On Fri, Jul 15, 2016 at 3:15 PM, Russell King - ARM Linux
<li...@armlinux.org.uk> wrote:
> On Fri, Jul 15, 2016 at 02:34:02PM +0530, Anup Patel wrote:
>> +static int uio_dmem_genirq_alloc_platdata(struct platform_device *pdev)
>> +{
>> + struct uio_dmem_genirq_pdata pdata;
>> + u32 dma_bits, regions;
>> + u32 sizes[MAX_UIO_MAPS];
>> + int ret;
>> +
>> + memset(&pdata, 0, sizeof(pdata));
>> +
>> + ret = of_property_read_u32(pdev->dev.of_node,
>> + uio_of_dma_bits_prop, &dma_bits);
>> + if (ret) {
>> + dev_err(&pdev->dev,
>> + "Missing property %s\n", uio_of_dma_bits_prop);
>> + return ret;
>> + }
>> + if (dma_bits > 64)
>> + dma_bits = 64;
>> +
>> + dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(dma_bits));
>
> You really need to check the return value from this: this function
> negotiates with the architecture, and if 64-bit DMA is not supported,
> then the call will fail and you as a driver are expected to fall back
> to 32-bit DMA only.
>
> In that case, you're expected to call the same function with a 32-bit
> mask, and if that fails, you're supposed to then decide that DMA is
> not possible.
>
Thanks for pointing out.
I will fix this as-per your suggestion in next revision.
Regards,
Anup
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