On Monday 05 October 2015 13:10:07 Jon Hunter wrote:
> Add support for the Tegra210 Audio DMA controller that is used for
> transferring data between system memory and the Audio sub-system.
> The driver only supports cyclic transfers because this is being solely
> used for audio.
>
> This driver is based upon the work by Dara Ramesh <dramesh@xxxxxxxxxx>.
>
> Signed-off-by: Jon Hunter <jonathanh@xxxxxxxxxx>
This version looks much better!
Just one small comment:
> + slave_req = dma_spec->args[0];
> + slave_dir = dma_spec->args[1];
> +
> + if (slave_req == 0)
> + return NULL;
> +
> + switch (slave_dir) {
> + case ADMA_AHUB_TO_MEM:
> + if (slave_req > tdma->rx_requests)
> + return NULL;
> +
> + if (tdma->rx_requests_reserved & BIT(slave_req))
> + return NULL;
> +
> + tdma->rx_requests_reserved |= BIT(slave_req);
> + break;
The rx_requests_reserved logic looks racy, if you have more than
one concurrent request or release. Better use atomic_test_and_set()
here and turn the variable into an atomic_t.
Arbd
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