Re: [PATCH V4 07/11] clk: imx: scu: add suspend/resume support

From: Dong Aisheng <dongas86@gmail.com>
To: Stephen Boyd <sboyd@kernel.org>
Cc: Dong Aisheng <aisheng.dong@nxp.com>,
	linux-clk <linux-clk@vger.kernel.org>,
	"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
	<linux-arm-kernel@lists.infradead.org>,
	Michael Turquette <mturquette@baylibre.com>,
	Shawn Guo <shawnguo@kernel.org>,
	Fabio Estevam <fabio.estevam@nxp.com>,
	dl-linux-imx <linux-imx@nxp.com>,
	Sascha Hauer <kernel@pengutronix.de>
Subject: Re: [PATCH V4 07/11] clk: imx: scu: add suspend/resume support
Date: Mon, 9 Sep 2019 18:35:15 +0800	[thread overview]
Message-ID: <CAA+hA=Rds2Pvv0iJVhFr3nb0N8iKjTtO=uu8c_gTymiVr-dewA@mail.gmail.com> (raw)
In-Reply-To: <20190906170944.B861620578@mail.kernel.org>

On Sat, Sep 7, 2019 at 5:32 PM Stephen Boyd <sboyd@kernel.org> wrote:
>
> Quoting Dong Aisheng (2019-08-20 04:13:21)
> > Clock state will be lost when its power domain is completely off
> > during system suspend/resume. So we save and restore the state
> > accordingly in suspend/resume callback.
>
> And this doesn't need any coordination with other clks in the clk tree
> right?

AFAIK no as SC firmware may have handled it properly.

>
> > diff --git a/drivers/clk/imx/clk-scu.c b/drivers/clk/imx/clk-scu.c
> > index edc39d7..8d9cfa2 100644
> > --- a/drivers/clk/imx/clk-scu.c
> > +++ b/drivers/clk/imx/clk-scu.c
> > @@ -46,6 +46,10 @@ struct clk_scu {
> >         struct clk_hw hw;
> >         u16 rsrc_id;
> >         u8 clk_type;
> > +
> > +       /* for state save&restore */
> > +       bool is_enabled;
> > +       u32 rate;
> >  };
> >
> >  /*
> > @@ -425,6 +429,9 @@ struct clk_hw *__imx_clk_scu(struct device *dev, const char *name,
> >                 hw = ERR_PTR(ret);
> >         }
> >
> > +       if (dev)
> > +               dev_set_drvdata(dev, clk);
> > +
> >         return hw;
> >  }
> >
> > @@ -481,10 +488,52 @@ static int imx_clk_scu_probe(struct platform_device *pdev)
> >         return 0;
> >  }
> >
> > +int __maybe_unused imx_clk_scu_suspend(struct device *dev)
>
> static?
>
> > +{
> > +       struct clk_scu *clk = dev_get_drvdata(dev);
> > +
> > +       clk->rate = clk_hw_get_rate(&clk->hw);
> > +       clk->is_enabled = clk_hw_is_enabled(&clk->hw);
> > +
> > +       if (clk->rate)
> > +               dev_dbg(dev, "save rate %d\n", clk->rate);
> > +
> > +       if (clk->is_enabled)
> > +               dev_dbg(dev, "save enabled state\n");
> > +
> > +       return 0;
> > +}
> > +
> > +int __maybe_unused imx_clk_scu_resume(struct device *dev)
>
> static?
>
> > +{
> > +       struct clk_scu *clk = dev_get_drvdata(dev);
> > +       int ret = 0;
> > +
> > +       if (clk->rate) {
> > +               ret = clk_scu_set_rate(&clk->hw, clk->rate, 0);
> > +               dev_dbg(dev, "restore rate %d %s\n", clk->rate,
> > +                       !ret ? "success" : "failed");
> > +       }
> > +
> > +       if (clk->is_enabled) {
> > +               ret = clk_scu_prepare(&clk->hw);
> > +               dev_dbg(dev, "restore enabled state %s\n",
> > +                       !ret ? "success" : "failed");
> > +       }
> > +
> > +       return ret;
> > +}
> > +
> > +const struct dev_pm_ops imx_clk_scu_pm_ops = {
>
> static?
>

Sorry that i missed to update here as those function are changed to be
used within
this file now.
Will fix.

Regards
Aisheng

> > +       SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(imx_clk_scu_suspend,
> > +                                     imx_clk_scu_resume)
> > +};
> > +