[PATCH V3 net 1/2] net: hibmcge: disable Relaxed Ordering to fix RX packet corruption

[Jijie Shao]

When SMMU is disabled, the hibmcge driver may receive corrupted packets.
The hardware writes packet data and descriptors to the same page, but
with Relaxed Ordering enabled, PCI write transactions may not be
strictly ordered. This can cause the driver to observe a valid
descriptor before the corresponding packet data is fully written.

Fix this by clearing PCI_EXP_DEVCTL_RELAX_EN in the PCI bridge control
register to ensure strict write ordering between packet data and
descriptors.

Fixes: f72e25594061 ("net: hibmcge: Implement rx_poll function to receive packets")
Signed-off-by: Jijie Shao <shaojijie@xxxxxxxxxx>
---
ChangeLog:
v2 -> v3:
  - Use pci_save_state () to ensure that Relaxed Ordering is disabled after the reset,
    suggested Paolo.
  v2: https://lore.kernel.org/all/20260518144253.1568118-2-shaojijie@xxxxxxxxxx/
---
 drivers/net/ethernet/hisilicon/hibmcge/hbg_main.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/hisilicon/hibmcge/hbg_main.c b/drivers/net/ethernet/hisilicon/hibmcge/hbg_main.c
index 068da2fd1fea..f721e9893804 100644
--- a/drivers/net/ethernet/hisilicon/hibmcge/hbg_main.c
+++ b/drivers/net/ethernet/hisilicon/hibmcge/hbg_main.c
@@ -420,6 +420,9 @@ static int hbg_pci_init(struct pci_dev *pdev)
 		return -ENOMEM;
 
 	pci_set_master(pdev);
+	pcie_capability_clear_word(pdev, PCI_EXP_DEVCTL,
+				   PCI_EXP_DEVCTL_RELAX_EN);
+	pci_save_state(pdev);
 	return 0;
 }
 
-- 
2.33.0