From: Bjorn Andersson <bjorn.andersson@linaro.org>
To: Danny Lin <danny@kdrag0n.dev>
Cc: Andy Gross <agross@kernel.org>, Rob Herring <robh+dt@kernel.org>,
linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] arm64: dts: qcom: sm8150: Add PSCI idle states
Date: Mon, 28 Dec 2020 12:02:06 -0600 [thread overview]
Message-ID: <X+odnnZYFW3qpubJ@builder.lan> (raw)
In-Reply-To: <e7776f3c-a517-4cf3-9265-92dc0ac09c88@www.fastmail.com>
On Tue 22 Dec 20:00 CST 2020, Danny Lin wrote:
> On Sun, Dec 20, 2020 at 7:48 PM, Bjorn Andersson wrote:
> > On Sun 20 Dec 16:29 PST 2020, Danny Lin wrote:
> >
> > > Like other Qualcomm SoCs, sm8150 exposes CPU and cluster idle states
> > > through PSCI. Define the idle states to save power when the CPU is not
> > > in active use.
> > >
> > > These idle states, latency, and residency values match the downstream
> > > 4.14 kernel from Qualcomm as of LA.UM.8.1.r1-15600-sm8150.0.
> > >
> > > It's worth noting that the CPU has an additional C3 power collapse idle
> > > state between WFI and rail power collapse (with PSCI mode 0x40000003),
> > > but it is not officially used in downstream kernels due to "thermal
> > > throttling issues."
> > >
> >
> > Thanks Danny for this series, very happy to see this kind of additions.
> > Just one small question about the cluster param below.
> >
> > > Signed-off-by: Danny Lin <danny@kdrag0n.dev>
> > > ---
> > > arch/arm64/boot/dts/qcom/sm8150.dtsi | 50 ++++++++++++++++++++++++++++
> > > 1 file changed, 50 insertions(+)
> > >
> > > diff --git a/arch/arm64/boot/dts/qcom/sm8150.dtsi b/arch/arm64/boot/dts/qcom/sm8150.dtsi
> > > index 75ed38ee5d88..edc1fe6d7f1b 100644
> > > --- a/arch/arm64/boot/dts/qcom/sm8150.dtsi
> > > +++ b/arch/arm64/boot/dts/qcom/sm8150.dtsi
> > > @@ -50,6 +50,8 @@ CPU0: cpu@0 {
> > > compatible = "qcom,kryo485";
> > > reg = <0x0 0x0>;
> > > enable-method = "psci";
> > > + cpu-idle-states = <&LITTLE_CPU_SLEEP_0
> > > + &CLUSTER_SLEEP_0>;
> > > next-level-cache = <&L2_0>;
> > > qcom,freq-domain = <&cpufreq_hw 0>;
> > > #cooling-cells = <2>;
> > > @@ -67,6 +69,8 @@ CPU1: cpu@100 {
> > > compatible = "qcom,kryo485";
> > > reg = <0x0 0x100>;
> > > enable-method = "psci";
> > > + cpu-idle-states = <&LITTLE_CPU_SLEEP_0
> > > + &CLUSTER_SLEEP_0>;
> > > next-level-cache = <&L2_100>;
> > > qcom,freq-domain = <&cpufreq_hw 0>;
> > > #cooling-cells = <2>;
> > > @@ -82,6 +86,8 @@ CPU2: cpu@200 {
> > > compatible = "qcom,kryo485";
> > > reg = <0x0 0x200>;
> > > enable-method = "psci";
> > > + cpu-idle-states = <&LITTLE_CPU_SLEEP_0
> > > + &CLUSTER_SLEEP_0>;
> > > next-level-cache = <&L2_200>;
> > > qcom,freq-domain = <&cpufreq_hw 0>;
> > > #cooling-cells = <2>;
> > > @@ -96,6 +102,8 @@ CPU3: cpu@300 {
> > > compatible = "qcom,kryo485";
> > > reg = <0x0 0x300>;
> > > enable-method = "psci";
> > > + cpu-idle-states = <&LITTLE_CPU_SLEEP_0
> > > + &CLUSTER_SLEEP_0>;
> > > next-level-cache = <&L2_300>;
> > > qcom,freq-domain = <&cpufreq_hw 0>;
> > > #cooling-cells = <2>;
> > > @@ -110,6 +118,8 @@ CPU4: cpu@400 {
> > > compatible = "qcom,kryo485";
> > > reg = <0x0 0x400>;
> > > enable-method = "psci";
> > > + cpu-idle-states = <&BIG_CPU_SLEEP_0
> > > + &CLUSTER_SLEEP_0>;
> > > next-level-cache = <&L2_400>;
> > > qcom,freq-domain = <&cpufreq_hw 1>;
> > > #cooling-cells = <2>;
> > > @@ -124,6 +134,8 @@ CPU5: cpu@500 {
> > > compatible = "qcom,kryo485";
> > > reg = <0x0 0x500>;
> > > enable-method = "psci";
> > > + cpu-idle-states = <&BIG_CPU_SLEEP_0
> > > + &CLUSTER_SLEEP_0>;
> > > next-level-cache = <&L2_500>;
> > > qcom,freq-domain = <&cpufreq_hw 1>;
> > > #cooling-cells = <2>;
> > > @@ -138,6 +150,8 @@ CPU6: cpu@600 {
> > > compatible = "qcom,kryo485";
> > > reg = <0x0 0x600>;
> > > enable-method = "psci";
> > > + cpu-idle-states = <&BIG_CPU_SLEEP_0
> > > + &CLUSTER_SLEEP_0>;
> > > next-level-cache = <&L2_600>;
> > > qcom,freq-domain = <&cpufreq_hw 1>;
> > > #cooling-cells = <2>;
> > > @@ -152,6 +166,8 @@ CPU7: cpu@700 {
> > > compatible = "qcom,kryo485";
> > > reg = <0x0 0x700>;
> > > enable-method = "psci";
> > > + cpu-idle-states = <&BIG_CPU_SLEEP_0
> > > + &CLUSTER_SLEEP_0>;
> > > next-level-cache = <&L2_700>;
> > > qcom,freq-domain = <&cpufreq_hw 2>;
> > > #cooling-cells = <2>;
> > > @@ -196,6 +212,40 @@ core7 {
> > > };
> > > };
> > > };
> > > +
> > > + idle-states {
> > > + entry-method = "psci";
> > > +
> > > + LITTLE_CPU_SLEEP_0: cpu-sleep-0-0 {
> > > + compatible = "arm,idle-state";
> > > + idle-state-name = "little-rail-power-collapse";
> > > + arm,psci-suspend-param = <0x40000004>;
> > > + entry-latency-us = <355>;
> > > + exit-latency-us = <909>;
> > > + min-residency-us = <3934>;
> > > + local-timer-stop;
> > > + };
> > > +
> > > + BIG_CPU_SLEEP_0: cpu-sleep-1-0 {
> > > + compatible = "arm,idle-state";
> > > + idle-state-name = "big-rail-power-collapse";
> > > + arm,psci-suspend-param = <0x40000004>;
> > > + entry-latency-us = <241>;
> > > + exit-latency-us = <1461>;
> > > + min-residency-us = <4488>;
> > > + local-timer-stop;
> > > + };
> > > +
> > > + CLUSTER_SLEEP_0: cluster-sleep-0 {
> > > + compatible = "arm,idle-state";
> > > + idle-state-name = "cluster-power-collapse";
> > > + arm,psci-suspend-param = <0x400000F4>;
> >
> > How come this is 0xf4?
> >
> > Isn't downstream saying that this should be either 0x1 << 4 or 0xc24 <<
> > 4, depending on how deep we want to go? Could we at least mention why
> > this is 0xf4?
>
> I'm not sure where 0x400000F4 originally came from. I noticed that
> sdm845 uses the same 0xc24 mode in downstream, but Qualcomm used
> 0x400000F4 in mainline.
>
> I did some testing on a downstream kernel and found that the real value
> it uses on sm8150 is 0x4100c244, but the idle state doesn't work at all
> if I use the same value on mainline. The logic appears to be the same in
> the downstream sdm845 kernel. Maybe it has to do with how downstream has
> "notify RPM" before attempting to enter the idle state?
>
> In downstream, the final PSCI value is calculated as the sum of:
>
> 1. (cluster-mode & cluster-mode-mask) << cluster-mode-shift = (0xc24 & 0xfff) << 4 = 0xc240
> 2. (is-reset << 30) = 0x40000000
> 3. (affinity level & 0x3) << 24 = 0x1000000
> 4. (cpu-mode) = 0x4
>
> so 0xc240 + 0x40000000 + 0x1000000 + 0x4 = 0x4100c244.
>
> It's also possible that the problem comes from the cluster idle state
> needing all CPUs in the cluster to be asleep (as far as I know), since
> it doesn't look like mainline handles that.
>
Thanks for the explanation. I believe we have the code in place to do
OSI sleep using the "psci domain cpuidle" driver, but I'm not entirely
sure about the details about it - perhaps it's just a matter of wiring
it all up(?).
Let's go with your current patches and then swing back to this once
we've figured out the remaining details.
Thanks,
Bjorn
> >
> > Regards,
> > Bjorn
> >
> > > + entry-latency-us = <3263>;
> > > + exit-latency-us = <6562>;
> > > + min-residency-us = <9987>;
> > > + local-timer-stop;
> > > + };
> > > + };
> > > };
> > >
> > > firmware {
> > > --
> > > 2.29.2
> > >
> >
next prev parent reply other threads:[~2020-12-28 18:02 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-21 0:29 [PATCH 0/3] CPU power management for SM8150 Danny Lin
2020-12-21 0:29 ` [PATCH 1/3] arm64: dts: qcom: sm8150: Define CPU topology Danny Lin
2020-12-21 0:29 ` [PATCH 2/3] arm64: dts: qcom: sm8150: Add PSCI idle states Danny Lin
2020-12-21 3:48 ` Bjorn Andersson
2020-12-23 2:00 ` Danny Lin
2020-12-28 18:02 ` Bjorn Andersson [this message]
2020-12-29 23:19 ` Danny Lin
2021-01-04 4:44 ` Bjorn Andersson
2020-12-21 0:29 ` [PATCH 3/3] arm64: dts: qcom: sm8150: Add CPU capacities and energy model Danny Lin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=X+odnnZYFW3qpubJ@builder.lan \
--to=bjorn.andersson@linaro.org \
--cc=agross@kernel.org \
--cc=danny@kdrag0n.dev \
--cc=devicetree@vger.kernel.org \
--cc=linux-arm-msm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=robh+dt@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).