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

[Lukasz Stelmach]

It was <2020-09-02 śro 10:14>, when Sylwester Nawrocki wrote:
> 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@xxxxxxxxxxx>
>>>> ---
>>>>    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.

It is not an error code that d_s_e() returns it is a value returned by
dma_cookie_assigned() called from within the tx_submit() operaton of a
DMA driver.

--8<---------------cut here---------------start------------->8---
static inline dma_cookie_t dma_cookie_assign(struct
dma_async_tx_descriptor *tx)
{
        struct dma_chan *chan = tx->chan;
        dma_cookie_t cookie;

        cookie = chan->cookie + 1;
        if (cookie < DMA_MIN_COOKIE)
                cookie = DMA_MIN_COOKIE;
        tx->cookie = chan->cookie = cookie;

        return cookie;
}
--8<---------------cut here---------------end--------------->8---

Yes, a non-zero value returned by d_s_e() indicates an error but it
definitely isn't one of error codes from errno*.h.

-- 
Łukasz Stelmach
Samsung R&D Institute Poland
Samsung Electronics

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