linux-kernel - Re: [PATCH] tty: serial: samsung: Set missing PM ops for hibernation support

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Message-ID: <47611b1a-8cea-acba-dbc3-bbbba9470d34@axis.com>
Date:   Wed, 9 Aug 2023 15:57:08 +0200
From:   Anton Eliasson <anton.eliasson@...s.com>
To:     Andi Shyti <andi.shyti@...nel.org>
CC:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-samsung-soc@...r.kernel.org>,
        <linux-serial@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <kernel@...s.com>
Subject: Re: [PATCH] tty: serial: samsung: Set missing PM ops for hibernation
 support

On 07/08/2023 23.34, Andi Shyti wrote:
> Hi Anton,
>
> On Mon, Aug 07, 2023 at 11:57:04AM +0200, Anton Eliasson wrote:
>> On 05/08/2023 23.38, Andi Shyti wrote:
>>> Hi Anton,
>>>
>>> On Thu, Aug 03, 2023 at 01:26:42PM +0200, Anton Eliasson wrote:
>>>> At least freeze, restore and thaw need to be set in order for the driver
>>>> to support system hibernation. The existing suspend/resume functions can
>>>> be reused since those functions don't touch the device's power state or
>>>> wakeup capability. Use the helper macros SET_SYSTEM_SLEEP_PM_OPS and
>>>> SET_NOIRQ_SYSTEM_SLEEP_PM_OPS for symmetry with similar drivers.
>>> and why do we need hibernation in this device?
>>>
>>> Andi
>> Hi!
>>
>> I wanted to test whether hibernation is possible on our SoC, even though it
>> is not a common feature on embedded ARM systems. This is the only mainline
>> driver that I found that needed modification, for my proof-of-concept
>> anyway, and I couldn't see any harm in the change.
> Thanks, makes sense, mine was just curiosity, can I know which
> SoC you are testing that is using the samsung serial device?
>
> You can add my r-b, anyway:
>
> Reviewed-by: Andi Shyti <andi.shyti@...nel.org>
>
> Thanks,
> Andi

It's the Axis Communications ARTPEC-8, an SoC for surveillance cameras: 
https://www.axis.com/solutions/system-on-chip

Thanks for the review!

Anton Eliasson