netdev - Re: [EXT] Re: [PATCH net v2] net: fec: add a check for CONFIG

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Message-ID: <CANhBUQ1VZMV4MKqs95mJnZPLeDnhAgjgLTSaqL_pY08GGzM-mQ@mail.gmail.com>
Date:   Sat, 16 Nov 2019 22:00:21 +0800
From:   Chuhong Yuan <hslester96@...il.com>
To:     Andy Duan <fugang.duan@....com>
Cc:     David Miller <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [EXT] Re: [PATCH net v2] net: fec: add a check for CONFIG_PM to
 avoid clock count mis-match

On Sat, Nov 16, 2019 at 2:57 PM Andy Duan <fugang.duan@....com> wrote:
>
> From: David Miller <davem@...emloft.net> Sent: Saturday, November 16, 2019 4:11 AM
> > From: Chuhong Yuan <hslester96@...il.com>
> > Date: Tue, 12 Nov 2019 19:28:30 +0800
> >
> > > If CONFIG_PM is enabled, runtime pm will work and call runtime_suspend
> > > automatically to disable clks.
> > > Therefore, remove only needs to disable clks when CONFIG_PM is disabled.
> > > Add this check to avoid clock count mis-match caused by double-disable.
> > >
> > > Fixes: c43eab3eddb4 ("net: fec: add missed clk_disable_unprepare in
> > > remove")
> > > Signed-off-by: Chuhong Yuan <hslester96@...il.com>
> >
> > Your explanation in your reply to my feedback still doesn't explain the
> > situation to me.
> >
> > For every clock enable done during probe, there must be a matching clock
> > disable during remove.
> >
> > Period.
> >
> > There is no CONFIG_PM guarding the clock enables during probe in this driver,
> > therefore there should be no reason to require CONFIG_PM guards to the
> > clock disables during the remove method,
> >
> > You have to explain clearly, and in detail, why my logic and analysis of this
> > situation is not correct.
> >
> > And when you do so, you will need to add those important details to the
> > commit message of this change and submit a v3.
> >
> > Thank you.
>
> I agree with David. Below fixes is more reasonable.
> Chuhong, if there has no voice about below fixes, you can submit v3 later.
>

I get confused that how does this work to solve the CONFIG_PM problem.
And why do we need to adjust the position of the latter four functions?
I need to explain them in the commit message.

> @@ -3636,6 +3636,11 @@ fec_drv_remove(struct platform_device *pdev)
>         struct net_device *ndev = platform_get_drvdata(pdev);
>         struct fec_enet_private *fep = netdev_priv(ndev);
>         struct device_node *np = pdev->dev.of_node;
> +       int ret;
> +
> +       ret = pm_runtime_get_sync(&pdev->dev);
> +       if (ret < 0)
> +               return ret;
>
>         cancel_work_sync(&fep->tx_timeout_work);
>         fec_ptp_stop(pdev);
> @@ -3643,15 +3648,17 @@ fec_drv_remove(struct platform_device *pdev)
>         fec_enet_mii_remove(fep);
>         if (fep->reg_phy)
>                 regulator_disable(fep->reg_phy);
> -       pm_runtime_put(&pdev->dev);
> -       pm_runtime_disable(&pdev->dev);
> -       clk_disable_unprepare(fep->clk_ahb);
> -       clk_disable_unprepare(fep->clk_ipg);
> +
>         if (of_phy_is_fixed_link(np))
>                 of_phy_deregister_fixed_link(np);
>         of_node_put(fep->phy_node);
>         free_netdev(ndev);
>
> +       clk_disable_unprepare(fep->clk_ahb);
> +       clk_disable_unprepare(fep->clk_ipg);
> +       pm_runtime_put_noidle(&pdev->dev);
> +       pm_runtime_disable(&pdev->dev);
> +
>         return 0;
>  }
>
> Regards,
> Fugang Duan