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SubjectRe: [PATCH V9 3/5] i2c: tegra: Add DMA support
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02.02.2019 21:43, Sowjanya Komatineni пишет:
>
>>>>>> +static int tegra_i2c_init_dma(struct tegra_i2c_dev *i2c_dev) {
>>>>>> + struct dma_chan *dma_chan;
>>>>>> + u32 *dma_buf;
>>>>>> + dma_addr_t dma_phys;
>>>>>> + int err = 0;
>>>>>> +
>>>>>> + if (!IS_ENABLED(CONFIG_TEGRA20_APB_DMA))
>>>>>> + return -ENODEV;
>>>>>
>>>>> Driver shall not fail to probe if DMA driver is disabled, but to continue with the PIO-only mode available.
>>>>>
>>>>> Should be:
>>>>>
>>>>> if (!IS_ENABLED(CONFIG_TEGRA20_APB_DMA))
>>>>> return 0;
>>>>>
>>>> Except EPROBE_DEFER, anything else returned from tegra_i2c_init_dma
>>>> (ENODEV/ENOMEM) is ignored in i2c_probe DMA mode decision is based on xfer size and availability of dma channel or can be changed based on valid dma buf to shorten the line.
>>>>
>>>
>>> Ah, sorry. I missed that, seems good then.
>>>
>>
>> BTW, it may be worthwhile to move out the error code handling into tegra_i2c_init_dma() for clarity. It also won't hurt to not ignore errors other than -ENODEV.
>
> Either ways are same. To be more readable/clear on error types for diff cases and errors that we are ignoring, I am explicitly keeping error codecs (EPROBE_DEFER/ENODEV/ENOMEM) same way.
> Also in probe for readability checking with EPROBE_DEFER which explicitly indicating we keep deferring i2c probe rather than simple return.
>

Okay, then please add a error message for the dma_chan request-failure, printing a message that tells error code for the case (or even regardless) of errno != -ENODEV.

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