From: Sudeep Holla <sudeep.holla@arm.com>
To: Maulik Shah <quic_mkshah@quicinc.com>
Cc: andersson@kernel.org, ulf.hansson@linaro.org,
dianders@chromium.org, Sudeep Holla <sudeep.holla@arm.com>,
swboyd@chromium.org, wingers@google.com,
linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-pm@vger.kernel.org, jwerner@chromium.org,
quic_lsrao@quicinc.com, quic_rjendra@quicinc.com
Subject: Re: [PATCH v2 1/2] cpuidle: psci: Move enabling OSI mode after power domains creation
Date: Thu, 30 Mar 2023 10:34:31 +0100 [thread overview]
Message-ID: <20230330093431.xn5wwiwqbne5owf7@bogus> (raw)
In-Reply-To: <20230330084250.32600-2-quic_mkshah@quicinc.com>
On Thu, Mar 30, 2023 at 02:12:49PM +0530, Maulik Shah wrote:
> A switch from OSI to PC mode is only possible if all CPUs other than the
> calling one are OFF, either through a call to CPU_OFF or not yet booted.
>
As per the spec, all cores are in one of the following states:
- Running
- OFF, either through a call to CPU_OFF or not yet booted
- Suspended, through a call to CPU_DEFAULT_SUSPEND
Better to provide full information.
> Currently OSI mode is enabled before power domains are created. In cases
> where CPUidle states are not using hierarchical CPU topology the bail out
> path tries to switch back to PC mode which gets denied by firmware since
> other CPUs are online at this point and creates inconsistent state as
> firmware is in OSI mode and Linux in PC mode.
>
OK what is the issue if the other cores are online ? As long as they are
running, it is allowed in the spec, so your statement is incorrect.
Is CPUidle enabled before setting the OSI mode. I see only that can cause
issue as we don't use CPU_DEFAULT_SUSPEND. If idle is not yet enabled, it
shouldn't be a problem.
--
Regards,
Sudeep
next prev parent reply other threads:[~2023-03-30 9:34 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-30 8:42 [PATCH v2 0/2] Use PSCI OS initiated mode for sc7280 Maulik Shah
2023-03-30 8:42 ` [PATCH v2 1/2] cpuidle: psci: Move enabling OSI mode after power domains creation Maulik Shah
2023-03-30 9:34 ` Sudeep Holla [this message]
2023-03-30 12:06 ` Ulf Hansson
2023-03-30 13:13 ` Sudeep Holla
2023-03-31 1:46 ` Wing Li
[not found] ` <CADut4F3UmMXCYHeE6sXfoJtgEp36Fv65Poe1Z0JKT0DETyaowQ@mail.gmail.com>
2023-03-31 14:27 ` Sudeep Holla
2023-03-30 12:19 ` Ulf Hansson
2023-03-30 8:42 ` [PATCH v2 2/2] arm64: dts: qcom: sc7280: Add power-domains for cpuidle states Maulik Shah
2023-03-30 12:21 ` Ulf Hansson
2023-03-30 9:38 ` [PATCH v2 0/2] Use PSCI OS initiated mode for sc7280 Sudeep Holla
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