netdev - RE: [PATCH 1/3] can: flexcan: add auto stop mode for IMX93 to support wakeup

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Date:   Wed, 30 Nov 2022 11:39:59 +0000
From:   Bough Chen <haibo.chen@....com>
To:     Marc Kleine-Budde <mkl@...gutronix.de>
CC:     "wg@...ndegger.com" <wg@...ndegger.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        dl-linux-imx <linux-imx@....com>,
        "linux-can@...r.kernel.org" <linux-can@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: RE: [PATCH 1/3] can: flexcan: add auto stop mode for IMX93 to support
 wakeup

> -----Original Message-----
> From: Marc Kleine-Budde <mkl@...gutronix.de>
> Sent: 2022年11月30日 18:54
> To: Bough Chen <haibo.chen@....com>
> Cc: wg@...ndegger.com; davem@...emloft.net; edumazet@...gle.com;
> kuba@...nel.org; pabeni@...hat.com; robh+dt@...nel.org;
> krzysztof.kozlowski+dt@...aro.org; shawnguo@...nel.org;
> s.hauer@...gutronix.de; kernel@...gutronix.de; festevam@...il.com;
> dl-linux-imx <linux-imx@....com>; linux-can@...r.kernel.org;
> netdev@...r.kernel.org; devicetree@...r.kernel.org
> Subject: Re: [PATCH 1/3] can: flexcan: add auto stop mode for IMX93 to support
> wakeup
> 
> On 22.11.2022 19:32:30, haibo.chen@....com wrote:
> > From: Haibo Chen <haibo.chen@....com>
> >
> > IMX93 do not contain a GPR to config the stop mode, it will set the
> > flexcan into stop mode automatically once the ARM core go into low
> > power mode (WFI instruct) and gate off the flexcan related clock
> > automatically. But to let these logic work as expect, before ARM core
> > go into low power mode, need to make sure the flexcan related clock
> > keep on.
> >
> > To support stop mode and wakeup feature on imx93, this patch add a new
> > fsl_imx93_devtype_data to separate from imx8mp.
> >
> > Signed-off-by: Haibo Chen <haibo.chen@....com>
> > ---
> >  drivers/net/can/flexcan/flexcan-core.c | 37 +++++++++++++++++++++++---
> >  drivers/net/can/flexcan/flexcan.h      |  2 ++
> >  2 files changed, 36 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/net/can/flexcan/flexcan-core.c
> > b/drivers/net/can/flexcan/flexcan-core.c
> > index 9bdadd716f4e..0aeff34e5ae1 100644
> > --- a/drivers/net/can/flexcan/flexcan-core.c
> > +++ b/drivers/net/can/flexcan/flexcan-core.c
> 
> [...]
> 
> > @@ -2299,8 +2322,16 @@ static int __maybe_unused
> flexcan_noirq_suspend(struct device *device)
> >  	if (netif_running(dev)) {
> >  		int err;
> >
> > -		if (device_may_wakeup(device))
> > +		if (device_may_wakeup(device)) {
> >  			flexcan_enable_wakeup_irq(priv, true);
> > +			/* For auto stop mode, need to keep the clock on before
> > +			 * system go into low power mode. After system go into
> > +			 * low power mode, hardware will config the flexcan into
> > +			 * stop mode, and gate off the clock automatically.
> > +			 */
> > +			if (priv->devtype_data.quirks &
> FLEXCAN_QUIRK_AUTO_STOP_MODE)
> > +				return 0;
> > +		}
> 
> With this change the flexcan_noirq_resume() is not symmetrical any more:
> pm_runtime_force_suspend() is not called for mx93, but
> pm_runtime_force_resume() is called.

Yes, I do not understand the logic of pm_runtime_force_suspend correctly. I also find there is an unbalance warning show up. My bad.

Will fix this and send a V2 patch.

Best Regards
Haibo Chen
> 
> >
> >  		err = pm_runtime_force_suspend(device);
> >  		if (err)
> 
> Marc
> 
> --
> Pengutronix e.K.                 | Marc Kleine-Budde           |
> Embedded Linux                   | https://www.pengutronix.de  |
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