linux-kernel - Re: [PATCH v2] iio: adc: ti_am335x_adc: Fix return value check of tiadc_request

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Message-ID: <20231005150917.2d0c833e@jic23-huawei>
Date:   Thu, 5 Oct 2023 15:09:17 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Wadim Egorov <w.egorov@...tec.de>
Cc:     <lars@...afoo.de>, <robh@...nel.org>, <heiko@...ech.de>,
        <peter.ujfalusi@...com>, <mugunthanvnm@...com>,
        <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <nm@...com>, <upstream@...ts.phytec.de>,
        Bhavya Kapoor <b-kapoor@...com>
Subject: Re: [PATCH v2] iio: adc: ti_am335x_adc: Fix return value check of
 tiadc_request_dma()

On Mon, 25 Sep 2023 15:44:27 +0200
Wadim Egorov <w.egorov@...tec.de> wrote:

> Fix wrong handling of a DMA request where the probing only failed
> if -EPROPE_DEFER was returned. Instead, let us fail if a non -ENODEV
> value is returned. This makes DMAs explicitly optional. Even if the
> DMA request is unsuccessfully, the ADC can still work properly.
> We do also handle the defer probe case by making use of dev_err_probe().
> 
> Fixes: f438b9da75eb ("drivers: iio: ti_am335x_adc: add dma support")
> Signed-off-by: Wadim Egorov <w.egorov@...tec.de>

+CC Bhavya,

Could you take a look at this given you had comments on v1.

Thanks,

Jonathan

> ---
> v2:
>   - Update description
>   - Drop line break after Fixes tag
>   - Move decision about optional DMA into probe/caller
> ---
>  drivers/iio/adc/ti_am335x_adc.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
> index 8db7a01cb5fb..5f8795986995 100644
> --- a/drivers/iio/adc/ti_am335x_adc.c
> +++ b/drivers/iio/adc/ti_am335x_adc.c
> @@ -670,8 +670,10 @@ static int tiadc_probe(struct platform_device *pdev)
>  	platform_set_drvdata(pdev, indio_dev);
>  
>  	err = tiadc_request_dma(pdev, adc_dev);
> -	if (err && err == -EPROBE_DEFER)
> +	if (err && err != -ENODEV) {
> +		dev_err_probe(&pdev->dev, err, "DMA request failed\n");
>  		goto err_dma;
> +	}
>  
>  	return 0;
>