsung.com
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Krzysztof Kozlowski <krzk@...nel.org>,
Kukjin Kim <kgene@...nel.org>,
Kyungmin Park <kyungmin.park@...sung.com>,
Mark Rutland <mark.rutland@....com>,
MyungJoo Ham <myungjoo.ham@...sung.com>,
Nishanth Menon <nm@...com>, Rob Herring <robh+dt@...nel.org>,
Stephen Boyd <sboyd@...nel.org>,
Viresh Kumar <vireshk@...nel.org>, devicetree@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-pm@...r.kernel.org, linux-samsung-soc@...r.kernel.org
Subject: Re: [PATCH v3 1/5] devfreq: exynos-bus: correct clock enable
sequence
Hi Kamil,
On 19. 7. 20. 오전 12:05, k.konieczny@...tner.samsung.com wrote:
> Regulators should be enabled before clocks to avoid h/w hang. This
> require change in exynos_bus_probe() to move exynos_bus_parse_of()
> after exynos_bus_parent_parse_of() and change in enabling sequence
> of regulator and clock in exynos_bus_parse_of(). Similar change is
> needed in exynos_bus_exit() where clock should be disabled first.
>
> Signed-off-by: Kamil Konieczny <k.konieczny@...tner.samsung.com>
> ---
> This patch is new to this series.
>
> ---
> drivers/devfreq/exynos-bus.c | 58 ++++++++++++++++++++----------------
> 1 file changed, 32 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c
> index 486cc5b422f1..f391044aa39d 100644
> --- a/drivers/devfreq/exynos-bus.c
> +++ b/drivers/devfreq/exynos-bus.c
> @@ -194,11 +194,11 @@ static void exynos_bus_exit(struct device *dev)
> if (ret < 0)
> dev_warn(dev, "failed to disable the devfreq-event devices\n");
>
> + clk_disable_unprepare(bus->clk);
> if (bus->regulator)
> regulator_disable(bus->regulator);
>
> dev_pm_opp_of_remove_table(dev);
> - clk_disable_unprepare(bus->clk);
> }
>
> /*
> @@ -326,8 +326,7 @@ static int exynos_bus_parent_parse_of(struct device_node *np,
> return ret;
> }
>
> -static int exynos_bus_parse_of(struct device_node *np,
> - struct exynos_bus *bus)
> +static int exynos_bus_parse_of(struct exynos_bus *bus)
> {
> struct device *dev = bus->dev;
> struct dev_pm_opp *opp;
> @@ -341,36 +340,35 @@ static int exynos_bus_parse_of(struct device_node *np,
> return PTR_ERR(bus->clk);
> }
>
> - ret = clk_prepare_enable(bus->clk);
> + /* Get the freq and voltage from OPP table to scale the bus freq */
> + ret = dev_pm_opp_of_add_table(dev);
> if (ret < 0) {
> - dev_err(dev, "failed to get enable clock\n");
> + dev_err(dev, "failed to get OPP table\n");
> return ret;
> }
>
> - /* Get the freq and voltage from OPP table to scale the bus freq */
> - ret = dev_pm_opp_of_add_table(dev);
> + ret = clk_prepare_enable(bus->clk);
> if (ret < 0) {
> - dev_err(dev, "failed to get OPP table\n");
> + dev_err(dev, "failed to enable clock\n");
> goto err_clk;
> }
> -
> rate = clk_get_rate(bus->clk);
>
> opp = devfreq_recommended_opp(dev, &rate, 0);
> if (IS_ERR(opp)) {
> dev_err(dev, "failed to find dev_pm_opp\n");
> ret = PTR_ERR(opp);
> - goto err_opp;
> + goto err;
> }
> bus->curr_freq = dev_pm_opp_get_freq(opp);
> dev_pm_opp_put(opp);
>
> return 0;
>
> -err_opp:
> - dev_pm_opp_of_remove_table(dev);
> -err_clk:
> +err:
> clk_disable_unprepare(bus->clk);
> +err_clk:
> + dev_pm_opp_of_remove_table(dev);
>
> return ret;
> }
> @@ -386,6 +384,7 @@ static int exynos_bus_probe(struct platform_device *pdev)
> struct exynos_bus *bus;
> int ret, max_state;
> unsigned long min_freq, max_freq;
> + bool passive = false;
>
> if (!np) {
> dev_err(dev, "failed to find devicetree node\n");
> @@ -399,27 +398,31 @@ static int exynos_bus_probe(struct platform_device *pdev)
> bus->dev = &pdev->dev;
> platform_set_drvdata(pdev, bus);
>
> - /* Parse the device-tree to get the resource information */
> - ret = exynos_bus_parse_of(np, bus);
> - if (ret < 0)
> - return ret;
> -
> profile = devm_kzalloc(dev, sizeof(*profile), GFP_KERNEL);
> - if (!profile) {
> - ret = -ENOMEM;
> - goto err;
> - }
> + if (!profile)
> + return -ENOMEM;
>
> node = of_parse_phandle(dev->of_node, "devfreq", 0);
> if (node) {
> of_node_put(node);
> - goto passive;
> + passive = true;
> } else {
> ret = exynos_bus_parent_parse_of(np, bus);
> + if (ret < 0)
> + return ret;
> }
>
> - if (ret < 0)
> - goto err;
> + /* 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 (passive)
> + goto passive;
>
> /* Initialize the struct profile and governor data for parent device */
> profile->polling_ms = 50;
> @@ -508,8 +511,11 @@ static int exynos_bus_probe(struct platform_device *pdev)
> return 0;
>
> err:
> - dev_pm_opp_of_remove_table(dev);
> clk_disable_unprepare(bus->clk);
> + if (!passive)
> + regulator_disable(bus->regulator);
> +
> + dev_pm_opp_of_remove_table(dev);
>
> return ret;
> }
>
Acked-by: Chanwoo Choi <cw00.choi@...sung.com>
--
Best Regards,
Chanwoo Choi
Samsung Electronics
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