netdev - RE: [PATCH net-next] rswitch: Add PM ops

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Date: Fri, 13 Oct 2023 02:10:42 +0000
From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
To: Geert Uytterhoeven <geert@...ux-m68k.org>
CC: "s.shtylyov@....ru" <s.shtylyov@....ru>, "davem@...emloft.net"
	<davem@...emloft.net>, "edumazet@...gle.com" <edumazet@...gle.com>,
	"kuba@...nel.org" <kuba@...nel.org>, "pabeni@...hat.com" <pabeni@...hat.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>
Subject: RE: [PATCH net-next] rswitch: Add PM ops

Hi Geert-san,

> From: Geert Uytterhoeven, Sent: Thursday, October 12, 2023 9:35 PM
> 
> Hi Shimoda-san,
> 
> On Thu, Oct 12, 2023 at 2:16 PM Yoshihiro Shimoda
> <yoshihiro.shimoda.uh@...esas.com> wrote:
> > Add PM ops for Suspend to Idle. When the system suspended,
> > the Ethernet Serdes's clock will be stopped. So, this driver needs
> > to re-initialize the Ethernet Serdes by phy_init() in
> > renesas_eth_sw_resume(). Otherwise, timeout happened in phy_power_on().
> >
> > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
> 
> Thanks for your patch!

Thank you for your review!

> > --- a/drivers/net/ethernet/renesas/rswitch.c
> > +++ b/drivers/net/ethernet/renesas/rswitch.c
> > @@ -17,6 +17,7 @@
> >  #include <linux/of_net.h>
> >  #include <linux/phy/phy.h>
> >  #include <linux/platform_device.h>
> > +#include <linux/pm.h>
> >  #include <linux/pm_runtime.h>
> >  #include <linux/rtnetlink.h>
> >  #include <linux/slab.h>
> > @@ -1315,6 +1316,7 @@ static int rswitch_phy_device_init(struct rswitch_device *rdev)
> >         if (!phydev)
> >                 goto out;
> >         __set_bit(rdev->etha->phy_interface, phydev->host_interfaces);
> > +       phydev->mac_managed_pm = true;
> >
> >         phydev = of_phy_connect(rdev->ndev, phy, rswitch_adjust_link, 0,
> >                                 rdev->etha->phy_interface);
> > @@ -1991,11 +1993,52 @@ static void renesas_eth_sw_remove(struct platform_device *pdev)
> >         platform_set_drvdata(pdev, NULL);
> >  }
> >
> > +static int __maybe_unused renesas_eth_sw_suspend(struct device *dev)
> > +{
> > +       struct rswitch_private *priv = dev_get_drvdata(dev);
> > +       struct net_device *ndev;
> > +       int i;
> 
> unsigned int (also below)

I don't know why unsigned int is needed. Other functions use 
rswitch_for_each_enabled_port{_continue_reverse}() with int.
Especially, rswitch_for_each_enabled_port_continue_reverse()
has the following code, unsigned int will not work correctly:
---
#define rswitch_for_each_enabled_port_continue_reverse(priv, i) \
        for (i--; i >= 0; i--)                                  \
                if (priv->rdev[i]->disabled)                    \
                        continue;                               \
                else
---

So, I would like to keep this for consistency with other functions'
implementation. But, what do you think?

> > +
> > +       rswitch_for_each_enabled_port(priv, i) {
> > +               ndev = priv->rdev[i]->ndev;
> > +               if (netif_running(ndev)) {
> > +                       netif_device_detach(ndev);
> > +                       rswitch_stop(ndev);
> > +               }
> > +               if (priv->rdev[i]->serdes->init_count)
> > +                       phy_exit(priv->rdev[i]->serdes);
> 
> If !init_count, the PHY was not initialized before suspending? ...

Yes, it was possible if renesas_eth_sw_resume() called phy_init()
and it failed.

> > +       }
> > +
> > +       return 0;
> > +}
> > +
> > +static int __maybe_unused renesas_eth_sw_resume(struct device *dev)
> > +{
> > +       struct rswitch_private *priv = dev_get_drvdata(dev);
> > +       struct net_device *ndev;
> > +       int i;
> > +
> > +       rswitch_for_each_enabled_port(priv, i) {
> > +               phy_init(priv->rdev[i]->serdes);
> 
> ... while it is always initialized after resuming? Is that intentional,
> or should the pre-suspend state be preserved?

Yes, that is intentional. After this driver was probed, the phy was always
initialized.

> > +               ndev = priv->rdev[i]->ndev;
> > +               if (netif_running(ndev)) {
> > +                       rswitch_open(ndev);
> > +                       netif_device_attach(ndev);
> > +               }
> > +       }
> > +
> > +       return 0;
> > +}
> > +
> > +static SIMPLE_DEV_PM_OPS(renesas_eth_sw_pm_ops, renesas_eth_sw_suspend,
> > +                        renesas_eth_sw_resume);
> 
> Please use DEFINE_SIMPLE_DEV_PM_OPS() instead, so you can drop the
> __maybe_unused tags from the callbacks.

I got it. I'll fix them.

> > +
> >  static struct platform_driver renesas_eth_sw_driver_platform = {
> >         .probe = renesas_eth_sw_probe,
> >         .remove_new = renesas_eth_sw_remove,
> >         .driver = {
> >                 .name = "renesas_eth_sw",
> > +               .pm = &renesas_eth_sw_pm_ops,
> 
> pm_sleep_ptr(...)

I'll use it on v2.

Best regards,
Yoshihiro Shimoda

> >                 .of_match_table = renesas_eth_sw_of_table,
> >         }
> >  };
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds