[PATCH v4] clk: tegra: pll: Improve PLLM enable-state detection

[PATCH v4] clk: tegra: pll: Improve PLLM enable-state detection

[Dmitry Osipenko]

Power Management Controller (PMC) can override the PLLM clock settings,
including the enable-state. Although PMC could only act as a second level
gate, meaning that PLLM needs to be enabled by the Clock and Reset
Controller (CaR) anyways if we want it to be enabled. Hence, when PLLM is
overridden by PMC, it needs to be enabled by CaR and ungated by PMC in
order to be functional. Please note that this patch doesn't fix any known
problem, and thus, it's merely a minor improvement.

Link: https://lore.kernel.org/linux-arm-kernel/20191210120909.GA2703785@ulmo/T/
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---

Changelog:

v4: - Renamed pllm_pmc_clk_enabled() to pllm_clk_is_gated_by_pmc() as
      it was suggested by Jon Hunter in the review comment to v3.

v3: - Dropped unintended code change that was accidentally added to v2.

v2: - Added clarifying comment to the code.

    - Prettified the code.

 drivers/clk/tegra/clk-pll.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/clk/tegra/clk-pll.c b/drivers/clk/tegra/clk-pll.c
index b2d39a66f0fa..ff13b371e176 100644
--- a/drivers/clk/tegra/clk-pll.c
+++ b/drivers/clk/tegra/clk-pll.c
@@ -327,16 +327,26 @@ int tegra_pll_wait_for_lock(struct tegra_clk_pll *pll)
 	return clk_pll_wait_for_lock(pll);
 }
 
+static bool pllm_clk_is_gated_by_pmc(struct tegra_clk_pll *pll)
+{
+	u32 val = readl_relaxed(pll->pmc + PMC_PLLP_WB0_OVERRIDE);
+
+	return (val & PMC_PLLP_WB0_OVERRIDE_PLLM_OVERRIDE) &&
+	      !(val & PMC_PLLP_WB0_OVERRIDE_PLLM_ENABLE);
+}
+
 static int clk_pll_is_enabled(struct clk_hw *hw)
 {
 	struct tegra_clk_pll *pll = to_clk_pll(hw);
 	u32 val;
 
-	if (pll->params->flags & TEGRA_PLLM) {
-		val = readl_relaxed(pll->pmc + PMC_PLLP_WB0_OVERRIDE);
-		if (val & PMC_PLLP_WB0_OVERRIDE_PLLM_OVERRIDE)
-			return val & PMC_PLLP_WB0_OVERRIDE_PLLM_ENABLE ? 1 : 0;
-	}
+	/*
+	 * Power Management Controller (PMC) can override the PLLM clock
+	 * settings, including the enable-state. The PLLM is enabled when
+	 * PLLM's CaR state is ON and when PLLM isn't gated by PMC.
+	 */
+	if ((pll->params->flags & TEGRA_PLLM) && pllm_clk_is_gated_by_pmc(pll))
+		return 0;
 
 	val = pll_readl_base(pll);
 
-- 
2.26.0

Re: [PATCH v4] clk: tegra: pll: Improve PLLM enable-state detection

[Jon Hunter]

On 09/07/2020 18:20, Dmitry Osipenko wrote:
> Power Management Controller (PMC) can override the PLLM clock settings,
> including the enable-state. Although PMC could only act as a second level
> gate, meaning that PLLM needs to be enabled by the Clock and Reset
> Controller (CaR) anyways if we want it to be enabled. Hence, when PLLM is
> overridden by PMC, it needs to be enabled by CaR and ungated by PMC in
> order to be functional. Please note that this patch doesn't fix any known
> problem, and thus, it's merely a minor improvement.
> 
> Link: https://lore.kernel.org/linux-arm-kernel/20191210120909.GA2703785@ulmo/T/
> Signed-off-by: Dmitry Osipenko <digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
> 
> Changelog:
> 
> v4: - Renamed pllm_pmc_clk_enabled() to pllm_clk_is_gated_by_pmc() as
>       it was suggested by Jon Hunter in the review comment to v3.
> 
> v3: - Dropped unintended code change that was accidentally added to v2.
> 
> v2: - Added clarifying comment to the code.
> 
>     - Prettified the code.
> 
>  drivers/clk/tegra/clk-pll.c | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/clk/tegra/clk-pll.c b/drivers/clk/tegra/clk-pll.c
> index b2d39a66f0fa..ff13b371e176 100644
> --- a/drivers/clk/tegra/clk-pll.c
> +++ b/drivers/clk/tegra/clk-pll.c
> @@ -327,16 +327,26 @@ int tegra_pll_wait_for_lock(struct tegra_clk_pll *pll)
>  	return clk_pll_wait_for_lock(pll);
>  }
>  
> +static bool pllm_clk_is_gated_by_pmc(struct tegra_clk_pll *pll)
> +{
> +	u32 val = readl_relaxed(pll->pmc + PMC_PLLP_WB0_OVERRIDE);
> +
> +	return (val & PMC_PLLP_WB0_OVERRIDE_PLLM_OVERRIDE) &&
> +	      !(val & PMC_PLLP_WB0_OVERRIDE_PLLM_ENABLE);
> +}
> +
>  static int clk_pll_is_enabled(struct clk_hw *hw)
>  {
>  	struct tegra_clk_pll *pll = to_clk_pll(hw);
>  	u32 val;
>  
> -	if (pll->params->flags & TEGRA_PLLM) {
> -		val = readl_relaxed(pll->pmc + PMC_PLLP_WB0_OVERRIDE);
> -		if (val & PMC_PLLP_WB0_OVERRIDE_PLLM_OVERRIDE)
> -			return val & PMC_PLLP_WB0_OVERRIDE_PLLM_ENABLE ? 1 : 0;
> -	}
> +	/*
> +	 * Power Management Controller (PMC) can override the PLLM clock
> +	 * settings, including the enable-state. The PLLM is enabled when
> +	 * PLLM's CaR state is ON and when PLLM isn't gated by PMC.
> +	 */
> +	if ((pll->params->flags & TEGRA_PLLM) && pllm_clk_is_gated_by_pmc(pll))
> +		return 0;
>  
>  	val = pll_readl_base(pll);


Thanks! This looks good to me. However, I just want to do a bit of
testing on Tegra124 (hopefully this week).

Jon

-- 
nvpublic

Re: [PATCH v4] clk: tegra: pll: Improve PLLM enable-state detection

[Dmitry Osipenko]

14.07.2020 11:20, Jon Hunter пишет:
> 
> On 09/07/2020 18:20, Dmitry Osipenko wrote:
>> Power Management Controller (PMC) can override the PLLM clock settings,
>> including the enable-state. Although PMC could only act as a second level
>> gate, meaning that PLLM needs to be enabled by the Clock and Reset
>> Controller (CaR) anyways if we want it to be enabled. Hence, when PLLM is
>> overridden by PMC, it needs to be enabled by CaR and ungated by PMC in
>> order to be functional. Please note that this patch doesn't fix any known
>> problem, and thus, it's merely a minor improvement.
>>
>> Link: https://lore.kernel.org/linux-arm-kernel/20191210120909.GA2703785@ulmo/T/
>> Signed-off-by: Dmitry Osipenko <digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> ---
>>
>> Changelog:
>>
>> v4: - Renamed pllm_pmc_clk_enabled() to pllm_clk_is_gated_by_pmc() as
>>       it was suggested by Jon Hunter in the review comment to v3.
>>
>> v3: - Dropped unintended code change that was accidentally added to v2.
>>
>> v2: - Added clarifying comment to the code.
>>
>>     - Prettified the code.
>>
>>  drivers/clk/tegra/clk-pll.c | 20 +++++++++++++++-----
>>  1 file changed, 15 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/clk/tegra/clk-pll.c b/drivers/clk/tegra/clk-pll.c
>> index b2d39a66f0fa..ff13b371e176 100644
>> --- a/drivers/clk/tegra/clk-pll.c
>> +++ b/drivers/clk/tegra/clk-pll.c
>> @@ -327,16 +327,26 @@ int tegra_pll_wait_for_lock(struct tegra_clk_pll *pll)
>>  	return clk_pll_wait_for_lock(pll);
>>  }
>>  
>> +static bool pllm_clk_is_gated_by_pmc(struct tegra_clk_pll *pll)
>> +{
>> +	u32 val = readl_relaxed(pll->pmc + PMC_PLLP_WB0_OVERRIDE);
>> +
>> +	return (val & PMC_PLLP_WB0_OVERRIDE_PLLM_OVERRIDE) &&
>> +	      !(val & PMC_PLLP_WB0_OVERRIDE_PLLM_ENABLE);
>> +}
>> +
>>  static int clk_pll_is_enabled(struct clk_hw *hw)
>>  {
>>  	struct tegra_clk_pll *pll = to_clk_pll(hw);
>>  	u32 val;
>>  
>> -	if (pll->params->flags & TEGRA_PLLM) {
>> -		val = readl_relaxed(pll->pmc + PMC_PLLP_WB0_OVERRIDE);
>> -		if (val & PMC_PLLP_WB0_OVERRIDE_PLLM_OVERRIDE)
>> -			return val & PMC_PLLP_WB0_OVERRIDE_PLLM_ENABLE ? 1 : 0;
>> -	}
>> +	/*
>> +	 * Power Management Controller (PMC) can override the PLLM clock
>> +	 * settings, including the enable-state. The PLLM is enabled when
>> +	 * PLLM's CaR state is ON and when PLLM isn't gated by PMC.
>> +	 */
>> +	if ((pll->params->flags & TEGRA_PLLM) && pllm_clk_is_gated_by_pmc(pll))
>> +		return 0;
>>  
>>  	val = pll_readl_base(pll);
> 
> 
> Thanks! This looks good to me. However, I just want to do a bit of
> testing on Tegra124 (hopefully this week).

Okay, thank you :)

Re: [PATCH v4] clk: tegra: pll: Improve PLLM enable-state detection

[Jon Hunter]

On 09/07/2020 18:20, Dmitry Osipenko wrote:
> Power Management Controller (PMC) can override the PLLM clock settings,
> including the enable-state. Although PMC could only act as a second level
> gate, meaning that PLLM needs to be enabled by the Clock and Reset
> Controller (CaR) anyways if we want it to be enabled. Hence, when PLLM is
> overridden by PMC, it needs to be enabled by CaR and ungated by PMC in
> order to be functional. Please note that this patch doesn't fix any known
> problem, and thus, it's merely a minor improvement.
> 
> Link: https://lore.kernel.org/linux-arm-kernel/20191210120909.GA2703785@ulmo/T/
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
> 
> Changelog:
> 
> v4: - Renamed pllm_pmc_clk_enabled() to pllm_clk_is_gated_by_pmc() as
>       it was suggested by Jon Hunter in the review comment to v3.
> 
> v3: - Dropped unintended code change that was accidentally added to v2.
> 
> v2: - Added clarifying comment to the code.
> 
>     - Prettified the code.
> 
>  drivers/clk/tegra/clk-pll.c | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/clk/tegra/clk-pll.c b/drivers/clk/tegra/clk-pll.c
> index b2d39a66f0fa..ff13b371e176 100644
> --- a/drivers/clk/tegra/clk-pll.c
> +++ b/drivers/clk/tegra/clk-pll.c
> @@ -327,16 +327,26 @@ int tegra_pll_wait_for_lock(struct tegra_clk_pll *pll)
>  	return clk_pll_wait_for_lock(pll);
>  }
>  
> +static bool pllm_clk_is_gated_by_pmc(struct tegra_clk_pll *pll)
> +{
> +	u32 val = readl_relaxed(pll->pmc + PMC_PLLP_WB0_OVERRIDE);
> +
> +	return (val & PMC_PLLP_WB0_OVERRIDE_PLLM_OVERRIDE) &&
> +	      !(val & PMC_PLLP_WB0_OVERRIDE_PLLM_ENABLE);
> +}
> +
>  static int clk_pll_is_enabled(struct clk_hw *hw)
>  {
>  	struct tegra_clk_pll *pll = to_clk_pll(hw);
>  	u32 val;
>  
> -	if (pll->params->flags & TEGRA_PLLM) {
> -		val = readl_relaxed(pll->pmc + PMC_PLLP_WB0_OVERRIDE);
> -		if (val & PMC_PLLP_WB0_OVERRIDE_PLLM_OVERRIDE)
> -			return val & PMC_PLLP_WB0_OVERRIDE_PLLM_ENABLE ? 1 : 0;
> -	}
> +	/*
> +	 * Power Management Controller (PMC) can override the PLLM clock
> +	 * settings, including the enable-state. The PLLM is enabled when
> +	 * PLLM's CaR state is ON and when PLLM isn't gated by PMC.
> +	 */
> +	if ((pll->params->flags & TEGRA_PLLM) && pllm_clk_is_gated_by_pmc(pll))
> +		return 0;
>  
>  	val = pll_readl_base(pll);
>  
> 

I have tested this on Jetson TK1 using u-boot to verify the behaviour
and it does indeed work as described here. I have also ran it through
the automated testing we have for Tegra and see no immediate issue.
Therefore ...

Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>

Thanks!
Jon

-- 
nvpublic

Re: [PATCH v4] clk: tegra: pll: Improve PLLM enable-state detection

[Dmitry Osipenko]

17.07.2020 19:55, Jon Hunter пишет:
...
> I have tested this on Jetson TK1 using u-boot to verify the behaviour
> and it does indeed work as described here. I have also ran it through
> the automated testing we have for Tegra and see no immediate issue.
> Therefore ...
> 
> Reviewed-by: Jon Hunter <jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> Tested-by: Jon Hunter <jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> 
> Thanks!
> Jon

Awesome, thank you!

Re: [PATCH v4] clk: tegra: pll: Improve PLLM enable-state detection

[Stephen Boyd]

Quoting Dmitry Osipenko (2020-07-09 10:20:57)
> Power Management Controller (PMC) can override the PLLM clock settings,
> including the enable-state. Although PMC could only act as a second level
> gate, meaning that PLLM needs to be enabled by the Clock and Reset
> Controller (CaR) anyways if we want it to be enabled. Hence, when PLLM is
> overridden by PMC, it needs to be enabled by CaR and ungated by PMC in
> order to be functional. Please note that this patch doesn't fix any known
> problem, and thus, it's merely a minor improvement.
> 
> Link: https://lore.kernel.org/linux-arm-kernel/20191210120909.GA2703785@ulmo/T/
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---

Applied to clk-next