Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Received-SPF: Pass (protection.outlook.com: domain of nvidia.com designates
 216.228.112.34 as permitted sender) receiver=protection.outlook.com;
 client-ip=216.228.112.34; helo=mail.nvidia.com;
Subject: Re: [RFC PATCH 0/4] Support for passing runtime state idle time to
 TF-A
To:     <sudeep.holla@arm.com>, <souvik.chakravarty@arm.com>,
        <thierry.reding@gmail.com>, <mark.rutland@arm.com>,
        <lorenzo.pieralisi@arm.com>, <daniel.lezcano@linaro.org>,
        <robh+dt@kernel.org>
CC:     <jonathanh@nvidia.com>, <ksitaraman@nvidia.com>,
        <sanjayc@nvidia.com>, <linux-arm-kernel@lists.infradead.org>,
        <linux-tegra@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-pm@vger.kernel.org>, <devicetree@vger.kernel.org>
References: <1619123448-10138-1-git-send-email-skomatineni@nvidia.com>
From:   Sowjanya Komatineni <skomatineni@nvidia.com>
Message-ID: <82b57776-9002-0dc8-aa0e-f1057ce3beef@nvidia.com>
Date:   Thu, 22 Apr 2021 18:03:27 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.10.0
MIME-Version: 1.0
In-Reply-To: <1619123448-10138-1-git-send-email-skomatineni@nvidia.com>
Content-Type: text/plain; charset="utf-8"; format=flowed
Content-Transfer-Encoding: 7bit
Content-Language: en-US
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Apr 2021 01:03:30.8722
 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: 88da28b7-2799-4c8b-15e0-08d905f39c76
X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.112.34];Helo=[mail.nvidia.com]
X-MS-Exchange-CrossTenant-AuthSource: CO1NAM11FT008.eop-nam11.prod.protection.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Anonymous
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR12MB3643
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

kernel test robot reported below errors for patch-2 of this series. Will 
fix in next version to use div_u64() for nsec to usec conversion along 
with the other feedback I may be receiving.

drivers/cpuidle/governors/menu.c:398: undefined reference to `__udivdi3'
ld: drivers/cpuidle/governors/menu.c:398: undefined reference to `__udivdi3'
ld: drivers/cpuidle/governors/menu.c:398: undefined reference to `__udivdi3'
ld: drivers/cpuidle/governors/menu.c:398: undefined reference to `__udivdi3'

Thanks

Sowjanya

On 4/22/21 1:30 PM, Sowjanya Komatineni wrote:
> Tegra194 and Tegra186 platforms use separate MCE firmware for CPUs which is
> in charge of deciding on state transition based on target state, state idle
> time, and some other Tegra CPU core cluster states information.
>
> Current PSCI specification don't have function defined for passing runtime
> state idle time predicted by governor (based on next events and state target
> residency) to ARM trusted firmware.
>
> With the support of adding new PSCI function to allow passing runtime state
> idle time from kernel to ARM trusted firmware, Tegra194 platforms can use
> generic psci cpuidle driver rather than having Tegra specific cpuidle driver.
>
> During Tegra specific cpuidle driver V1 review, Sudeep Holla from ARM also
> suggested to use generic cpuidle driver by generalizing the need of runtime
> state idle time.
>
> So had internal discussion between ARM and NVIDIA on adding new PSCI function
> to allow passing runtime state idle time from kernel to TF-A through PSCI and
> once this implementation is accepted by upstream, ARM will look into further
> to update PSCI specification for this new PSCI function.
>
> So sending these patches as RFC as new PSCI function added in this series is
> not part of PSCI specification and once this implementation is accepted by ARM
> and upstream community, ARM can help to take this forward to add to PSCI
> specification.
>
> To keep the backward compatibility we can't update CPU_SUSPEND function to pass
> state idle time argument. So added seperate function for passing state idle time
> and serializing this with cpu suspend state enter.
>
> Once this approach is agreed, we can either use this way of separate PSCI
> function for passing state idle time or with PSCI specification update we can
> use same CPU_SUSPEND function with extra argument for state idle time which can
> be decided later for final patches based on discussion with ARM.
>
>
> Sowjanya Komatineni (4):
>    firmware/psci: add support for PSCI function SET_STATE_IDLE_TIME
>    cpuidle: menu: add idle_time to cpuidle_state
>    cpuidle: psci: pass state idle time before state enter callback
>    arm64: dts: tegra194: Add CPU idle states
>
>   arch/arm64/boot/dts/nvidia/tegra194.dtsi | 19 +++++++++++++++++++
>   drivers/cpuidle/cpuidle-psci.c           | 11 +++++++++++
>   drivers/cpuidle/governors/menu.c         |  7 ++++++-
>   drivers/firmware/psci/psci.c             |  9 +++++++++
>   include/linux/cpuidle.h                  |  1 +
>   include/linux/psci.h                     |  1 +
>   include/uapi/linux/psci.h                |  2 ++
>   7 files changed, 49 insertions(+), 1 deletion(-)
>