Hi Arnd,
See inline...
Thanks,
with regards,
Ram
On Wed, Dec 31, 2014 at 8:21 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote:
> On Wednesday 31 December 2014 17:12:14 Rameshwar Prasad Sahu wrote:
>> This patch implements the APM X-Gene SoC DMA driver. The APM X-Gene
>> SoC DMA engine consists of 4 DMA channels for performing DMA operations.
>> These DMA operations include memory copy and scatter gathering offload.
>
> Is the dma engine capable of slave DMA in theory and you just don't use
> that, or does it not do that at all?
This DMA engine is not capable of slave DMA.
>
>> +static int xgene_dma_init_mem(struct xgene_dma *pdma)
>> +{
>> + int timeout = 1000;
>> +
>> + writel(0x0, pdma->csr_dma + DMA_MEM_RAM_SHUTDOWN);
>> +
>> + /* Force a barrier */
>> + readl(pdma->csr_dma + DMA_MEM_RAM_SHUTDOWN);
>> +
>> + do {
>> + if (readl(pdma->csr_dma + DMA_BLK_MEM_RDY)
>> + == DMA_BLK_MEM_RDY_DEFAULT)
>> + break;
>> + udelay(1);
>> + } while (--timeout);
>> +
>> + if (timeout <= 0) {
>> + dev_err(pdma->dev,
>> + "Failed to release memory from shutdown\n");
>> + return -ENODEV;
>> + }
>> + return 0;
>> +}
>
> That's a long busy-loop. Can you use a sleeping function instead?
Okay I will do this.
>
>> + /* Set DMA mask and coherent mask */
>> + ret = dma_coerce_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
>> + if (ret) {
>> + dev_err(&pdev->dev, "Failed to set DMA mask\n");
>> + goto err_pm_enable;
>> + }
>
> Never use dma_coerce_mask_and_coherent in new drivers. Instead, make
> sure that the information in the device tree is correct in the first
> place so the driver doesn't need to override it.
>
> Arnd
>
Okay I will use function for DMA masking that other driver uses.
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