From: Mark Rutland <mark.rutland@arm.com>
To: Pramod Kumar <pramod.kumar@broadcom.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Suzuki K Poulose <Suzuki.Poulose@arm.com>,
Sudeep Holla <sudeep.holla@arm.com>,
Dave Martin <dave.martin@arm.com>, Rob Herring <robh@kernel.org>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Steve Capper <steve.capper@arm.com>,
BCM Kernel Feedback <bcm-kernel-feedback-list@broadcom.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC 1/1] arm64: Use PSCI calls for CPU stop when hotplug is supported
Date: Wed, 23 Jan 2019 16:56:07 +0000 [thread overview]
Message-ID: <20190123165607.GB55887@lakrids.cambridge.arm.com> (raw)
In-Reply-To: <1547790380-6276-1-git-send-email-pramod.kumar@broadcom.com>
On Fri, Jan 18, 2019 at 11:16:20AM +0530, Pramod Kumar wrote:
> If CPU hotplug is supported, ipi_cpu_stop should use PSCI cpudie
> call to stop the CPU. This call ensures L1/L2 cache flush,
> CPUs cache-cohenrecy setting w.r.to interconnect.
>
> Apart from this, this gives control to f/w to reduce power consumption
> by take appropriate decesion on power rails for plugging-out core.
>
> Signed-off-by: Pramod Kumar <pramod.kumar@broadcom.com>
> Reviewed-by: Ray Jui <ray.jui@broadcom.com>
> Reviewed-by: Scott Branden <scott.branden@broadcom.com>
> ---
> arch/arm64/kernel/smp.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index 1598d6f..360e52b 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -822,8 +822,13 @@ static void ipi_cpu_stop(unsigned int cpu)
> local_daif_mask();
> sdei_mask_local_cpu();
>
> +#ifdef CONFIG_HOTPLUG_CPU
> + if (cpu_ops[cpu]->cpu_die)
> + cpu_ops[cpu]->cpu_die(cpu);
> +#else
> while (1)
> cpu_relax();
> +#endif
If cpu_ops[cpu]->cpu_die is NULL, this change makes ipi_cpu_stop()
return, which is not correct.
Regardless, I don't think that there is sufficient rationale for this
change, especially given that your commit message describes
platform-specific assumptions which do not hold in general.
Thanks,
Mark.
prev parent reply other threads:[~2019-01-23 16:56 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-18 5:46 [PATCH RFC 1/1] arm64: Use PSCI calls for CPU stop when hotplug is supported Pramod Kumar
2019-01-18 11:32 ` Sudeep Holla
[not found] ` <CAJ+tv6+6yqT1xkmkY3x6SNQ83K+J6zqKZr7PV5A_ffvyEzceqg@mail.gmail.com>
[not found] ` <CAJ+tv6KqynSf5t_VwLqpdM4BF+wLWcJ0wPTD4nWqL4ej1Yih4g@mail.gmail.com>
2019-01-21 6:06 ` Pramod Kumar
2019-01-23 16:48 ` Mark Rutland
2019-01-23 17:05 ` Scott Branden
2019-01-23 17:21 ` Sudeep Holla
2019-01-23 17:33 ` Scott Branden
2019-01-23 17:33 ` Mark Rutland
2019-01-23 17:46 ` Scott Branden
2019-01-23 18:07 ` Sudeep Holla
2019-01-25 7:03 ` Pramod Kumar
2019-01-25 15:56 ` Robin Murphy
2019-01-25 16:52 ` Sudeep Holla
2019-01-21 11:22 ` Sudeep Holla
2019-01-23 4:51 ` Pramod Kumar
2019-01-23 16:27 ` Sudeep Holla
2019-01-23 16:56 ` Mark Rutland [this message]
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=20190123165607.GB55887@lakrids.cambridge.arm.com \
--to=mark.rutland@arm.com \
--cc=Suzuki.Poulose@arm.com \
--cc=bcm-kernel-feedback-list@broadcom.com \
--cc=catalin.marinas@arm.com \
--cc=dave.martin@arm.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=lorenzo.pieralisi@arm.com \
--cc=pramod.kumar@broadcom.com \
--cc=robh@kernel.org \
--cc=steve.capper@arm.com \
--cc=sudeep.holla@arm.com \
--cc=will.deacon@arm.com \
/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).