On 11/5/18, Chunyan Zhang <zhang.chunyan@xxxxxxxxxx> wrote:
> Some standard SD host controller can support both external dma
> controllers as well as ADMA in which the controller acts as
> DMA master.
>
> Currently the generic SDHCI code supports ADMA/SDMA integrated into
> the host controller but does not have any support for external DMA
> controllers implemented using dmaengine meaning that custom code is
> needed for any systems that use a generic DMA controller with SDHCI.
>
> Signed-off-by: Chunyan Zhang <zhang.chunyan@xxxxxxxxxx>
Looks good to me overall, but I think I found one small bug:
> + dma->rx_chan = dma_request_chan(mmc->parent, "rx");
> + if (IS_ERR(dma->rx_chan)) {
> + ret = PTR_ERR(dma->rx_chan);
> + if (ret == -EPROBE_DEFER && dma->tx_chan)
> + dma_release_channel(dma->tx_chan);
> +
> + dma->rx_chan = NULL;
> + pr_warn("Failed to request RX DMA channel.\n");
> + }
The error handling looks wrong here: if you get EPROBE_DEFER,
you want to skip the warning message. If you get any other error code,
you want the warning message and also the dma_release_channel()
which should be unconditional here.
Arnd
