linux-kernel - Re: [PATCH V2 2/6] i3c: master: Mark last_busy on IBI when runtime PM is allowed

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Message-ID: <504a7276-53d3-467d-900d-eb9323a78223@intel.com>
Date: Thu, 5 Feb 2026 08:43:44 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: Frank Li <Frank.li@....com>
CC: <alexandre.belloni@...tlin.com>, <rafael@...nel.org>,
	<linux-i3c@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
	<linux-pm@...r.kernel.org>
Subject: Re: [PATCH V2 2/6] i3c: master: Mark last_busy on IBI when runtime PM
 is allowed

On 04/02/2026 23:45, Frank Li wrote:
> On Wed, Feb 04, 2026 at 08:24:21PM +0200, Adrian Hunter wrote:
>> On 04/02/2026 18:10, Frank Li wrote:
>>> On Wed, Feb 04, 2026 at 01:15:07PM +0200, Adrian Hunter wrote:
>>>> When an IBI can be received after the controller is
>>>> pm_runtime_put_autosuspend()'ed, the interrupt may occur just before the
>>>> device is auto-suspended.  In such cases, the runtime PM core may not see
>>>> any recent activity and may suspend the device earlier than intended.
>>>>
>>>> Mark the controller as last busy whenever an IBI is queued (when
>>>> rpm_ibi_allowed is set) so that the auto-suspend delay correctly reflects
>>>> recent bus activity and avoids premature suspension.
>>>>
>>>> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
>>>> ---
>>>
>>> Although it is no harmful, I think it is not necessary to mark last busy.
>>>
>>> schedule's workqueue task to do i3c transfer, which will call run time
>>> resume.
>>>
>>> Are sure it will block your function without this patch?
>>
>> It is not necessary at this time.  I wanted to cover the case
>> where an IBI is not followed by a transfer from the target
>> device driver.
> 
> look like it is impossible. Device raise IBI, which means device need do
> some things. otherwise, why raise IBI.

An IBI has a payload.  A device could provide all the data
in the IBI.

> 
> Let's defer this special case when we really meet in future.
Sure