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SubjectRe: [PATCH v8 11/21] clk: tegra: clk-dfll: Add suspend and resume support
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On 8/9/19 5:23 AM, Dmitry Osipenko wrote:
> 09.08.2019 2:46, Sowjanya Komatineni пишет:
>> This patch implements DFLL suspend and resume operation.
>>
>> During system suspend entry, CPU clock will switch CPU to safe
>> clock source of PLLP and disables DFLL clock output.
>>
>> DFLL driver suspend confirms DFLL disable state and errors out on
>> being active.
>>
>> DFLL is re-initialized during the DFLL driver resume as it goes
>> through complete reset during suspend entry.
>>
>> Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
>> ---
>> drivers/clk/tegra/clk-dfll.c | 56 ++++++++++++++++++++++++++++++
>> drivers/clk/tegra/clk-dfll.h | 2 ++
>> drivers/clk/tegra/clk-tegra124-dfll-fcpu.c | 1 +
>> 3 files changed, 59 insertions(+)
>>
>> diff --git a/drivers/clk/tegra/clk-dfll.c b/drivers/clk/tegra/clk-dfll.c
>> index f8688c2ddf1a..eb298a5d7be9 100644
>> --- a/drivers/clk/tegra/clk-dfll.c
>> +++ b/drivers/clk/tegra/clk-dfll.c
>> @@ -1487,6 +1487,7 @@ static int dfll_init(struct tegra_dfll *td)
>> td->last_unrounded_rate = 0;
>>
>> pm_runtime_enable(td->dev);
>> + pm_runtime_irq_safe(td->dev);
>> pm_runtime_get_sync(td->dev);
>>
>> dfll_set_mode(td, DFLL_DISABLED);
>> @@ -1513,6 +1514,61 @@ static int dfll_init(struct tegra_dfll *td)
>> return ret;
>> }
>>
>> +/**
>> + * tegra_dfll_suspend - check DFLL is disabled
>> + * @dev: DFLL device *
>> + *
>> + * DFLL clock should be disabled by the CPUFreq driver. So, make
>> + * sure it is disabled and disable all clocks needed by the DFLL.
>> + */
>> +int tegra_dfll_suspend(struct device *dev)
>> +{
>> + struct tegra_dfll *td = dev_get_drvdata(dev);
>> +
>> + if (dfll_is_running(td)) {
>> + dev_err(td->dev, "dfll is enabled while shouldn't be\n");
>> + return -EBUSY;
>> + }
>> +
>> + reset_control_assert(td->dvco_rst);
>> +
>> + return 0;
>> +}
>> +EXPORT_SYMBOL(tegra_dfll_suspend);
>> +
>> +/**
>> + * tegra_dfll_resume - reinitialize DFLL on resume
>> + * @dev: DFLL instance
>> + *
>> + * DFLL is disabled and reset during suspend and resume.
>> + * So, reinitialize the DFLL IP block back for use.
>> + * DFLL clock is enabled later in closed loop mode by CPUFreq
>> + * driver before switching its clock source to DFLL output.
>> + */
>> +int tegra_dfll_resume(struct device *dev)
>> +{
>> + struct tegra_dfll *td = dev_get_drvdata(dev);
>> +
>> + reset_control_deassert(td->dvco_rst);
> This doesn't look right because I assume that DFLL resetting is
> synchronous and thus clk should be enabled in order for reset to
> propagate inside hardware.
>
>> + pm_runtime_get_sync(td->dev);
> Hence it will be better to remove the above reset_control_deassert() and
> add here:
>
> reset_control_reset(td->dvco_rst);

By the time dfll resume happens, dfll controller clock will already be
enabled.

so doing reset de-assert before pm_runtime seems ok.

>> + dfll_set_mode(td, DFLL_DISABLED);
>> + dfll_set_default_params(td);
>> +
>> + if (td->soc->init_clock_trimmers)
>> + td->soc->init_clock_trimmers();
>> +
>> + dfll_set_open_loop_config(td);
>> +
>> + dfll_init_out_if(td);
>> +
>> + pm_runtime_put_sync(td->dev);
>> +
>> + return 0;
>> +}
>> +EXPORT_SYMBOL(tegra_dfll_resume);
>> +
>> /*
>> * DT data fetch
>> */
>> diff --git a/drivers/clk/tegra/clk-dfll.h b/drivers/clk/tegra/clk-dfll.h
>> index 1b14ebe7268b..fb209eb5f365 100644
>> --- a/drivers/clk/tegra/clk-dfll.h
>> +++ b/drivers/clk/tegra/clk-dfll.h
>> @@ -42,5 +42,7 @@ int tegra_dfll_register(struct platform_device *pdev,
>> struct tegra_dfll_soc_data *tegra_dfll_unregister(struct platform_device *pdev);
>> int tegra_dfll_runtime_suspend(struct device *dev);
>> int tegra_dfll_runtime_resume(struct device *dev);
>> +int tegra_dfll_suspend(struct device *dev);
>> +int tegra_dfll_resume(struct device *dev);
>>
>> #endif /* __DRIVERS_CLK_TEGRA_CLK_DFLL_H */
>> diff --git a/drivers/clk/tegra/clk-tegra124-dfll-fcpu.c b/drivers/clk/tegra/clk-tegra124-dfll-fcpu.c
>> index e84b6d52cbbd..2ac2679d696d 100644
>> --- a/drivers/clk/tegra/clk-tegra124-dfll-fcpu.c
>> +++ b/drivers/clk/tegra/clk-tegra124-dfll-fcpu.c
>> @@ -631,6 +631,7 @@ static int tegra124_dfll_fcpu_remove(struct platform_device *pdev)
>> static const struct dev_pm_ops tegra124_dfll_pm_ops = {
>> SET_RUNTIME_PM_OPS(tegra_dfll_runtime_suspend,
>> tegra_dfll_runtime_resume, NULL)
>> + SET_SYSTEM_SLEEP_PM_OPS(tegra_dfll_suspend, tegra_dfll_resume)
>> };
>>
>> static struct platform_driver tegra124_dfll_fcpu_driver = {
>>

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