Re: [PATCH v4 08/24] PM / devfreq: tegra30: Move clk-notifier's registration to governor's start

Chanwoo Choi
2019-07-16T12:08:47Z

Hi Dmitiry,

On 19. 7. 8. 오전 7:32, Dmitry Osipenko wrote:
> There is no point in receiving of the notifications while governor is
> stopped, let's keep them disabled like we do for the CPU freq-change
> notifications. This also fixes a potential use-after-free bug if
> notification happens after device's removal.
>
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
> drivers/devfreq/tegra30-devfreq.c | 33 ++++++++++++++++++-------------
> 1 file changed, 19 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
> index 48a799fa5f63..d5d04c25023b 100644
> --- a/drivers/devfreq/tegra30-devfreq.c
> +++ b/drivers/devfreq/tegra30-devfreq.c
> @@ -576,6 +576,19 @@ static int tegra_actmon_start(struct tegra_devfreq *tegra)
> actmon_writel(tegra, ACTMON_SAMPLING_PERIOD - 1,
> ACTMON_GLB_PERIOD_CTRL);
>
> + /*
> + * CLK notifications are needed in order to reconfigure the upper
> + * consecutive watermark in accordance to the actual clock rate
> + * to avoid unnecessary upper interrupts.
> + */
> + err = clk_notifier_register(tegra->emc_clock,
> + &tegra->clk_rate_change_nb);
> + if (err) {
> + dev_err(tegra->devfreq->dev.parent,
> + "Failed to register rate change notifier\n");
> + return err;
> + }
> +
> for (i = 0; i < ARRAY_SIZE(tegra->devices); i++)
> tegra_actmon_configure_device(tegra, &tegra->devices[i]);
>
> @@ -602,6 +615,8 @@ static int tegra_actmon_start(struct tegra_devfreq *tegra)
> for (i = 0; i < ARRAY_SIZE(tegra->devices); i++)
> tegra_actmon_stop_device(&tegra->devices[i]);
>
> + clk_notifier_unregister(tegra->emc_clock, &tegra->clk_rate_change_nb);
> +
> return err;
> }
>
> @@ -618,6 +633,8 @@ static void tegra_actmon_stop(struct tegra_devfreq *tegra)
>
> for (i = 0; i < ARRAY_SIZE(tegra->devices); i++)
> tegra_actmon_stop_device(&tegra->devices[i]);
> +
> + clk_notifier_unregister(tegra->emc_clock, &tegra->clk_rate_change_nb);
> }
>
> static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
> @@ -862,22 +879,14 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
>
> platform_set_drvdata(pdev, tegra);
>
> + tegra->clk_rate_change_nb.notifier_call = tegra_actmon_clk_notify_cb;
> tegra->cpu_rate_change_nb.notifier_call = tegra_actmon_cpu_notify_cb;
> INIT_WORK(&tegra->update_work, tegra_actmon_delayed_update);
>
> - tegra->clk_rate_change_nb.notifier_call = tegra_actmon_clk_notify_cb;
> - err = clk_notifier_register(tegra->emc_clock,
> - &tegra->clk_rate_change_nb);
> - if (err) {
> - dev_err(&pdev->dev,
> - "Failed to register rate change notifier\n");
> - goto remove_opps;
> - }
> -
> err = devfreq_add_governor(&tegra_devfreq_governor);
> if (err) {
> dev_err(&pdev->dev, "Failed to add governor: %d\n", err);
> - goto unreg_notifier;
> + goto remove_opps;
> }
>
> tegra_devfreq_profile.initial_freq = clk_get_rate(tegra->emc_clock);
> @@ -893,9 +902,6 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
> remove_governor:
> devfreq_remove_governor(&tegra_devfreq_governor);
>
> -unreg_notifier:
> - clk_notifier_unregister(tegra->emc_clock, &tegra->clk_rate_change_nb);
> -
> remove_opps:
> dev_pm_opp_remove_all_dynamic(&pdev->dev);
>
> @@ -912,7 +918,6 @@ static int tegra_devfreq_remove(struct platform_device *pdev)
> devfreq_remove_device(tegra->devfreq);
> devfreq_remove_governor(&tegra_devfreq_governor);
>
> - clk_notifier_unregister(tegra->emc_clock, &tegra->clk_rate_change_nb);
> dev_pm_opp_remove_all_dynamic(&pdev->dev);
>
> reset_control_reset(tegra->reset);
>

Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>

--
Best Regards,
Chanwoo Choi
Samsung Electronics