RE: [PATCH V9 3/5] i2c: tegra: Add DMA support

[Sowjanya Komatineni <skomatineni@nvidia.com>]

> >>>> +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.