linux-kernel - Re: [PATCH v2 1/1] phy: fsl-imx8-mipi-dphy: Hook into runtime pm

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Message-ID: <YDP6Smaor5uSTYKc@bogon.m.sigxcpu.org>
Date:   Mon, 22 Feb 2021 19:39:06 +0100
From:   Guido Günther <agx@...xcpu.org>
To:     Liu Ying <victor.liu@....com>
Cc:     Kishon Vijay Abraham I <kishon@...com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Robert Chiras <robert.chiras@....com>,
        Sam Ravnborg <sam@...nborg.org>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 1/1] phy: fsl-imx8-mipi-dphy: Hook into runtime pm

Hi Liu,
On Sat, Feb 20, 2021 at 01:37:29PM +0800, Liu Ying wrote:
> Hi Guido,
> 
> On Wed, 2020-12-16 at 12:27 +0100, Guido Günther wrote:
> > This allows us to shut down the mipi power domain on the imx8. The
> > alternative would be to drop the dphy from the mipi power domain in the
> > SOCs device tree and only have the DSI host controller visible there but
> > since the PD is mostly about the PHY that would defeat it's purpose.
> > 
> > This allows to shut off the power domain hen blanking the LCD panel:
> > 
> > pm_genpd_summary before:
> > 
> > domain                          status          slaves
> >     /device                                             runtime status
> > ----------------------------------------------------------------------
> > mipi                            on
> >     /devices/platform/soc@...oc@0:bus@...00000/30a00300.dphy  unsupported
> >     /devices/platform/soc@...oc@0:bus@...00000/30a00000.mipi_dsi  suspended
> > 
> > after:
> > 
> > mipi                            off-0
> >     /devices/platform/soc@...oc@0:bus@...00000/30a00300.dphy  suspended
> >     /devices/platform/soc@...oc@0:bus@...00000/30a00000.mipi_dsi  suspended
> > 
> > Signed-off-by: Guido Günther <agx@...xcpu.org>
> > ---
> >  .../phy/freescale/phy-fsl-imx8-mipi-dphy.c    | 22 ++++++++++++++++++-
> >  1 file changed, 21 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c b/drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c
> > index a95572b397ca..34e2d801e520 100644
> > --- a/drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c
> > +++ b/drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c
> > @@ -14,6 +14,7 @@
> >  #include <linux/of_platform.h>
> >  #include <linux/phy/phy.h>
> >  #include <linux/platform_device.h>
> > +#include <linux/pm_runtime.h>
> >  #include <linux/regmap.h>
> >  
> >  /* DPHY registers */
> > @@ -93,6 +94,7 @@ struct mixel_dphy_cfg {
> >  };
> >  
> >  struct mixel_dphy_priv {
> > +	struct device *dev;
> >  	struct mixel_dphy_cfg cfg;
> >  	struct regmap *regmap;
> >  	struct clk *phy_ref_clk;
> > @@ -382,6 +384,7 @@ static int mixel_dphy_power_on(struct phy *phy)
> >  	ret = clk_prepare_enable(priv->phy_ref_clk);
> >  	if (ret < 0)
> >  		return ret;
> > +	pm_runtime_get_sync(priv->dev);
> >  
> >  	phy_write(phy, PWR_ON, DPHY_PD_PLL);
> >  	ret = regmap_read_poll_timeout(priv->regmap, DPHY_LOCK, locked,
> > @@ -395,6 +398,7 @@ static int mixel_dphy_power_on(struct phy *phy)
> >  
> >  	return 0;
> >  clock_disable:
> > +	pm_runtime_put(priv->dev);
> >  	clk_disable_unprepare(priv->phy_ref_clk);
> >  	return ret;
> >  }
> > @@ -406,6 +410,7 @@ static int mixel_dphy_power_off(struct phy *phy)
> >  	phy_write(phy, PWR_OFF, DPHY_PD_PLL);
> >  	phy_write(phy, PWR_OFF, DPHY_PD_DPHY);
> >  
> > +	pm_runtime_put(priv->dev);
> >  	clk_disable_unprepare(priv->phy_ref_clk);
> >  
> >  	return 0;
> > @@ -467,6 +472,7 @@ static int mixel_dphy_probe(struct platform_device *pdev)
> >  	dev_dbg(dev, "phy_ref clock rate: %lu\n",
> >  		clk_get_rate(priv->phy_ref_clk));
> >  
> > +	priv->dev = dev;
> >  	dev_set_drvdata(dev, priv);
> >  
> >  	phy = devm_phy_create(dev, np, &mixel_dphy_phy_ops);
> > @@ -477,12 +483,26 @@ static int mixel_dphy_probe(struct platform_device *pdev)
> >  	phy_set_drvdata(phy, priv);
> >  
> >  	phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
> > +	if (IS_ERR(phy_provider))
> > +		return PTR_ERR(phy_provider);
> >  
> > -	return PTR_ERR_OR_ZERO(phy_provider);
> > +	pm_runtime_enable(dev);
> 
> If this enablement is done prior to devm_phy_create(), then the
> phy-core will manage runtime PM for this device.  This way, this driver
> doesn't have to manage it by itself.

That makes things simpler indeed. Fixed in v4 together with your other
comment.
Thanks!
 -- Guido

> 
> Regards,
> Liu Ying
> 
> > +
> > +	return 0;
> > +}
> > +
> > +static int mixel_dphy_remove(struct platform_device *pdev)
> > +{
> > +	struct mixel_dphy_priv *priv = platform_get_drvdata(pdev);
> > +
> > +	pm_runtime_disable(priv->dev);
> > +
> > +	return 0;
> >  }
> >  
> >  static struct platform_driver mixel_dphy_driver = {
> >  	.probe	= mixel_dphy_probe,
> > +	.remove = mixel_dphy_remove,
> >  	.driver = {
> >  		.name = "mixel-mipi-dphy",
> >  		.of_match_table	= mixel_dphy_of_match,
>