Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <26c77388-83cc-291c-4205-e1f6fc071875@amd.com>
Date:   Mon, 19 Dec 2022 16:37:40 -0600
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101
 Thunderbird/102.6.0
Subject: Re: [PATCH v8 02/13] Documentation: amd-pstate: add EPP profiles
 introduction
Content-Language: en-US
To:     Perry Yuan <perry.yuan@amd.com>, rafael.j.wysocki@intel.com,
        ray.huang@amd.com, viresh.kumar@linaro.org
Cc:     Deepak.Sharma@amd.com, Nathan.Fontenot@amd.com,
        Alexander.Deucher@amd.com, Shimmer.Huang@amd.com,
        Xiaojian.Du@amd.com, Li.Meng@amd.com, wyes.karny@amd.com,
        linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20221219064042.661122-1-perry.yuan@amd.com>
 <20221219064042.661122-3-perry.yuan@amd.com>
From:   "Limonciello, Mario" <mario.limonciello@amd.com>
In-Reply-To: <20221219064042.661122-3-perry.yuan@amd.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?MUNWTjlQMENqMnhHTjV1VGhiR2gzaGxaR1hkbzgxQ093Q0paS0NpM3k5bDQx?=
 =?utf-8?B?QWxSU0RxOVY4RHo5eitqdDZRUXFPazhWZlRvNGx0QUljakExMm0rSFZxYmFj?=
 =?utf-8?B?MWtwTTMyRVhjOVIvaGJ5bjdvSysrdmtsN0lJaVZaNFBtYkpRM3VJQ29UOGhY?=
 =?utf-8?B?VmRXQ0oxSHp2b3VnOTNMWnljS0g4R1lMQmM0anJyRHRmZXVRMm5oUnNZL1k2?=
 =?utf-8?B?MFJFVXNXdldENGtZL1hneUI4QU9vUi9wRm81Rko1eGltVnNjNk50ZU5mcndP?=
 =?utf-8?B?UFUzSmdFT2YxeXBVYnpxY0dxQU9PZGFCRzVvcERNUTdxdDk5RWRSL1htd2tH?=
 =?utf-8?B?L3Q1UjJFQ3VyVVo5cWdjWkJMRk16eGJUUkJzRDU4M0dXVEliUzBLRXI5ZDcz?=
 =?utf-8?B?d3J5eFB5bHp4N3lOKzNsaGZCVWwrdlo2QlJnSktlek1ZeUJVL0FEcHE5SHBp?=
 =?utf-8?B?SnpuMWpvTmd3a0tkYm9HbHdWaDdZSW5MM1V2NjJpaW1sRTZVSkhqZnBLMUxF?=
 =?utf-8?B?Q2tsZ3FTU21Delp0Qit2dGxpY2JSN20zSWFkbmpyV292djA0bCtGM1NnWUps?=
 =?utf-8?B?ZzE1UFVsTjlSSDNHS3dkNXJVK01LVW1FTkxXenNZTEVENUY2L0JDdU82TFEw?=
 =?utf-8?B?WGkyRiszalhpUitWK1laTWdzNUMwa2dNSWVnUjc1ZHlNNnlxZ3JxNGhZRTJO?=
 =?utf-8?B?dk9GalpqQTVDVEk3bk1zQ2xsd3FYbWFDWnVvWFNJUENBejc2VXdnWUhMNGVR?=
 =?utf-8?B?YW1PY0dNME5VelhtdUdyVmlRM2RNNHR0d015RVNaV0xDRUY1QmdEV3pNY3hJ?=
 =?utf-8?B?dlNuUDdNdjRzbDJKRWtrSUorWGVOd3BLYjlOanlGVWdwb0htUUt5VkRqRjdT?=
 =?utf-8?B?UUJQSDQ0eXhFL3VaOWZpSmovcnltRkxxR2gzNzdHNHVYaGJTUVc3M2VGaXFO?=
 =?utf-8?B?RDFqM1Y1ZDJhRmNwS3pHT2p3MnlkeG13SFlJVDBEMUVaSWg5aWxSSms5ZnNU?=
 =?utf-8?B?a1dTYVZQMTkyQ29nTkRKL2JVQ3FCVFN6dWpOdUlWVktNR3pNN05EcFcvTmQ0?=
 =?utf-8?B?RDhxN1B0QWduSDNSZmF4WGd6bWZCeDY4RERDSHBOd2w4b25pSjB1RVZZYWdo?=
 =?utf-8?B?UmxNZ0hKMVd4TUU2NDkzMzkyTi9wR21zR1JkMjEwVlpFVFVnUlZrUSt2WExC?=
 =?utf-8?B?K1BydVFJZ1RCZHBEN1hYVEZBRXlDSGgvQmpFQ053bDdOcUx4Mk9EWG94dlIz?=
 =?utf-8?B?UE5QSXFSN0VOeTBRME9KTU1PaEJueEQ3cDJnRU82d2lEdlpGQjBNdG80ZkR4?=
 =?utf-8?B?ZC9qalpnOVZVK3JjdG1BdWRLcHZBejFWeW1YNm85OVMwOExuRGRlL2grdUZO?=
 =?utf-8?B?YjJvS1lTTVRLU0sxNUZqcXJNZXhxYjIrbm9rdDl1cGc2TVlwMjcxcE0xQ2VJ?=
 =?utf-8?B?N0o0YzNFM3ZvU1V6Ti94c1hRMlJLbVRMamx5U0J0aUpVcnRGemt2enBuWTZt?=
 =?utf-8?B?ZHlDZW9wNHBDWlk4YnQ3OTk0ZVV0T254Z2c4WVNjd1prK3ZZaU10OTBGc09j?=
 =?utf-8?B?aGxxN3E4cHYrcmpKWFRjdmNUbXp2MUZFNUFRNHhRNmJ0cjBXdHh2MHFmZm1D?=
 =?utf-8?B?MWwweW9kOGZCbGZ2YVJ2bXAzMmp2bXdsVFJrdHIwczlPbUFZdUxzTVArNCtF?=
 =?utf-8?B?VzNLZnZYQWt2KzFNcTdWb2VudHl3YndUaWxXaERIQldnRjNzZUFuVm9WVXZP?=
 =?utf-8?B?MmFXZHlCSnJoRVdyTlF1RWJzZy9WbkNWbXNWVkY3cTM3dXB5Z3ZrNWxZMlFk?=
 =?utf-8?B?TkQzK3lNelplNVhqMGJNR3ZhZU95ZThSVERpci95bGpuWUEwdUplODlEdUVD?=
 =?utf-8?B?YW94T3VHdUVYaUNBU1JTT0ttZEgzcitMa3pVNXJDdE9qT1pUUVB1R0hXbWVn?=
 =?utf-8?B?ZHdhZ1BLWkRyQUltVzhxWlhtUTI1dkhVOW45NjQ5a2xGODIyL1ArK1ZvbS9X?=
 =?utf-8?B?QWdBQzErVkV6Um9GWCtwNisvQkFLRUlvZzQySUNJUTlJV1N3bktiSDNTRlRL?=
 =?utf-8?B?eFBtT3EvV29mMDlHRVF6TnFrLzRrN0FlVEVwR0k3VFVPdHZOMmkyQlJvTWFO?=
 =?utf-8?Q?tcFcScu/e7KpCrduw/b5sApmf?=
X-OriginatorOrg: amd.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 33d4251a-f7f3-42c8-854b-08dae211a4be
X-MS-Exchange-CrossTenant-AuthSource: MN0PR12MB6101.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Dec 2022 22:37:43.4179
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: i7ZWQ+2HpASOyLkgUUx74nFpJvrf0VWMe7W1UzNAm7KbjVpa5FilSqHykXTYC9tYh5Y7i1HXFN+aZxEgE5KKbg==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL0PR12MB4851
X-Spam-Status: No, score=-3.3 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A,RCVD_IN_DNSWL_NONE,
        RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS autolearn=ham
        autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 12/19/2022 00:40, Perry Yuan wrote:
> From: Perry Yuan <Perry.Yuan@amd.com>
> 
> The patch add AMD pstate EPP feature introduction and what EPP
> preference supported for AMD processors.

Don't use "the patch" or "this patch" in the commit message.

I would propose something like this:

> 
> User can get supported list from
> energy_performance_available_preferences attribute file, or update
> current profile to energy_performance_preference file


The amd-pstate driver supports a feature called energy performance
preference (EPP). Add information to the documentation to explain
how users can interact with the sysfs files for this feature.

> 
> 1) See all EPP profiles
> $ sudo cat /sys/devices/system/cpu/cpu0/cpufreq/energy_performance_available_preferences
> default performance balance_performance balance_power power
> 
> 2) Check current EPP profile
> $ sudo cat /sys/devices/system/cpu/cpu0/cpufreq/energy_performance_preference
> performance
> 
> 3) Set new EPP profile
> $ sudo bash -c "echo power > /sys/devices/system/cpu/cpu0/cpufreq/energy_performance_preference"
> 
> Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
> ---
>   Documentation/admin-guide/pm/amd-pstate.rst | 19 +++++++++++++++++++
>   1 file changed, 19 insertions(+)
> 
> diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
> index 06e23538f79c..33ab8ec8fc2f 100644
> --- a/Documentation/admin-guide/pm/amd-pstate.rst
> +++ b/Documentation/admin-guide/pm/amd-pstate.rst
> @@ -262,6 +262,25 @@ lowest non-linear performance in `AMD CPPC Performance Capability
>   <perf_cap_>`_.)
>   This attribute is read-only.
>   
> +``energy_performance_available_preferences``
> +
> +A list of all the supported EPP preferences that could be used for
> +``energy_performance_preference`` on this system.
> +These profiles represent different hints that are provided
> +to the low-level firmware about the user's desired energy vs efficiency
> +tradeoff.  ``default`` represents the epp value is set by platform
> +firmware. This attribute is read-only.
> +
> +``energy_performance_preference``
> +
> +The current energy performance preference can be read from this attribute.
> +and user can change current preference according to energy or performance needs
> +Please get all support profiles list from
> +``energy_performance_available_preferences`` attribute, all the profiles are
> +integer values defined between 0 to 255 when EPP feature is enabled by platform
> +firmware, if EPP feature is disabled, driver will ignore the written value
> +This attribute is read-write.
> +
>   Other performance and frequency values can be read back from
>   ``/sys/devices/system/cpu/cpuX/acpi_cppc/``, see :ref:`cppc_sysfs`.
>