Re: [PATCH] net: macb: Align the dma and coherent dma masks

[Nicolas Ferre]

On 09/02/2022 at 10:43, Harini Katakam wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>
> From: Marc St-Amand <mstamand@xxxxxxxxx>
>
> Single page and coherent memory blocks can use different DMA masks
> when the macb accesses physical memory directly. The kernel is clever
> enough to allocate pages that fit into the requested address width.
>
> When using the ARM SMMU, the DMA mask must be the same for single
> pages and big coherent memory blocks. Otherwise the translation
> tables turn into one big mess.
>
>    [   74.959909] macb ff0e0000.ethernet eth0: DMA bus error: HRESP not OK
>    [   74.959989] arm-smmu fd800000.smmu: Unhandled context fault: fsr=0x402, iova=0x3165687460, fsynr=0x20001, cbfrsynra=0x877, cb=1
>    [   75.173939] macb ff0e0000.ethernet eth0: DMA bus error: HRESP not OK
>    [   75.173955] arm-smmu fd800000.smmu: Unhandled context fault: fsr=0x402, iova=0x3165687460, fsynr=0x20001, cbfrsynra=0x877, cb=1
>
> Since using the same DMA mask does not hurt direct 1:1 physical
> memory mappings, this commit always aligns DMA and coherent masks.
>
> Signed-off-by: Marc St-Amand <mstamand@xxxxxxxxx>
> Signed-off-by: Harini Katakam <harini.katakam@xxxxxxxxxx>

Ok:
Acked-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxxxxxx>

Best regards,
  Nicolas

> ---
>   drivers/net/ethernet/cadence/macb_main.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index 1ce20bf52f72..4c231159b562 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -4765,7 +4765,7 @@ static int macb_probe(struct platform_device *pdev)
>
>   #ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
>          if (GEM_BFEXT(DAW64, gem_readl(bp, DCFG6))) {
> -               dma_set_mask(&pdev->dev, DMA_BIT_MASK(44));
> +               dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(44));
>                  bp->hw_dma_cap |= HW_DMA_CAP_64B;
>          }
>   #endif
> --
> 2.17.1


--
Nicolas Ferre