> >>> + if (i2c_dev->has_dma) {
> >>> + ret = tegra_i2c_init_dma_param(i2c_dev, true);
> >>> + if (ret == -EPROBE_DEFER)
> >>> + goto disable_div_clk;
> >>> + ret = tegra_i2c_init_dma_param(i2c_dev, false);
> >>> + if (ret == -EPROBE_DEFER)
> >>> + goto disable_div_clk;
> >>
> >> So tegra_i2c_init_dma_param() could fail, printing a error message, and
> >> probe will succeed? If allocation fails during the driver's probe, then
> >> just fail the probe. Please give the rationale.
> >
> > If APB DMA probe doesn’t happen prior to tegra i2c, DMA is not available by
> > the time tegra_init_dma_param tries to request slave channel and in those
> > cases dma_request_slave_channel_reason will return EPROBE_DEFER for tegra
> > I2C probe to retry
> >
> > In case if DMA is available but DMA buffer allocation fails, then
> > tegra_i2c_init_dma_param returns ENOMEM and probe also fails returning same
> > ENOMEM
>
> Is that what you're going to change in the next version? Your current variant
> of the code doesn't fail the probe on ENOMEM and there is duplicated attempt
> to invoke tegra_i2c_init_dma_param() during the transfer.
Sorry correction to my previous reply. If DMA buffer allocation fails,
tegra_i2c_init_dma_param returns ENOMEM but probe will succeed as i2c
transaction need to happen during boot for some platform device programming
for successful boot and they use PIO mode as xfer bytes is less and deferring
i2c probe for ENOMEM causes boot to fail so during probe EPROBE_DEFER is only
taken care.
Re-attempt of tegra_i2c_init_dma_param in xfer happens only if no successful
DMA channel allocation happens prior to that ( during probe in case of ENOMEM).
DMA mode is mainly for large transfer, and i2c xfer returning failure due to
failing DMA buffer allocation causes boot to hang as platform device
programming need to happen which doesn’t need to use DMA.
Will fix this and will send updated patch to reattempt DMA request and buffer
allocation during DMA mode transfer and will return fail for DMA mode I2C
transfer...
Thanks
Sowjanya
