[PATCH v6 07/12] usb: chipidea: add a usb2 driver for ci13xxx

On Thu, Sep 25, 2014 at 09:11:35AM +0200, Arnd Bergmann wrote:

On Thursday 25 September 2014 09:16:48 Peter Chen wrote:

quoted

quoted

+     }
+
+     if (dev->of_node) {
+             ret = ci_hdrc_usb2_dt_probe(dev, ci_pdata);
+             if (ret)
+                     goto clk_err;
+     } else {
+             ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
+             if (ret)
+                     goto clk_err;
+     }

Hi Antoine, the above code may not be needed, since get phy and set dma
mask are common operation, we can do it at core code, the only thing you
need to do is something like: dev->dma_mask = DMA_BIT_MASK(32).

Certainly not, doing that would be broken for a number of reasons:

- dev->dma_mask is a pointer, a driver should not reassign that
- the device may have been set up for a bus that requires a smaller mask
  that is already set, changing the mask would cause data corruption
- setting just the dma mask but not coherent mask is wrong
- setting the dma mask can fail, e.g. if the mask is smaller than the
  smallest memory zone, so you have to check the return value.

In current chipidea structure, the parent (glue layer) driver will not be
used for dma, udc/host driver uses dma mask from child (core layer), at core
layer we will do:


	pdev->dev.dma_mask = dev->dma_mask; /* this device is parent */
	dma_set_coherent_mask(&pdev->dev, dev->coherent_dma_mask);

Would you suggestion us a suitable way? Or it is ok we use just Antoine's way that
call dma_coerce_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32)) at parent
driver no matter dt or non-dt? Thanks.

-- 
Best Regards,
Peter Chen