Re: [PATCH v7 1/1] i2c: lpi2c: use clk notifier for rate changes

From: Alexander Stein <alexander.stein@ew.tq-group.com>
To: Andi Shyti <andi.shyti@kernel.org>
Cc: Dong Aisheng <aisheng.dong@nxp.com>,
	Shawn Guo <shawnguo@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Fabio Estevam <festevam@gmail.com>, Wolfram Sang <wsa@kernel.org>,
	Alexander Sverdlin <alexander.sverdlin@siemens.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	NXP Linux Team <linux-imx@nxp.com>,
	linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v7 1/1] i2c: lpi2c: use clk notifier for rate changes
Date: Wed, 08 Nov 2023 07:46:12 +0100	[thread overview]
Message-ID: <22082032.EfDdHjke4D@steina-w> (raw)
In-Reply-To: <20231107212049.csimqzzvim5uecpa@zenone.zhora.eu>

Hi Andi,

Am Dienstag, 7. November 2023, 22:20:49 CET schrieb Andi Shyti:
> Hi Alexander,
> 
> is it my mail client not working or is is your patch that has
> gone through something terribly bad?

I can't see anything obviously wrong. Can you elaborate?

Thanks
Alexander

> Andi
> 
> On Tue, Nov 07, 2023 at 03:12:01PM +0100, Alexander Stein wrote:
> > * CLKLO = I2C_CLK_RATIO * CLKHI, SETHOLD = CLKHI, DATAVD = CLKHI/2 */
> > 
> >  static int lpi2c_imx_config(struct lpi2c_imx_struct *lpi2c_imx)
> >  {
> > 
> > @@ -207,7 +224,7 @@ static int lpi2c_imx_config(struct lpi2c_imx_struct
> > *lpi2c_imx)> 
> >  	lpi2c_imx_set_mode(lpi2c_imx);
> > 
> > -	clk_rate = clk_get_rate(lpi2c_imx->clks[0].clk);
> > +	clk_rate = atomic_read(&lpi2c_imx->rate_per);
> > 
> >  	if (!clk_rate)
> >  	
> >  		return -EINVAL;
> > 
> > @@ -590,6 +607,27 @@ static int lpi2c_imx_probe(struct platform_device
> > *pdev)> 
> >  	if (ret)
> >  	
> >  		return ret;
> > 
> > +	lpi2c_imx->clk_change_nb.notifier_call = lpi2c_imx_clk_change_cb;
> > +	ret = devm_clk_notifier_register(&pdev->dev, lpi2c_imx->clks[0].clk,
> > +					 &lpi2c_imx->clk_change_nb);
> > +	if (ret)
> > +		return dev_err_probe(&pdev->dev, ret,
> > +				     "can't register peripheral clock 
notifier\n");
> > +	/*
> > +	 * Lock the clock rate to avoid rate change between clk_get_rate() 
and
> > +	 * atomic_set()
> > +	 */
> > +	ret = clk_rate_exclusive_get(lpi2c_imx->clks[0].clk);
> > +	if (ret)
> > +		return dev_err_probe(&pdev->dev, ret,
> > +				     "can't lock I2C peripheral clock 
rate\n");
> > +
> > +	atomic_set(&lpi2c_imx->rate_per, clk_get_rate(lpi2c_imx-
>clks[0].clk));
> > +	clk_rate_exclusive_put(lpi2c_imx->clks[0].clk);
> > +	if (!atomic_read(&lpi2c_imx->rate_per))
> > +		return dev_err_probe(&pdev->dev, -EINVAL,
> > +				     "can't get I2C peripheral clock 
rate\n");
> > +
> > 
> >  	pm_runtime_set_autosuspend_delay(&pdev->dev, I2C_PM_TIMEOUT);
> >  	pm_runtime_use_autosuspend(&pdev->dev);
> >  	pm_runtime_get_noresume(&pdev->dev);

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