linux-kernel - Re: [PATCH v2 04/10] clk: qcom: Add support for PLLs with alpha mode

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Message-ID: <57BEB66C.2000602@codeaurora.org>
Date:   Thu, 25 Aug 2016 14:42:12 +0530
From:   Rajendra Nayak <rnayak@...eaurora.org>
To:     Stephen Boyd <sboyd@...eaurora.org>
CC:     mturquette@...libre.com, linux-clk@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        tdas@...eaurora.org
Subject: Re: [PATCH v2 04/10] clk: qcom: Add support for PLLs with alpha mode

On 08/24/2016 11:45 AM, Stephen Boyd wrote:
> On 08/11, Rajendra Nayak wrote:
>> Some PLLs can support an alpha mode, and a single alpha
>> register (instead of registers to program the M/N values),
>> the contents of which depend on the alpha mode selected.
>> (They are either treated as two's complement or M/N value)
> 
> That's just a sentence, so please drop the parentheses.

OK

> 
>> Add support for this in the clk PLL driver.
>>
> 
> I'm confused, don't we already have clk-alpha-pll.c to handle
> alpha type plls? What are we doing adding support to the "legacy"
> pll code?

Yes, this does look confusing now that I took a relook at it all.
I will redo this whole thing so it fits into the alpha PLL support that
we already have.

> 
>> Signed-off-by: Rajendra Nayak <rnayak@...eaurora.org>
>> ---
>>  drivers/clk/qcom/clk-pll.c | 8 ++++++--
>>  drivers/clk/qcom/clk-pll.h | 2 ++
>>  2 files changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/clk/qcom/clk-pll.c b/drivers/clk/qcom/clk-pll.c
>> index 5b940d6..08d2fa2 100644
>> --- a/drivers/clk/qcom/clk-pll.c
>> +++ b/drivers/clk/qcom/clk-pll.c
>> @@ -255,8 +255,12 @@ static void clk_pll_configure(struct clk_pll *pll, struct regmap *regmap,
>>  	u32 mask;
>>  
>>  	regmap_write(regmap, pll->l_reg, config->l);
>> -	regmap_write(regmap, pll->m_reg, config->m);
>> -	regmap_write(regmap, pll->n_reg, config->n);
>> +	if (pll->alpha_reg) {
> 
> This assumes that alpha_reg is not 0 offset from base, which
> seems like a bad assumption to make.

sure, I need to handle this in a better way

> 
>> +		regmap_write(regmap, pll->alpha_reg, config->alpha);
>> +	} else {
>> +		regmap_write(regmap, pll->m_reg, config->m);
>> +		regmap_write(regmap, pll->n_reg, config->n);
>> +	}
>>  
>>  	val = config->vco_val;
>>  	val |= config->pre_div_val;
>>
> 

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