RE: [PATCH v3 11/18] qlcnic: Eliminate duplicate barriers on weakly-ordered archs

[Chopra, Manish]

> -----Original Message-----
> From: Sinan Kaya [mailto:okaya@xxxxxxxxxxxxxx]
> Sent: Friday, March 16, 2018 9:46 PM
> To: netdev@xxxxxxxxxxxxxxx; timur@xxxxxxxxxxxxxx; sulrich@xxxxxxxxxxxxxx
> Cc: linux-arm-msm@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> Sinan Kaya <okaya@xxxxxxxxxxxxxx>; Patil, Harish <Harish.Patil@xxxxxxxxxx>;
> Chopra, Manish <Manish.Chopra@xxxxxxxxxx>; Dept-GE Linux NIC Dev <Dept-
> GELinuxNICDev@xxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx
> Subject: [PATCH v3 11/18] qlcnic: Eliminate duplicate barriers on weakly-ordered
> archs
> 
> 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@xxxxxxxxxxxxxx>
> ---
>  drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_hw.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_hw.c
> b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_hw.c
> index 46b0372..97c146e7 100644
> --- a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_hw.c
> +++ b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_hw.c
> @@ -478,7 +478,7 @@ irqreturn_t qlcnic_83xx_clear_legacy_intr(struct
> qlcnic_adapter *adapter)
>  	wmb();
> 
>  	/* clear the interrupt trigger control register */
> -	writel(0, adapter->isr_int_vec);
> +	writel_relaxed(0, adapter->isr_int_vec);
>  	intr_val = readl(adapter->isr_int_vec);
>  	do {
>  		intr_val = readl(adapter->tgt_status_reg);
> --
> 2.7.4

Acked-by: Manish Chopra <manish.chopra@xxxxxxxxxx>

Thanks.