Re: [PATCH V2 net 1/2] net: hibmcge: disable Relaxed Ordering to fix RX packet corruption

[Jijie Shao]

on 2026/5/21 21:54, Paolo Abeni wrote:
> On 5/18/26 4:42 PM, Jijie Shao wrote:
> > 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>
> > ---
> >   drivers/net/ethernet/hisilicon/hibmcge/hbg_main.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/hisilicon/hibmcge/hbg_main.c b/drivers/net/ethernet/hisilicon/hibmcge/hbg_main.c
> > index 068da2fd1fea..319551caf047 100644
> > --- a/drivers/net/ethernet/hisilicon/hibmcge/hbg_main.c
> > +++ b/drivers/net/ethernet/hisilicon/hibmcge/hbg_main.c
> > @@ -420,6 +420,8 @@ 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);
> Sashiko noted this will not survive a device reset - that performs
> pci_restore_state - and you should likelly call pci_save_state(pdev)
> afterwards.

Yes, thank you. I will fix it in v3.
Jijie Shao