From: Sudeep Holla <sudeep.holla@arm.com>
To: Hanjun Guo <guohanjun@huawei.com>
Cc: 'Thanu Rangarajan' <Thanu.Rangarajan@arm.com>,
Sudeep Holla <sudeep.holla@arm.com>,
souvik.chakravarty@arm.com, John Garry <john.garry@huawei.com>,
Linuxarm <linuxarm@huawei.com>,
Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>,
Matteo Carlini <Matteo.Carlini@arm.com>,
Jonathan Cameron <jonathan.cameron@huawei.com>,
linux-arm-kernel@lists.infradead.org,
Charles Garcia-Tobin <Charles.Garcia-Tobin@arm.com>
Subject: Re: ACPI support for System Control and Management Interface (SCMI)
Date: Tue, 14 Apr 2020 11:54:24 +0100 [thread overview]
Message-ID: <20200414105424.GB17835@bogus> (raw)
In-Reply-To: <52a50069-7140-b9b4-31b4-8c99e8c0d991@huawei.com>
On Fri, Apr 10, 2020 at 10:26:41AM +0800, Hanjun Guo wrote:
> Hi Sudeep,
>
> We are working on the enablement of SCMI for Kunepeng920,
> which is a server chip using ACPI, but I didn't see the
> ACPI support in the mainline kernel for SCMI.
>
> Kunpeng920 and the upcomming Kunpeng930 have thermal
> sensors and other system management features which
> needs the SCMI for abstraction layer, do we have plan
> to support ACPI for SCMI?
>
Yes and No.
Yes, because the same SCMI compliant firmware needs to work with ACPI as
SCMI is designed so.
No, because we don't plan to add another SCMI layer below ACPI in the
kernel. ACPI specification was extended to support special PCC types
to support the same. IIUC things like sensors are supported using power
meter objects in ACPI and you must be able to use PCC opregion for it or
any custom mechanism to achieve that. However one need to add PCC opregion
handler in Linux. The main idea is you must use existing ACPI methods
and we don't plan to add anything special for SCMI.
SCMI Perf protocol is compatible with CPPC. We can discuss details once
you explore PCC opregion or any alternative you come up with. I am no
ACPI firmware expert and I reckon you may have other interesting ideas.
--
Regards,
Sudeep
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next prev parent reply other threads:[~2020-04-14 10:54 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-10 2:26 ACPI support for System Control and Management Interface (SCMI) Hanjun Guo
2020-04-14 2:55 ` Thanu Rangarajan
2020-04-14 10:54 ` Sudeep Holla [this message]
2020-04-14 12:08 ` Souvik Chakravarty
2020-04-18 2:16 ` Hanjun Guo
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