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client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C Received: from SATLEXMB04.amd.com (165.204.84.17) by SJ5PEPF000001EB.mail.protection.outlook.com (10.167.242.199) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.8901.15 via Frontend Transport; Tue, 8 Jul 2025 16:08:09 +0000 Received: from SATLEXMB03.amd.com (10.181.40.144) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Tue, 8 Jul 2025 11:08:03 -0500 Received: from [172.31.125.8] (10.180.168.240) by SATLEXMB03.amd.com (10.181.40.144) with Microsoft SMTP Server id 15.1.2507.39 via Frontend Transport; Tue, 8 Jul 2025 11:07:58 -0500 Message-ID: <41a78619-d9c6-4e2a-9684-056e91d09e64@amd.com> Date: Wed, 9 Jul 2025 00:07:57 +0800 Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 4/5] PM: hibernate: add new api pm_transition_event() To: Mario Limonciello , Samuel Zhang , , , , , , , , , , , , , , , CC: , , , , , , , , References: <20250708074248.1674924-1-guoqing.zhang@amd.com> <20250708074248.1674924-5-guoqing.zhang@amd.com> <1fa50a8e-9942-45c4-bef0-f31c23ef9923@amd.com> Content-Language: en-US From: "Zhang, GuoQing (Sam)" In-Reply-To: <1fa50a8e-9942-45c4-bef0-f31c23ef9923@amd.com> Content-Type: text/plain; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Jul 2025 16:08:09.5186 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: a66047fa-e720-47eb-bd21-08ddbe39a1fb X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SJ5PEPF000001EB.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA3PR12MB8810 On 2025/7/8 22:36, Mario Limonciello wrote: > On 7/8/2025 3:42 AM, Samuel Zhang wrote: >> dev_pm_ops.thaw() is called in following cases: >> * normal case: after hibernation image has been created. >> * error case 1: creation of a hibernation image has failed. >> * error case 2: restoration from a hibernation image has failed. >> >> For normal case, it is called mainly for resume storage devices for >> saving the hibernation image. Other devices that are not involved >> in the image saving do not need to resume the device. But since there's >> no api to know which case thaw() is called, device drivers can't >> conditionally resume device in thaw(). >> >> The new pm_transition_event() is such a api to query if thaw() is called >> in normal case. The returned value in thaw() is: >> * PM_EVENT_THAW: normal case, no need to resume non-storage devices. >> * PM_EVENT_RECOVER: error case, need to resume devices. >> >> Signed-off-by: Samuel Zhang >> --- >>   drivers/base/power/main.c |  5 +++++ >>   include/linux/pm.h        | 16 ++++++++++++++++ >>   2 files changed, 21 insertions(+) >> >> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c >> index 40e1d8d8a589..7e0982caa4d4 100644 >> --- a/drivers/base/power/main.c >> +++ b/drivers/base/power/main.c >> @@ -62,6 +62,11 @@ static LIST_HEAD(dpm_noirq_list); >>     static DEFINE_MUTEX(dpm_list_mtx); >>   static pm_message_t pm_transition; >> +int pm_transition_event(void) >> +{ >> +    return pm_transition.event; >> +} >> +EXPORT_SYMBOL_GPL(pm_transition_event); >>     static int async_error; >>   diff --git a/include/linux/pm.h b/include/linux/pm.h >> index 78855d794342..d1cb77ede1a2 100644 >> --- a/include/linux/pm.h >> +++ b/include/linux/pm.h >> @@ -657,6 +657,22 @@ struct pm_subsys_data { >>   #define DPM_FLAG_SMART_SUSPEND        BIT(2) >>   #define DPM_FLAG_MAY_SKIP_RESUME    BIT(3) >>   +/** >> + * pm_transition_event() - Query the current pm transition event value. >> + * >> + * Used to query the reason why thaw() is called. It will be one of >> 2 values: >> + * >> + * PM_EVENT_THAW: normal case. >> + *        hibernation image has been created. >> + * >> + * PM_EVENT_RECOVER: error case. >> + *        creation of a hibernation image or restoration of the main >> memory >> + *        contents from a hibernation image has failed. > > I don't believe this documentation is complete.  In the use in this > series those are two events used, but as this is now exported this > might be used by other callers later which could use it for other > PM_EVENT_*. > > So because of this I think it's best to convert the comment in > include/linux/pm.h to kdoc and then reference that from this kdoc. Hi Mario, thank you for the feedback. I don't have experience on kdoc. do you mean generate new `Documentation/power/pm.rst` from `include/linux/pm.h` using the `scripts/kernel-doc` tool? Could you give some guidance on this? Thank you! Regards Sam > >> + * >> + * Return: PM_EVENT_ messages >> + */ >> +int pm_transition_event(void); >> + >>   struct dev_pm_info { >>       pm_message_t        power_state; >>       bool            can_wakeup:1; >