Re: [dpdk-dev] [PATCH] i40e: Fix eth_i40e_dev_init sequence on ThunderX

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

On Thu, Nov 10, 2016 at 04:04:27AM -0800, Satha Rao wrote:
> i40e_asq_send_command: rd32 & wr32 under ThunderX gives unpredictable
>                        results. To solve this include rte memory barriers
> 
> Signed-off-by: Satha Rao <skoteshwar@caviumnetworks.com>
> ---
>  drivers/net/i40e/base/i40e_adminq.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/i40e/base/i40e_adminq.c b/drivers/net/i40e/base/i40e_adminq.c
> index 0d3a83f..1038a95 100644
> --- a/drivers/net/i40e/base/i40e_adminq.c
> +++ b/drivers/net/i40e/base/i40e_adminq.c
> @@ -832,6 +832,7 @@ enum i40e_status_code i40e_asq_send_command(struct i40e_hw *hw,
>  	}
>  
>  	val = rd32(hw, hw->aq.asq.head);
> +	rte_rmb();

use rte_smp_rmb() variant to avoid performance regression on x86

>  	if (val >= hw->aq.num_asq_entries) {
>  		i40e_debug(hw, I40E_DEBUG_AQ_MESSAGE,
>  			   "AQTX: head overrun at %d\n", val);
> @@ -929,8 +930,10 @@ enum i40e_status_code i40e_asq_send_command(struct i40e_hw *hw,
>  	(hw->aq.asq.next_to_use)++;
>  	if (hw->aq.asq.next_to_use == hw->aq.asq.count)
>  		hw->aq.asq.next_to_use = 0;
> -	if (!details->postpone)
> +	if (!details->postpone) {
>  		wr32(hw, hw->aq.asq.tail, hw->aq.asq.next_to_use);
> +		rte_wmb();

ditto

> +	}
>  
>  	/* if cmd_details are not defined or async flag is not set,
>  	 * we need to wait for desc write back
> -- 
> 2.7.4
>