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Subject[PATCH v2 08/17] PM / devfreq: tegra30: Move clk-notifier's registration to governor's start
Date
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 a2cae8348dce..8e1c56790ac3 100644
--- a/drivers/devfreq/tegra30-devfreq.c
+++ b/drivers/devfreq/tegra30-devfreq.c
@@ -574,6 +574,19 @@ 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]);

@@ -600,6 +613,8 @@ 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;
}

@@ -616,6 +631,8 @@ 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,
@@ -860,22 +877,14 @@ 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);
@@ -891,9 +900,6 @@ 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);

@@ -910,7 +916,6 @@ 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);
--
2.22.0
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