linux-kernel - Re: [PATCH 1/5] drm/omap: Fix suspend resume regression after platform data removal

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Message-ID: <3f2855cc-48b8-ecb8-5d92-beeabe344b26@ti.com>
Date:   Tue, 16 Jun 2020 19:56:59 +0300
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     Tony Lindgren <tony@...mide.com>,
        Tomi Valkeinen <tomi.valkeinen@...com>
CC:     <linux-omap@...r.kernel.org>, "Andrew F . Davis" <afd@...com>,
        Dave Gerlach <d-gerlach@...com>,
        Faiz Abbas <faiz_abbas@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Keerthy <j-keerthy@...com>, Nishanth Menon <nm@...com>,
        Peter Ujfalusi <peter.ujfalusi@...com>,
        Roger Quadros <rogerq@...com>, Suman Anna <s-anna@...com>,
        Tero Kristo <t-kristo@...com>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <dri-devel@...ts.freedesktop.org>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>
Subject: Re: [PATCH 1/5] drm/omap: Fix suspend resume regression after
 platform data removal



On 16/06/2020 18:30, Tony Lindgren wrote:
> * Tomi Valkeinen <tomi.valkeinen@...com> [200616 13:02]:
>> On 11/06/2020 17:00, Grygorii Strashko wrote:
>>> I think, suspend might be fixed if all devices, which are now child of ti-sysc, will do
>>> pm_runtime_force_xxx() calls at noirq suspend stage by adding:
>>>
>>>       SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
>>>                         pm_runtime_force_resume)
>>>
>>> Am I missing smth?
>>
>> Isn't this almost exactly the same my patch does? I just used suspend_late
>> and resume_early. Is noirq phase better than late & early?
> 
> Well up to you as far as I'm concerned. The noirq phase comes with serious
> limitations, for let's say i2c bus usage if needed. Probably also harder
> to debug for suspend and resume.

Unfortunately, you can't use PM runtime force API at .suspend() stage as pm_runtime_get will still work and
there is no sync between suspend and pm_runtime.
The PM runtime force API can be used only during late/noirq as at this time pm_runtime is disabled.

-- 
Best regards,
grygorii