[PATCH net] net: hibmcge: fix page_pool DMA direction mismatch

[PATCH net] net: hibmcge: fix page_pool DMA direction mismatch

[Jijie Shao]

From: Jian Shen <shenjian15@huawei.com>

The driver memsets the RX buffer page head to zero before
submitting it to hardware, then calls dma_sync_single_for_device()
with DMA_TO_DEVICE.  This sync direction does not match the pool
dma_dir which is DMA_FROM_DEVICE, violating the DMA API contract
that the sync direction must match the mapping direction.

On swiotlb platforms the mismatch can cause incorrect bounce-buffer
behaviour, and CONFIG_DMA_API_DEBUG emits a warning.

Switch the page_pool dma_dir to DMA_BIDIRECTIONAL so that the
CPU-to-device memset sync becomes legal.

Fixes: c30595917585 ("net: hibmcge: add support for pagepool on rx")
Signed-off-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Jijie Shao <shaojijie@huawei.com>
---
 drivers/net/ethernet/hisilicon/hibmcge/hbg_txrx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/hisilicon/hibmcge/hbg_txrx.c b/drivers/net/ethernet/hisilicon/hibmcge/hbg_txrx.c
index 0ae314994676..3e6ae2aa0d4b 100644
--- a/drivers/net/ethernet/hisilicon/hibmcge/hbg_txrx.c
+++ b/drivers/net/ethernet/hisilicon/hibmcge/hbg_txrx.c
@@ -553,7 +553,7 @@ static int hbg_ring_page_pool_init(struct hbg_priv *priv, struct hbg_ring *ring)
 		.nid = dev_to_node(&priv->pdev->dev),
 		.dev = &priv->pdev->dev,
 		.napi = &ring->napi,
-		.dma_dir = DMA_FROM_DEVICE,
+		.dma_dir = DMA_BIDIRECTIONAL,
 		.offset = 0,
 		.max_len = hbg_get_page_size(ring),
 	};

base-commit: e2466392a0b8496000e12181cb1ee1535eb0da25
-- 
2.33.0

Re: [PATCH net] net: hibmcge: fix page_pool DMA direction mismatch

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Thu, 20 Aug 2026 20:43:46 +0800 you wrote:
> From: Jian Shen <shenjian15@huawei.com>
> 
> The driver memsets the RX buffer page head to zero before
> submitting it to hardware, then calls dma_sync_single_for_device()
> with DMA_TO_DEVICE.  This sync direction does not match the pool
> dma_dir which is DMA_FROM_DEVICE, violating the DMA API contract
> that the sync direction must match the mapping direction.
> 
> [...]

Here is the summary with links:
  - [net] net: hibmcge: fix page_pool DMA direction mismatch
    https://git.kernel.org/netdev/net/c/11efd7963dac

You are awesome, thank you!
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