linux-kernel - Re: [PATCH v2 11/11] clk: qcom: gpucc-msm8998: Allow fabia gpupll0 rate setting

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Message-ID: <a9593d00-3ab4-4833-0bf5-516cf432ba48@somainline.org>
Date:   Tue, 9 Feb 2021 14:18:15 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...ainline.org>
To:     Stephen Boyd <sboyd@...nel.org>, linux-arm-msm@...r.kernel.org
Cc:     konrad.dybcio@...ainline.org, marijn.suijten@...ainline.org,
        martin.botka@...ainline.org, phone-devel@...r.kernel.org,
        linux-kernel@...r.kernel.org, agross@...nel.org,
        bjorn.andersson@...aro.org, mturquette@...libre.com,
        robh+dt@...nel.org, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v2 11/11] clk: qcom: gpucc-msm8998: Allow fabia gpupll0
 rate setting

Il 08/02/21 19:24, Stephen Boyd ha scritto:
> Quoting AngeloGioacchino Del Regno (2021-01-14 14:10:59)
>> The GPU PLL0 is not a fixed PLL and the rate can be set on it:
>> this is necessary especially on boards which bootloader is setting
>> a very low rate on this PLL before booting Linux, which would be
>> unsuitable for postdividing to reach the maximum allowed Adreno GPU
>> frequency of 710MHz (or, actually, even 670MHz..) on this SoC.
>>
>> To allow setting rates on the GPU PLL0, also define VCO boundaries
>> and set the CLK_SET_RATE_PARENT flag to the GPU PLL0 postdivider.
>>
>> With this change, the Adreno GPU is now able to scale through all
>> the available frequencies.
> 
> BTW, you're probably undervolting your GPU and clocking it higher
> than it should be at the voltage from boot.
> 

Thanks for the consideration, but that's not the case, locally ;)

>>
>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...ainline.org>
>> ---
>>   drivers/clk/qcom/gpucc-msm8998.c | 10 +++++++++-
>>   1 file changed, 9 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/clk/qcom/gpucc-msm8998.c b/drivers/clk/qcom/gpucc-msm8998.c
>> index 1a518c4915b4..fedfffaf0a8d 100644
>> --- a/drivers/clk/qcom/gpucc-msm8998.c
>> +++ b/drivers/clk/qcom/gpucc-msm8998.c
>> @@ -50,6 +50,11 @@ static struct clk_branch gpucc_cxo_clk = {
>>          },
>>   };
>>   
>> +static struct pll_vco fabia_vco[] = {
> 
> Should be const.
> 

Ack!

>> +       { 249600000, 2000000000, 0 },
>> +       { 125000000, 1000000000, 1 },
>> +};
>> +
>>   static const struct clk_div_table post_div_table_fabia_even[] = {
>>          { 0x0, 1 },
>>          { 0x1, 2 },