RE: [PATCH v2] event/cnxk: fix LMTST write for single event mode

[Pavan Nikhilesh Bhagavatula <pbhagavatula@marvell.com>]

> -----Original Message-----
> From: Srujana Challa <schalla@marvell.com>
> Sent: Wednesday, May 31, 2023 4:03 PM
> To: Pavan Nikhilesh Bhagavatula <pbhagavatula@marvell.com>; Shijith
> Thotton <sthotton@marvell.com>; Rahul Bhansali <rbhansali@marvell.com>;
> Jerin Jacob Kollanukkaran <jerinj@marvell.com>
> Cc: dev@dpdk.org; Srujana Challa <schalla@marvell.com>; Nithin Kumar
> Dabilpuram <ndabilpuram@marvell.com>
> Subject: [PATCH v2] event/cnxk: fix LMTST write for single event mode
> 
> LMTST area can be overwritten before read by HW between to consecutive
> steorl operations. Hence, add wmb() after steorl op to make sure
> the LMTST operation is complete.
> 
> Fixes: 313e884a22fd ("event/cnxk: support Tx adapter fast path")
> Cc: pbhagavatula@marvell.com
> 
> Signed-off-by: Srujana Challa <schalla@marvell.com>

Acked-by: Pavan Nikhilesh <pbhagavatula@marvell.com>

> ---
>  drivers/event/cnxk/cn10k_tx_worker.h | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/event/cnxk/cn10k_tx_worker.h
> b/drivers/event/cnxk/cn10k_tx_worker.h
> index c18786a14c..81fe31c4b9 100644
> --- a/drivers/event/cnxk/cn10k_tx_worker.h
> +++ b/drivers/event/cnxk/cn10k_tx_worker.h
> @@ -43,7 +43,6 @@ cn10k_sso_tx_one(struct cn10k_sso_hws *ws, struct
> rte_mbuf *m, uint64_t *cmd,
>  		 const uint64_t *txq_data, const uint32_t flags)
>  {
>  	uint8_t lnum = 0, loff = 0, shft = 0;
> -	uint16_t ref_cnt = m->refcnt;
>  	struct cn10k_eth_txq *txq;
>  	uintptr_t laddr;
>  	uint16_t segdw;
> @@ -98,10 +97,9 @@ cn10k_sso_tx_one(struct cn10k_sso_hws *ws, struct
> rte_mbuf *m, uint64_t *cmd,
> 
>  	roc_lmt_submit_steorl(lmt_id, pa);
> 
> -	if (flags & NIX_TX_OFFLOAD_MBUF_NOFF_F) {
> -		if (ref_cnt > 1)
> -			rte_io_wmb();
> -	}
> +	/* Memory barrier to make sure lmtst store completes */
> +	rte_io_wmb();
> +
>  	return 1;
>  }
> 
> --
> 2.25.1