linux-kernel - Re: [PATCH 2/2] iio: dac: stm32-dac: better handle reset controller failures

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Message-ID: <20200118143235.71a67b76@archlinux>
Date:   Sat, 18 Jan 2020 14:32:35 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Fabrice Gasnier <fabrice.gasnier@...com>
Cc:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <mcoquelin.stm32@...il.com>,
        <alexandre.torgue@...com>, <olivier.moysan@...com>,
        <linux-iio@...r.kernel.org>, <lars@...afoo.de>, <knaack.h@....de>,
        <pmeerw@...erw.net>, <linux-stm32@...md-mailman.stormreply.com>,
        <etienne.carriere@...com>
Subject: Re: [PATCH 2/2] iio: dac: stm32-dac: better handle reset controller
 failures

On Mon, 13 Jan 2020 14:14:26 +0100
Fabrice Gasnier <fabrice.gasnier@...com> wrote:

> From: Etienne Carriere <etienne.carriere@...com>
> 
> Use devm_reset_control_get_optional_exclusive() instead of
> devm_reset_control_get_exclusive() as reset controller is optional.
> 
> Nevertheless if reset controller is expected but reports an
> error, propagate the error code to the caller. In such case
> a nice error trace is emitted unless we're deferring the probe
> operation.
> 
> Signed-off-by: Etienne Carriere <etienne.carriere@...com>
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@...com>
Applied to the togreg branch of iio.git and pushed out as testing.

Thanks,

Jonathan

> ---
>  drivers/iio/dac/stm32-dac-core.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/dac/stm32-dac-core.c b/drivers/iio/dac/stm32-dac-core.c
> index 4d93446..7e5809b 100644
> --- a/drivers/iio/dac/stm32-dac-core.c
> +++ b/drivers/iio/dac/stm32-dac-core.c
> @@ -147,8 +147,16 @@ static int stm32_dac_probe(struct platform_device *pdev)
>  	priv->common.vref_mv = ret / 1000;
>  	dev_dbg(dev, "vref+=%dmV\n", priv->common.vref_mv);
>  
> -	rst = devm_reset_control_get_exclusive(dev, NULL);
> -	if (!IS_ERR(rst)) {
> +	rst = devm_reset_control_get_optional_exclusive(dev, NULL);
> +	if (rst) {
> +		if (IS_ERR(rst)) {
> +			ret = PTR_ERR(rst);
> +			if (ret != -EPROBE_DEFER)
> +				dev_err(dev, "reset get failed, %d\n", ret);
> +
> +			goto err_hw_stop;
> +		}
> +
>  		reset_control_assert(rst);
>  		udelay(2);
>  		reset_control_deassert(rst);