linux-kernel - Re: [PATCH v2 6/9] spi: spi-s3c64xx: Check return values

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Message-ID: <fa403451-5f61-8edf-c696-2d020ec5b920@kernel.org>
Date:   Wed, 2 Sep 2020 10:14:01 +0200
From:   Sylwester Nawrocki <snawrocki@...nel.org>
To:     Lukasz Stelmach <l.stelmach@...sung.com>
Cc:     Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Andi Shyti <andi@...zian.org>, Mark Brown <broonie@...nel.org>,
        linux-spi@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        m.szyprowski@...sung.com, b.zolnierkie@...sung.com
Subject: Re: [PATCH v2 6/9] spi: spi-s3c64xx: Check return values

On 9/1/20 17:21, Lukasz Stelmach wrote:
> It was <2020-08-25 wto 21:06>, when Sylwester Nawrocki wrote:
>> On 8/21/20 18:13, Łukasz Stelmach wrote:
>>> Check return values in prepare_dma() and s3c64xx_spi_config() and
>>> propagate errors upwards.
>>>
>>> Signed-off-by: Łukasz Stelmach<l.stelmach@...sung.com>
>>> ---
>>>    drivers/spi/spi-s3c64xx.c | 47 ++++++++++++++++++++++++++++++++-------
>>>    1 file changed, 39 insertions(+), 8 deletions(-)
>>
>>> @@ -298,12 +299,24 @@ static void prepare_dma(struct s3c64xx_spi_dma_data *dma,
>>>      	desc = dmaengine_prep_slave_sg(dma->ch, sgt->sgl, sgt->nents,
>>>    				       dma->direction, DMA_PREP_INTERRUPT);
>>> +	if (!desc) {
>>> +		dev_err(&sdd->pdev->dev, "unable to prepare %s scatterlist",
>>> +			dma->direction == DMA_DEV_TO_MEM ? "rx" : "tx");
>>> +		return -ENOMEM;
>>> +	}
>>>      	desc->callback = s3c64xx_spi_dmacb;
>>>    	desc->callback_param = dma;
>>>      	dma->cookie = dmaengine_submit(desc);
>>> +	ret = dma_submit_error(dma->cookie);
>>> +	if (ret) {
>>> +		dev_err(&sdd->pdev->dev, "DMA submission failed");
>>> +		return -EIO;
>>
>> Just return the error value from dma_submit_error() here?
>>
> 
> --8<---------------cut here---------------start------------->8---
> static inline int dma_submit_error(dma_cookie_t cookie)
> {
>          return cookie < 0 ? cookie : 0;
> 
> }
> --8<---------------cut here---------------end--------------->8---
> 
> Not quite meaningful IMHO, is it?

dma_submit_error() returns 0 or an error code, I think it makes sense
to propagate that error code rather than replacing it with -EIO.