netdev - Re: [net-next,v2] net: ethernet: rtsn: Add support for Renesas Ethernet-TSN

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Message-ID: <20240508125557.GG1385281@ragnatech.se>
Date: Wed, 8 May 2024 14:55:57 +0200
From: Niklas Söderlund <niklas.soderlund+renesas@...natech.se>
To: Andrew Lunn <andrew@...n.ch>
Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org, linux-renesas-soc@...r.kernel.org
Subject: Re: [net-next,v2] net: ethernet: rtsn: Add support for Renesas
 Ethernet-TSN

On 2024-05-08 14:33:24 +0200, Andrew Lunn wrote:
> On Wed, May 08, 2024 at 12:58:31PM +0200, Niklas Söderlund wrote:
> > On 2024-05-08 02:55:44 +0200, Andrew Lunn wrote:
> > > > +static int rtsn_probe(struct platform_device *pdev)
> > > > +{
> > > 
> > > 
> > > > +	pm_runtime_enable(&pdev->dev);
> > > > +	pm_runtime_get_sync(&pdev->dev);
> > > 
> > > 
> > > > +static int rtsn_remove(struct platform_device *pdev)
> > > > +{
> > > > +	struct rtsn_private *priv = platform_get_drvdata(pdev);
> > > > +
> > > > +	unregister_netdev(priv->ndev);
> > > > +	rtsn_mdio_free(priv);
> > > > +	rcar_gen4_ptp_unregister(priv->ptp_priv);
> > > > +	rtsn_change_mode(priv, OCR_OPC_DISABLE);
> > > > +	netif_napi_del(&priv->napi);
> > > > +
> > > > +	pm_runtime_put_sync(&pdev->dev);
> > > > +	pm_runtime_disable(&pdev->dev);
> > > 
> > > These appear to be the only two places you do any pm_ stuff. So it
> > > seems pointless. Maybe delete this for the moment, and come back later
> > > to add proper runtime power management?
> > 
> > I agree enable more PM stuff is a good candidate to follow initial 
> > entablement. But these pm_ calls are not pointless, I still need to deal 
> > with power. If I remove the pm_ calls things starts to fail.
> 
> That is odd. Why does it fail? What is turning the power off? Did i
> miss you registering some callbacks?

I agree it's odd and I will try to find out.

If I remove all pm_ calls and the include of pm_runtime.h register reads 
from the device do no longer works, so operating the device fails. Even 
if I dig out the root cause for this, is there any harm in keeping the 
pm_ operations in the initial entablement?

> 
>      Andrew

-- 
Kind Regards,
Niklas Söderlund