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From:   Aisheng Dong <aisheng.dong@nxp.com>
To:     Laurentiu Tudor <laurentiu.tudor@nxp.com>,
        "linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
        Ying Zhang <ying.zhang22455@nxp.com>
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        "shawnguo@kernel.org" <shawnguo@kernel.org>,
        "s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
        "kernel@pengutronix.de" <kernel@pengutronix.de>,
        "festevam@gmail.com" <festevam@gmail.com>,
        dl-linux-imx <linux-imx@nxp.com>,
        "upstream-release@linux.nxdi.nxp.com" 
        <upstream-release@linux.nxdi.nxp.com>, Leo Li <leoyang.li@nxp.com>,
        Laurentiu Tudor <laurentiu.tudor@nxp.com>,
        Andy Duan <fugang.duan@nxp.com>,
        Clark Wang <xiaoning.wang@nxp.com>
Subject: RE: [RESEND] i2c: imx: defer probing on dma channel request
Thread-Topic: [RESEND] i2c: imx: defer probing on dma channel request
Thread-Index: AQHU4x+pU7Pzng1m0kSKhkHj16iqyqYgqMpw
Date:   Thu, 28 Mar 2019 07:31:20 +0000
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References: <20190325153016.12626-1-laurentiu.tudor@nxp.com>
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> From: laurentiu.tudor@nxp.com [mailto:laurentiu.tudor@nxp.com]
> Sent: Monday, March 25, 2019 11:30 PM
>=20
> From: Laurentiu Tudor <laurentiu.tudor@nxp.com>
>=20
> If the dma controller is not yet probed, defer i2c probe.
> The error path in probe was slightly modified (no functional change) to a=
void
> triggering this WARN_ON():
> "cg-pll0-div1 already disabled
> WARNING: CPU: 1 PID: 1 at drivers/clk/clk.c:828 clk_core_disable+0xa8/0xb=
0"

We may need more information to understand how this issue happens and it's =
also
better to put them in commit message to help review.

Regards
Dong Aisheng

>=20
> Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
> ---
>  drivers/i2c/busses/i2c-imx.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
>=20
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c =
index
> 42fed40198a0..4e34b1572756 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -1111,7 +1111,8 @@ static int i2c_imx_probe(struct platform_device
> *pdev)
>  				pdev->name, i2c_imx);
>  	if (ret) {
>  		dev_err(&pdev->dev, "can't claim irq %d\n", irq);
> -		goto clk_disable;
> +		clk_disable_unprepare(i2c_imx->clk);
> +		return ret;
>  	}
>=20
>  	/* Init queue */
> @@ -1161,19 +1162,25 @@ static int i2c_imx_probe(struct platform_device
> *pdev)
>  	pm_runtime_mark_last_busy(&pdev->dev);
>  	pm_runtime_put_autosuspend(&pdev->dev);
>=20
> +	/* Init DMA config if supported */
> +	ret =3D i2c_imx_dma_request(i2c_imx, phy_addr);
> +	if (ret) {
> +		if (ret !=3D -EPROBE_DEFER)
> +			dev_info(&pdev->dev, "can't use DMA, using PIO instead.\n");
> +		else
> +			goto del_adapter;
> +	}
> +
>  	dev_dbg(&i2c_imx->adapter.dev, "claimed irq %d\n", irq);
>  	dev_dbg(&i2c_imx->adapter.dev, "device resources: %pR\n", res);
>  	dev_dbg(&i2c_imx->adapter.dev, "adapter name: \"%s\"\n",
>  		i2c_imx->adapter.name);
>=20
> -	/* Init DMA config if supported */
> -	ret =3D i2c_imx_dma_request(i2c_imx, phy_addr);
> -	if (ret < 0)
> -		goto clk_notifier_unregister;
> -
>  	dev_info(&i2c_imx->adapter.dev, "IMX I2C adapter registered\n");
>  	return 0;   /* Return OK */
>=20
> +del_adapter:
> +	i2c_del_adapter(&i2c_imx->adapter);
>  clk_notifier_unregister:
>  	clk_notifier_unregister(i2c_imx->clk, &i2c_imx->clk_change_nb);
>  rpm_disable:
> @@ -1182,8 +1189,6 @@ static int i2c_imx_probe(struct platform_device
> *pdev)
>  	pm_runtime_set_suspended(&pdev->dev);
>  	pm_runtime_dont_use_autosuspend(&pdev->dev);
>=20
> -clk_disable:
> -	clk_disable_unprepare(i2c_imx->clk);
>  	return ret;
>  }
>=20
> --
> 2.17.1