linux-kernel - Re: [PATCH v6 2/4] media: venus: pm_helpers: use opp-table for the frequency

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Message-ID: <351a9654-ffa1-4727-b772-95d4ed113c81@quicinc.com>
Date: Thu, 2 Jan 2025 13:38:33 +0800
From: Renjiang Han <quic_renjiang@...cinc.com>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
        Stanimir Varbanov
	<stanimir.k.varbanov@...il.com>,
        Vikash Garodia <quic_vgarodia@...cinc.com>,
        Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
        Mauro Carvalho Chehab
	<mchehab@...nel.org>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski
	<krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Bjorn Andersson
	<andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>
CC: <linux-arm-msm@...r.kernel.org>, <linux-media@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 2/4] media: venus: pm_helpers: use opp-table for the
 frequency


On 12/23/2024 10:17 PM, Konrad Dybcio wrote:
> On 19.12.2024 6:41 AM, Renjiang Han wrote:
>> The frequency value in the opp-table in the device tree and the freq_tbl
>> in the driver are the same.
>>
>> Therefore, update pm_helpers.c to use the opp-table for frequency values
>> for the v4 core.
>> If getting data from the opp table fails, fall back to using the frequency
>> table.
>>
>> Signed-off-by: Renjiang Han<quic_renjiang@...cinc.com>
>> ---
>>   drivers/media/platform/qcom/venus/pm_helpers.c | 53 +++++++++++++++++++-------
>>   1 file changed, 39 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/media/platform/qcom/venus/pm_helpers.c b/drivers/media/platform/qcom/venus/pm_helpers.c
>> index 33a5a659c0ada0ca97eebb5522c5f349f95c49c7..b61c0ad152878870b7223efa274e137d3636433b 100644
>> --- a/drivers/media/platform/qcom/venus/pm_helpers.c
>> +++ b/drivers/media/platform/qcom/venus/pm_helpers.c
>> @@ -43,14 +43,20 @@ static int core_clks_enable(struct venus_core *core)
>>   	const struct venus_resources *res = core->res;
>>   	const struct freq_tbl *freq_tbl = core->res->freq_tbl;
>>   	unsigned int freq_tbl_size = core->res->freq_tbl_size;
>> +	struct device *dev = core->dev;
>> +	struct dev_pm_opp *opp;
>>   	unsigned long freq;
>>   	unsigned int i;
>>   	int ret;
>>   
>> -	if (!freq_tbl)
>> -		return -EINVAL;
>> -
>> -	freq = freq_tbl[freq_tbl_size - 1].freq;
>> +	opp = dev_pm_opp_find_freq_ceil(dev, &freq);
>> +	if (IS_ERR(opp)) {
>> +		if (!freq_tbl)
>> +			return -EINVAL;
>> +		freq = freq_tbl[freq_tbl_size - 1].freq;
>> +	} else {
>> +		dev_pm_opp_put(opp);
>> +	}
> I'm not super convinced how this could have ever worked without
> scaling voltage levels, by the way. Perhaps this will squash some
> random bugs :|
>
> Konrad
  Thanks for your comment.
  The default value of freq is 0, and then dev_pm_opp_find_freq_ceil is
  used to match freq to the maximum value in opp-table that is close to
  0. The frequency values in opp-table and freq_tbl are the same, and
  dev_pm_opp_find_freq_ceil is used to assign the minimum value in
  opp-table to freq. So the logic is the same as before. I'm not sure if
  I've answered your concern.

-- 
Best Regards,
Renjiang