linux-kernel - RE: [PATCH v2 0/2] reset: rzg2l-usbphy-ctrl: Add suspend to RAM support

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Message-ID:
 <TY3PR01MB11346C5EDDE82E779C69566BB86A7A@TY3PR01MB11346.jpnprd01.prod.outlook.com>
Date: Fri, 5 Dec 2025 13:45:56 +0000
From: Biju Das <biju.das.jz@...renesas.com>
To: Claudiu.Beznea <claudiu.beznea@...on.dev>, "p.zabel@...gutronix.de"
	<p.zabel@...gutronix.de>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>,
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: RE: [PATCH v2 0/2] reset: rzg2l-usbphy-ctrl: Add suspend to RAM
 support



> -----Original Message-----
> From: Claudiu Beznea <claudiu.beznea@...on.dev>
> Sent: 05 December 2025 13:30
> To: Biju Das <biju.das.jz@...renesas.com>; p.zabel@...gutronix.de
> Cc: linux-kernel@...r.kernel.org; linux-renesas-soc@...r.kernel.org; Claudiu Beznea
> <claudiu.beznea.uj@...renesas.com>
> Subject: Re: [PATCH v2 0/2] reset: rzg2l-usbphy-ctrl: Add suspend to RAM support
> 
> 
> 
> On 12/5/25 13:55, Biju Das wrote:
> > Hi Claudiu,
> >
> >> -----Original Message-----
> >> From: Biju Das
> >> Sent: 05 December 2025 10:57
> >> Subject: RE: [PATCH v2 0/2] reset: rzg2l-usbphy-ctrl: Add suspend to
> >> RAM support
> >>
> >>
> >> Hi Claudiu,
> >>
> >>> -----Original Message-----
> >>> From: Claudiu Beznea <claudiu.beznea@...on.dev>
> >>> Sent: 05 December 2025 10:47
> >>> Subject: Re: [PATCH v2 0/2] reset: rzg2l-usbphy-ctrl: Add suspend to
> >>> RAM support
> >>>
> >>>
> >>>
> >>> On 12/5/25 12:17, Biju Das wrote:
> >>>>
> >>>>
> >>>>> -----Original Message-----
> >>>>> From: Claudiu Beznea <claudiu.beznea@...on.dev>
> >>>>> Sent: 05 December 2025 10:00
> >>>>> To: Biju Das <biju.das.jz@...renesas.com>; p.zabel@...gutronix.de
> >>>>> Cc: linux-kernel@...r.kernel.org;
> >>>>> linux-renesas-soc@...r.kernel.org;
> >>>>> Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> >>>>> Subject: Re: [PATCH v2 0/2] reset: rzg2l-usbphy-ctrl: Add suspend
> >>>>> to RAM support
> >>>>>
> >>>>> Hi, Biju,
> >>>>>
> >>>>> On 12/5/25 10:53, Biju Das wrote:
> >>>>>>
> >>>>>>
> >>>>>> Hi Claudiu,
> >>>>>>
> >>>>>>> -----Original Message-----
> >>>>>>> From: Claudiu Beznea <claudiu.beznea@...on.dev>
> >>>>>>> Sent: 04 December 2025 18:26
> >>>>>>> Subject: Re: [PATCH v2 0/2] reset: rzg2l-usbphy-ctrl: Add
> >>>>>>> suspend to RAM support
> >>>>>>>
> >>>
> >>> From my previous experience with suspend/resume implementations, I
> >>> can say restoring the system in failure cases in suspend/resume or
> >>> not, is up to the subsystem maintainer. So, I'll let Philipp to
> >>> decide how he wants to go with it in this
> >> driver.
> >>>
> >>
> >> Agreed.
> >>
> >>> They are still supporting suspend to idle, where power is
> >>> maintained, right? Shouldn't we cover this case?
> >>
> >> Yes, I agree. Probably best thing is zero failures, if there is a
> >> failure in suspend path, the same device will fail in similar fashion, and the system never enters
> suspend state.
> >>
> >> So, report the failure and debug and fix the issue.
> >
> > FYI, On your resume path, if the below call fails, then there is a pm imbalance for next suspend().
> >
> > ret = pm_runtime_resume_and_get(dev);
> >
> > Similarly, if reset_assert() fails for a shared reset.
> 
> Wouldn't be the same if there will be no failure path code?


Eg:
ret = reset_control_deassert(priv->rstc);
+	if (ret)
+		goto pwrrdy_off;

Here you are skipping pm_runtime_resume_and_get(), The subsequent suspend()
Will lead to pm underflow error.

Similarly, on suspend() you are checking the error code of reset_assert(),
If it fails, you deassert it. Surprisingly, there is no deassert operation
On resume().


Cheers,
Biju