Re: [PATCH net-next 13/14] net: renesas: rswitch: Remove obsolete 32-bit DMA mask fallback
From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: 2026-09-03 09:43:17
Also in:
linux-renesas-soc, lkml
Hi Ruizhe, Thanks for your patch! On Thu, 3 Sept 2026 at 11:27, Ruizhe Zhou [off-list ref] wrote:
The DMA API guarantees support for masks of 32 bits or wider and
Really?
explicitly identifies retrying a 32-bit mask after a wider request as incorrect: https://docs.kernel.org/core-api/dma-api-howto.html#dma-addressing-capabilities
AFAIUI, that is only true iff the wider request is DMA_BIT_MASK(64).
Remove the obsolete fallback while retaining the error check so that a genuine DMA setup failure still aborts initialization.
Have you tested this on actual hardware, with/without IOMMU support?
quoted hunk ↗ jump to hunk
Signed-off-by: Ruizhe Zhou <redacted> --- drivers/net/ethernet/renesas/rswitch_main.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-)diff --git a/drivers/net/ethernet/renesas/rswitch_main.c b/drivers/net/ethernet/renesas/rswitch_main.c index 755232994fcc..64b821ca02f8 100644 --- a/drivers/net/ethernet/renesas/rswitch_main.c +++ b/drivers/net/ethernet/renesas/rswitch_main.c@@ -2162,11 +2162,8 @@ static int renesas_eth_sw_probe(struct platform_device *pdev) return -ENOMEM; ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(40)); - if (ret < 0) { - ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32)); - if (ret < 0) - return ret; - } + if (ret) + return ret; priv->gwca.index = AGENT_INDEX_GWCA; priv->gwca.num_queues = min(RSWITCH_NUM_PORTS * NUM_QUEUES_PER_NDEV,
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
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