[PATCH] tty: serial: samsung: Set missing PM ops for hibernation support

[PATCH] tty: serial: samsung: Set missing PM ops for hibernation support

[Anton Eliasson]

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.

Signed-off-by: Anton Eliasson <anton.eliasson@axis.com>
---
I have not investigated the impact of adding the additional noirq
handler functions. The hardware that I tested on (Axis ARTPEC-8) appears
to work both with and without them assigned. Other similar drivers that
use noirq handlers assign them to both resume, thaw and restore so I
follow that style also.
---
 drivers/tty/serial/samsung_tty.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
index b29e9dfd81a6..e2247c11067d 100644
--- a/drivers/tty/serial/samsung_tty.c
+++ b/drivers/tty/serial/samsung_tty.c
@@ -2273,9 +2273,8 @@ static int s3c24xx_serial_resume_noirq(struct device *dev)
 }
 
 static const struct dev_pm_ops s3c24xx_serial_pm_ops = {
-	.suspend = s3c24xx_serial_suspend,
-	.resume = s3c24xx_serial_resume,
-	.resume_noirq = s3c24xx_serial_resume_noirq,
+	SET_SYSTEM_SLEEP_PM_OPS(s3c24xx_serial_suspend, s3c24xx_serial_resume)
+	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(NULL, s3c24xx_serial_resume_noirq)
 };
 #define SERIAL_SAMSUNG_PM_OPS	(&s3c24xx_serial_pm_ops)
 

---
base-commit: 06c2afb862f9da8dc5efa4b6076a0e48c3fbaaa5
change-id: 20230731-samsung_tty_pm_ops-7c98f309a4e9

Best regards,
-- 
Anton Eliasson <anton.eliasson@axis.com>


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

[Andi Shyti]

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

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

[Anton Eliasson]

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.


Anton Eliasson


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

[Andi Shyti]

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@kernel.org> 

Thanks,
Andi

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

[Anton Eliasson]

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@kernel.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


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

[Krzysztof Kozlowski]

On 03/08/2023 13:26, 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.
> 

Looks sensible, although you should also test the other sleep methods,
e.g. suspend to idle.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Best regards,
Krzysztof


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

[Anton Eliasson]

On 07/08/2023 15.50, Krzysztof Kozlowski wrote:
> On 03/08/2023 13:26, 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.
>>
> Looks sensible, although you should also test the other sleep methods,
> e.g. suspend to idle.
>
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>
> Best regards,
> Krzysztof
>
Yes, s2idle still works. Standby / Power-On Suspend and s2ram we don't 
have support for so I can't test it. Thanks for the review!


Anton Eliasson


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