Re: [PATCH] usb: dwc3: support 64 bit DMA in platform driver

[Christoph Hellwig]

On Sun, Jun 06, 2021 at 11:36:29AM +0200, Sven Peter wrote:
> +	/* Try to set 64-bit DMA first */
> +	if (WARN_ON(!dwc->sysdev->dma_mask))
> +		/* Platform did not initialize dma_mask */
> +		ret = dma_coerce_mask_and_coherent(dwc->sysdev,
> +						   DMA_BIT_MASK(64));
> +	else
> +		ret = dma_set_mask_and_coherent(dwc->sysdev, DMA_BIT_MASK(64));

WARN_ON + fallback seems weird.  I'd suggest to just error out for the
warn case.

> +	/* If seting 64-bit DMA mask fails, fall back to 32-bit DMA mask */
> +	if (ret) {
> +		ret = dma_set_mask_and_coherent(dwc->sysdev, DMA_BIT_MASK(32));
> +		if (ret)
> +			return ret;
> +	}

Setting a 64-bit mask will not fail.  No need for the fallback.