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SubjectRe: [PATCH 4/7] igbvf: eliminate duplicate barriers on weakly-ordered archs
On Tue, Mar 13, 2018 at 8:20 PM, Sinan Kaya <okaya@codeaurora.org> wrote:
> Code includes wmb() followed by writel(). writel() already has a barrier
> on some architectures like arm64.
>
> This ends up CPU observing two barriers back to back before executing the
> register write.
>
> Since code already has an explicit barrier call, changing writel() to
> writel_relaxed().
>
> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
> ---
> drivers/net/ethernet/intel/igbvf/netdev.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/intel/igbvf/netdev.c b/drivers/net/ethernet/intel/igbvf/netdev.c
> index 4214c15..fe3441b 100644
> --- a/drivers/net/ethernet/intel/igbvf/netdev.c
> +++ b/drivers/net/ethernet/intel/igbvf/netdev.c
> @@ -251,7 +251,7 @@ static void igbvf_alloc_rx_buffers(struct igbvf_ring *rx_ring,
> * such as IA-64).
> */
> wmb();
> - writel(i, adapter->hw.hw_addr + rx_ring->tail);
> + writel_relaxed(i, adapter->hw.hw_addr + rx_ring->tail);
> }
> }
>

This one missed the writel at the end of igbvf_tx_queue_adv().

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