linux-kernel - Re: [PATCH 2/2] clk: imx95-blk-ctl: Save/restore registers when RPM routines are called

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Message-ID: <2dgzmsbzx5geriie4kaolwa6uw43etut55re4pxcvyvy34mlqr@33pynziwfzfc>
Date: Thu, 31 Jul 2025 10:31:25 +0300
From: Laurentiu Palcu <laurentiu.palcu@....nxp.com>
To: Frank Li <Frank.li@....com>
Cc: Abel Vesa <abelvesa@...nel.org>, Peng Fan <peng.fan@....com>, 
	Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, Shawn Guo <shawnguo@...nel.org>, 
	Sascha Hauer <s.hauer@...gutronix.de>, Pengutronix Kernel Team <kernel@...gutronix.de>, 
	Fabio Estevam <festevam@...il.com>, linux-clk@...r.kernel.org, imx@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] clk: imx95-blk-ctl: Save/restore registers when RPM
 routines are called

Hi Frank,

On Wed, Jul 30, 2025 at 12:23:46PM -0400, Frank Li wrote:
> On Wed, Jul 30, 2025 at 03:59:31PM +0300, Laurentiu Palcu wrote:
> > If runtime PM is used for the clock providers and they're part of a
> > power domain, then the power domain supply will be cut off when runtime
> > suspended. That means all BLK CTL registers belonging to that power
> > domain will be reset. Save the registers, then, before entering suspend
> > and restore them in resume.
> 
> Save the registers before entering suspend, then restore them in resume.
> 
> >
> > Also, fix the suspend/resume routines and make sure we disable/enable
> > the clock correctly.
> 
> Check runtime pm status in suspend/resume routines to make sure
> disable/enable clock correctly.

I think the current commit message is clear enough already and follows
the guidelines. Obviously, someone else could rephrase it differently
but I'm pretty happy with it in its current state. TBH, your suggested
changes neither add new information nor correct any grammar or spelling
mistakes, so I don't see a strong point in changing the commit message.

Thanks,
Laurentiu

> 
> >
> > Signed-off-by: Laurentiu Palcu <laurentiu.palcu@....nxp.com>
> > ---
> >  drivers/clk/imx/clk-imx95-blk-ctl.c | 33 ++++++++++++++++++-----------
> >  1 file changed, 21 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/clk/imx/clk-imx95-blk-ctl.c b/drivers/clk/imx/clk-imx95-blk-ctl.c
> > index c72debaf3a60b..56bed44719954 100644
> > --- a/drivers/clk/imx/clk-imx95-blk-ctl.c
> > +++ b/drivers/clk/imx/clk-imx95-blk-ctl.c
> > @@ -453,15 +453,24 @@ static int imx95_bc_runtime_suspend(struct device *dev)
> >  {
> >  	struct imx95_blk_ctl *bc = dev_get_drvdata(dev);
> >
> > +	bc->clk_reg_restore = readl(bc->base + bc->pdata->clk_reg_offset);
> >  	clk_disable_unprepare(bc->clk_apb);
> > +
> >  	return 0;
> >  }
> >
> >  static int imx95_bc_runtime_resume(struct device *dev)
> >  {
> >  	struct imx95_blk_ctl *bc = dev_get_drvdata(dev);
> > +	int ret;
> >
> > -	return clk_prepare_enable(bc->clk_apb);
> > +	ret = clk_prepare_enable(bc->clk_apb);
> > +	if (ret)
> > +		return ret;
> > +
> > +	writel(bc->clk_reg_restore, bc->base + bc->pdata->clk_reg_offset);
> > +
> > +	return 0;
> >  }
> >  #endif
> >
> > @@ -469,17 +478,12 @@ static int imx95_bc_runtime_resume(struct device *dev)
> >  static int imx95_bc_suspend(struct device *dev)
> >  {
> >  	struct imx95_blk_ctl *bc = dev_get_drvdata(dev);
> > -	int ret;
> >
> > -	if (bc->pdata->rpm_enabled) {
> > -		ret = pm_runtime_get_sync(bc->dev);
> > -		if (ret < 0) {
> > -			pm_runtime_put_noidle(bc->dev);
> > -			return ret;
> > -		}
> > -	}
> > +	if (pm_runtime_suspended(dev))
> > +		return 0;
> >
> >  	bc->clk_reg_restore = readl(bc->base + bc->pdata->clk_reg_offset);
> > +	clk_disable_unprepare(bc->clk_apb);
> >
> >  	return 0;
> >  }
> > @@ -487,11 +491,16 @@ static int imx95_bc_suspend(struct device *dev)
> >  static int imx95_bc_resume(struct device *dev)
> >  {
> >  	struct imx95_blk_ctl *bc = dev_get_drvdata(dev);
> > +	int ret;
> >
> > -	writel(bc->clk_reg_restore, bc->base + bc->pdata->clk_reg_offset);
> > +	if (pm_runtime_suspended(dev))
> > +		return 0;
> >
> > -	if (bc->pdata->rpm_enabled)
> > -		pm_runtime_put(bc->dev);
> > +	ret = clk_prepare_enable(bc->clk_apb);
> > +	if (ret)
> > +		return ret;
> > +
> > +	writel(bc->clk_reg_restore, bc->base + bc->pdata->clk_reg_offset);
> >
> >  	return 0;
> >  }
> > --
> > 2.46.1
> >