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Date:   Fri, 9 Dec 2022 13:36:07 +0000
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Subject: Re: [PATCH] i2c: designware: Fix unbalanced suspended flag
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To:     Hans de Goede <hdegoede@redhat.com>, <wsa@kernel.org>,
        <jarkko.nikula@linux.intel.com>,
        <andriy.shevchenko@linux.intel.com>,
        <mika.westerberg@linux.intel.com>, <jsd@semihalf.com>
CC:     <linux-i2c@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <patches@opensource.cirrus.com>
References: <20221209114034.18025-1-rf@opensource.cirrus.com>
 <e9d113fb-5cd1-d93d-3d8f-fa9c1e55a8e2@redhat.com>
From:   Richard Fitzgerald <rf@opensource.cirrus.com>
In-Reply-To: <e9d113fb-5cd1-d93d-3d8f-fa9c1e55a8e2@redhat.com>
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On 9/12/22 12:15, Hans de Goede wrote:
> Hi Richard,
> 
> On 12/9/22 12:40, Richard Fitzgerald wrote:
>> Ensure that i2c_mark_adapter_suspended() is always balanced by a call to
>> i2c_mark_adapter_resumed().

<snip>

> 
> It is not entirely clear to me where the unbalance you claim to see comes
> from? When runtime-suspended SMART_SUSPEND should keep it suspended at which point
> the system suspend callback will never run ?
> 
> Are you sure that you are not maybe seeing a suspend/resume ordering issue?
> 
> Did you add printk messages to the suspend/resume callbacks of
> i2c-designware-platdrv.c which show the system suspend callback
> being called but not the system resume one ?
> 

With messages in strategic places.

[  169.607358] i2c_designware i2c_designware.2: PM: dev_pm_skip_suspend: 
SMART_SUSPEND=0 pm_runtime_status_suspended=1
[  169.607361] i2c_designware i2c_designware.2: PM: 
__device_suspend_late: dev_pm_skip_suspend:false
[  169.607364] i2c_designware i2c_designware.2: dw_i2c_plat_suspend
...
[  169.702511] i2c_designware i2c_designware.2: PM: dev_pm_skip_resume: 
1 because !power.must_resume
[  169.706241] i2c_designware i2c_designware.2: PM: dev_pm_skip_resume: 
1 because !power.must_resume
[  169.706244] i2c_designware i2c_designware.2: PM: device_resume_early: 
dev_pm_skip_resume:true
...
[  175.254832] i2c i2c-2: Transfer while suspended

(Just to prove my logging isn't lying, for i2c3 it reports
SMART_SUSPEND=1)

So it can skip the resume even if it didn't skip the suspend.
The SMART_SUSPEND flag is not set on i2c2 and the driver core can
skip resume even if it didn't skip suspend.