Re: [PATCH 07/13] clk: qcom: clk-alpha-pll: Add support to skip PLL configuration

[Jagadeesh Kona <jagadeesh.kona@oss.qualcomm.com>]

On 4/23/2026 4:43 PM, Konrad Dybcio wrote:
> On 4/22/26 8:28 PM, Dmitry Baryshkov wrote:
>> On Mon, Apr 20, 2026 at 09:59:00PM +0530, Jagadeesh Kona wrote:
>>> Some PLLs are already configured as part of CRM(CESTA Resource
>>> manager) initialization. Add support to skip PLL reconfiguration
>>> for such PLLs that are already configured.
>>>
>>> Signed-off-by: Jagadeesh Kona <jagadeesh.kona@oss.qualcomm.com>
>>> ---
>>>  drivers/clk/qcom/clk-alpha-pll.c | 8 +++++++-
>>>  1 file changed, 7 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
>>> index 67fc97739d0d4c26aec0bac5d43d1b87d297bc6a..2f4ebf4d3884b92c981dbe0e67245704a88881ad 100644
>>> --- a/drivers/clk/qcom/clk-alpha-pll.c
>>> +++ b/drivers/clk/qcom/clk-alpha-pll.c
>>> @@ -2332,7 +2332,7 @@ EXPORT_SYMBOL_GPL(clk_alpha_pll_zonda_ops);
>>>  void clk_lucid_evo_pll_configure(struct clk_alpha_pll *pll, struct regmap *regmap,
>>>  				 const struct alpha_pll_config *config)
>>>  {
>>> -	u32 lval = config->l;
>>> +	u32 lval = config->l, regval;
>>>  
>>>  	/*
>>>  	 * If the bootloader left the PLL enabled it's likely that there are
>>> @@ -2343,6 +2343,12 @@ void clk_lucid_evo_pll_configure(struct clk_alpha_pll *pll, struct regmap *regma
>>>  		return;
>>>  	}
>>>  
>>> +	/* Return early if PLL is already configured */
>>> +	regmap_read(regmap, PLL_L_VAL(pll), &regval);
>>> +	regval &= LUCID_EVO_PLL_L_VAL_MASK;
>>> +	if (regval)
>>> +		return;
>>> +
>>
>> Why is it being applied only to Lucid EVO PLLs?
> 

Thanks Dmitry and Konrad for your reviews.

This is the function used to configure all Taycan PLLs, currently all the PLLs
configured during CESTA initialization belong to Taycan type only. I will recheck
if similar logic is required for any additional PLL types also.


> These clocks already have a an .is_enabled() callback, could that be
> treated as equivalent?
> 

We already have is_enabled check to avoid configuring PLL's that are already enabled.
There can be case where PLL is configured from bootloader but not enabled during bootup.
This check avoids re-configuring such PLLs that are already configured by bootloader but
not enabled.

Thanks,
Jagadeesh