linux-kernel - Re: [PATCH RFC 1/8] opp: core: implement dev_pm_opp_get

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Message-ID: <ff0ec93b-e2d0-4022-b8ae-8e4d9d1eac9f@linaro.org>
Date: Thu, 14 Nov 2024 10:23:08 +0100
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Viresh Kumar <viresh.kumar@...aro.org>
Cc: Akhil P Oommen <quic_akhilpo@...cinc.com>,
 Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
 Stephen Boyd <sboyd@...nel.org>, "Rafael J. Wysocki" <rafael@...nel.org>,
 Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
 Konrad Dybcio <konradybcio@...nel.org>,
 Abhinav Kumar <quic_abhinavk@...cinc.com>,
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
 Marijn Suijten <marijn.suijten@...ainline.org>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Bjorn Andersson <andersson@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Connor Abbott <cwabbott0@...il.com>,
 linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 freedreno@...ts.freedesktop.org, devicetree@...r.kernel.org
Subject: Re: [PATCH RFC 1/8] opp: core: implement dev_pm_opp_get_bandwidth

Hi,

On 14/11/2024 05:10, Viresh Kumar wrote:
> On 13-11-24, 16:48, Neil Armstrong wrote:
>> Add and implement the dev_pm_opp_get_bandwidth() to retrieve
>> the OPP's bandwidth in the same was as the dev_pm_opp_get_voltage()
> 
>                                    way
> 
>> helper.
>>
>> Retrieving bandwidth is required in the case of the Adreno GPU
>> where the GPU Management Unit can handle the Bandwidth scaling.
>>
>> The helper can get the peak or everage bandwidth for any of
> 
>                                   average

Aww, good catch, thanks

> 
>> the interconnect path.
>>
>> Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>
>> ---
>>   drivers/opp/core.c     | 25 +++++++++++++++++++++++++
>>   include/linux/pm_opp.h |  7 +++++++
>>   2 files changed, 32 insertions(+)
>>
>> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
>> index 494f8860220d97fc690ebab5ed3b7f5f04f22d73..19fb82033de26b74e9604c33b9781689df2fe80a 100644
>> --- a/drivers/opp/core.c
>> +++ b/drivers/opp/core.c
>> @@ -106,6 +106,31 @@ static bool assert_single_clk(struct opp_table *opp_table)
>>   	return !WARN_ON(opp_table->clk_count > 1);
>>   }
>>   
>> +/**
>> + * dev_pm_opp_get_bandwidth() - Gets the peak bandwidth corresponding to an opp
> 
> s/peak bandwidth/bandwidth/

Ack

> 
>> + * @opp:	opp for which voltage has to be returned for
>> + * @peak:	select peak or average bandwidth
>> + * @index:	bandwidth index
>> + *
>> + * Return: peak bandwidth in kBps, else return 0
> 
> s/peak bandwidth/bandwidth/

Ack

> 
>> + */
>> +unsigned long dev_pm_opp_get_bandwidth(struct dev_pm_opp *opp, bool peak, int index)
>> +{
>> +	if (IS_ERR_OR_NULL(opp)) {
>> +		pr_err("%s: Invalid parameters\n", __func__);
>> +		return 0;
>> +	}
>> +
>> +	if (index > opp->opp_table->path_count)
>> +		return 0;
>> +
>> +	if (!opp->bandwidth)
>> +		return 0;
>> +
>> +	return peak ? opp->bandwidth[index].peak : opp->bandwidth[index].avg;
>> +}
>> +EXPORT_SYMBOL_GPL(dev_pm_opp_get_bandwidth);
> 
> All other bandwidth APIs are named as _bw, maybe do same here too ?
> 

Sure, I wasn't sure about that, will switch to _bw.

Neil