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From: Sibi Sankar <sibis@codeaurora.org>
To: Sudeep Holla <sudeep.holla@arm.com>
Cc: bjorn.andersson@linaro.org, viresh.kumar@linaro.org,
	swboyd@chromium.org, agross@kernel.org, robh+dt@kernel.org,
	rjw@rjwysocki.net, linux-arm-msm@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-pm@vger.kernel.org, dianders@chromium.org,
	mka@chromium.org
Subject: Re: [PATCH 2/2] arm64: dts: qcom: sc7280: Add cpu OPP tables
Date: Tue, 04 May 2021 23:55:10 +0530	[thread overview]
Message-ID: <1fc9fb8d9a94909ff9b7b76d598bd266@codeaurora.org> (raw)
In-Reply-To: <20210504144215.svmrmmsy4jtoixzv@bogus>

Hey Sudeep,

Thanks for the review!

On 2021-05-04 20:12, Sudeep Holla wrote:
> On Fri, Apr 30, 2021 at 07:58:21PM +0530, Sibi Sankar wrote:
>> Add OPP tables required to scale DDR/L3 per freq-domain on SC7280 
>> SoCs.
>> 
>> Signed-off-by: Sibi Sankar <sibis@codeaurora.org>
>> ---
>>  arch/arm64/boot/dts/qcom/sc7280.dtsi | 135 
>> +++++++++++++++++++++++++++++++++++
>>  1 file changed, 135 insertions(+)
>> 
>> diff --git a/arch/arm64/boot/dts/qcom/sc7280.dtsi 
>> b/arch/arm64/boot/dts/qcom/sc7280.dtsi
>> index 0bb835aeae33..90220cecb368 100644
>> --- a/arch/arm64/boot/dts/qcom/sc7280.dtsi
>> +++ b/arch/arm64/boot/dts/qcom/sc7280.dtsi
> 
> 
> [...]
> 
>> @@ -248,6 +273,116 @@
>>  		};
>>  	};
>> 
>> +	cpu0_opp_table: cpu0_opp_table {
>> +		compatible = "operating-points-v2";
>> +		opp-shared;
>> +
>> +		cpu0_opp1: opp-300000000 {
>> +			opp-hz = /bits/ 64 <300000000>;
>> +			opp-peak-kBps = <800000 9600000>;
>> +		};
>> +
>> +		cpu0_opp2: opp-691200000 {
>> +			opp-hz = /bits/ 64 <691200000>;
>> +			opp-peak-kBps = <800000 17817600>;
>> +		};
>> +
>> +		cpu0_opp3: opp-806400000 {
>> +			opp-hz = /bits/ 64 <806400000>;
>> +			opp-peak-kBps = <800000 20889600>;
>> +		};
>> +
>> +		cpu0_opp4: opp-940800000 {
>> +			opp-hz = /bits/ 64 <940800000>;
>> +			opp-peak-kBps = <1804000 24576000>;
>> +		};
>> +
>> +		cpu0_opp5: opp-1152000000 {
>> +			opp-hz = /bits/ 64 <1152000000>;
>> +			opp-peak-kBps = <2188000 27033600>;
>> +		};
>> +
>> +		cpu0_opp6: opp-1324800000 {
>> +			opp-hz = /bits/ 64 <1324800000>;
>> +			opp-peak-kBps = <2188000 33792000>;
>> +		};
>> +
>> +		cpu0_opp7: opp-1516800000 {
>> +			opp-hz = /bits/ 64 <1516800000>;
>> +			opp-peak-kBps = <3072000 38092800>;
>> +		};
>> +
>> +		cpu0_opp8: opp-1651200000 {
>> +			opp-hz = /bits/ 64 <1651200000>;
>> +			opp-peak-kBps = <3072000 41779200>;
>> +		};
>> +
>> +		cpu0_opp9: opp-1804800000 {
>> +			opp-hz = /bits/ 64 <1804800000>;
>> +			opp-peak-kBps = <4068000 48537600>;
>> +		};
>> +
>> +		cpu0_opp10: opp-1958400000 {
>> +			opp-hz = /bits/ 64 <1958400000>;
>> +			opp-peak-kBps = <4068000 48537600>;
>> +		};
>> +	};
>> +
> 
> NACK, this breaks if there is a mismatch from what is read from the 
> hardware
> and what is presented in this table above. Either add it from the some
> bootloader or other boot code to this table reading from the 
> hardware/firmware
> or find a way to link them without this.
> 
> Sorry I had warned long back about this when such links were discussed 
> as
> part of interconnect binding.

Not sure why this warrants a NACK,
as this was consensus for mapping
cpu freq to DDR/L3 bandwidth votes.
(We use the same solution on SDM845
and SC7180). The opp tables are
optional and when specified puts in
votes for DDR/L3. In the future the
table can be safely dropped when more
useful devfreq governors are upstreamed.

cpufreq: qcom: Don't add frequencies without an OPP

I guess your main concern for breakage
is ^^ commit? The original design is
to list a super set of frequencies
supported by all variants of the SoC
along with the required DDR/L3 bandwidth
values. When we run into non-documented
frequency we just wouldn't put in bw
votes for it which should be fine since
the entire opp_table is optional. If
this is the reason for the NACK I can
try get it reverted with Matthias's ack.


-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project.

  reply	other threads:[~2021-05-04 18:25 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-30 14:28 [PATCH 0/2] DDR/L3 Scaling support on SC7280 SoCs Sibi Sankar
2021-04-30 14:28 ` [PATCH 1/2] cpufreq: blacklist SC7280 in cpufreq-dt-platdev Sibi Sankar
2021-05-03 16:20   ` Matthias Kaehlcke
2021-04-30 14:28 ` [PATCH 2/2] arm64: dts: qcom: sc7280: Add cpu OPP tables Sibi Sankar
2021-05-03 16:36   ` Matthias Kaehlcke
2021-05-04  7:05     ` Sibi Sankar
2021-05-04 14:42   ` Sudeep Holla
2021-05-04 18:25     ` Sibi Sankar [this message]
2021-05-04 19:16       ` Matthias Kaehlcke
2021-05-05  8:49       ` Sudeep Holla
2021-05-05 10:09         ` Sibi Sankar
2021-05-05 11:41           ` Sudeep Holla
2021-05-05 11:37         ` Viresh Kumar
2021-05-05 11:44           ` Sudeep Holla

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