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From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: linux-arm-msm@vger.kernel.org,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Vinod Koul <vinod.koul@linaro.org>,
	Linux PM <linux-pm@vger.kernel.org>
Subject: PSCI domains without OSI support
Date: Wed, 27 Jul 2022 12:09:27 +0300	[thread overview]
Message-ID: <CAA8EJpr2S-81+q-vjmk5i+T-JwaadkRpjCr_oGi7fMf7o3iH3A@mail.gmail.com> (raw)

Hi,

Lately I have been working on improving the msm8996 platform support.
Vendor kernel seems to support domain-like idle (see [1], [2]).
However when I tried changing upstream msm8996.dtsi to use PSCI
domains, I faced the firmware reporting NOT_SUPPORTED to an attempt to
enable OSI (thus rendering PSCI domains useless, as they are now
marked with ALWAYS_ON).

I noticed that vendor kernel makes a call to cpu_suspend() with
power_state following the original format (described in PSCI spec
5.4.2.1). What would be the best way to support this?
- Allow DTS forcing the PSCI power domains even if OSI enablement fails?
- Add a separate cpuidle driver?
- Just forget about it and use plain PSCI as we currently do?

Additional topic: for one of idle states the vendor kernel uses a
proprietary call into the hypervisor ([3]). Up to now we have ignored
this, as 8996 seems to be the only platform using it. I suppose that
adding it to cpuidle-psci.c would be frowned upon. Is this assumption
correct? Would it add another point for adding a separate cpuidle
driver?

[1] https://git.codelinaro.org/clo/la/kernel/msm-3.18/-/blob/LA.UM.6.6.c31-02700-89xx.0/arch/arm/boot/dts/qcom/msm8996-pm.dtsi#L32

[2] https://git.codelinaro.org/clo/la/kernel/msm-3.18/-/blob/LA.UM.6.6.c31-02700-89xx.0/drivers/cpuidle/lpm-levels.c#L927

[3] https://git.codelinaro.org/clo/la/kernel/msm-3.18/-/blob/LA.UM.6.6.c31-02700-89xx.0/drivers/cpuidle/lpm-levels.c#L944

-- 
With best wishes
Dmitry

             reply	other threads:[~2022-07-27  9:13 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-27  9:09 Dmitry Baryshkov [this message]
2022-07-27 11:14 ` PSCI domains without OSI support Sudeep Holla
2022-07-27 13:24   ` Dmitry Baryshkov
2022-07-27 13:39     ` Dmitry Baryshkov
2022-07-27 20:51       ` Dmitry Baryshkov
2022-08-05 13:47         ` Ulf Hansson
2022-07-28  8:40     ` Sudeep Holla
2022-07-28  9:15       ` Dmitry Baryshkov
2022-08-05 14:12       ` Ulf Hansson
2022-08-05 16:00         ` Sudeep Holla
2022-08-05 21:39           ` Dmitry Baryshkov
2022-08-12 11:32             ` Ulf Hansson

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