Re: [PATCH 1/1] PCI: layerscape-ep: set 64-bit DMA mask

[Christophe JAILLET]

Le 21/09/2023 à 17:37, Frank Li a écrit :
> From: Guanhua Gao <guanhua.gao@xxxxxxx>
>
> Set DMA mask and coherent DMA mask to enable 64-bit addressing.
>
> Signed-off-by: Guanhua Gao <guanhua.gao@xxxxxxx>
> Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@xxxxxxx>
> Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
> ---
>   drivers/pci/controller/dwc/pci-layerscape-ep.c | 5 +++++
>   1 file changed, 5 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/pci-layerscape-ep.c b/drivers/pci/controller/dwc/pci-layerscape-ep.c
> index de4c1758a6c33..6fd0dea38a32c 100644
> --- a/drivers/pci/controller/dwc/pci-layerscape-ep.c
> +++ b/drivers/pci/controller/dwc/pci-layerscape-ep.c
> @@ -249,6 +249,11 @@ static int __init ls_pcie_ep_probe(struct platform_device *pdev)
>   
>   	pcie->big_endian = of_property_read_bool(dev->of_node, "big-endian");
>   
> +	/* set 64-bit DMA mask and coherent DMA mask */
> +	if (dma_set_mask_and_coherent(dev, DMA_BIT_MASK(64)))
> +		if (dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32)))

As stated in [1], dma_set_mask() with a 64-bit mask will never
fail if dev->dma_mask is non-NULL.

So, if it fails, the 32 bits case will also fail for the same reason.
There is no need for the 2nd test.


See [1] for Christoph Hellwig comment about it.

CJ


[1]: https://lkml.org/lkml/2021/6/7/398

> +			return -EIO;
> +
>   	platform_set_drvdata(pdev, pcie);
>   
>   	ret = dw_pcie_ep_init(&pci->ep);