linux-kernel - RE: [PATCH net-next 1/3] octeon_ep: remove dma sync in trasmit path

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Message-ID: <MW4PR11MB5776017470E5871819D93D5BFDD8A@MW4PR11MB5776.namprd11.prod.outlook.com>
Date:   Mon, 23 Oct 2023 12:02:31 +0000
From:   "Drewek, Wojciech" <wojciech.drewek@...el.com>
To:     Shinas Rasheed <srasheed@...vell.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "hgani@...vell.com" <hgani@...vell.com>,
        "vimleshk@...vell.com" <vimleshk@...vell.com>,
        "Gallen, Erwan" <egallen@...hat.com>,
        mschmidt <mschmidt@...hat.com>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "horms@...nel.org" <horms@...nel.org>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        Veerasenareddy Burru <vburru@...vell.com>,
        Sathesh Edara <sedara@...vell.com>,
        Eric Dumazet <edumazet@...gle.com>
Subject: RE: [PATCH net-next 1/3] octeon_ep: remove dma sync in trasmit path



> -----Original Message-----
> From: Shinas Rasheed <srasheed@...vell.com>
> Sent: Monday, October 23, 2023 1:45 PM
> To: netdev@...r.kernel.org; linux-kernel@...r.kernel.org
> Cc: hgani@...vell.com; vimleshk@...vell.com; Gallen, Erwan <egallen@...hat.com>; mschmidt <mschmidt@...hat.com>;
> pabeni@...hat.com; horms@...nel.org; kuba@...nel.org; davem@...emloft.net; Shinas Rasheed <srasheed@...vell.com>;
> Veerasenareddy Burru <vburru@...vell.com>; Sathesh Edara <sedara@...vell.com>; Eric Dumazet <edumazet@...gle.com>
> Subject: [PATCH net-next 1/3] octeon_ep: remove dma sync in trasmit path
> 
> Cleanup dma sync calls for scatter gather
> mappings in trasmit path
> 
> Signed-off-by: Shinas Rasheed <srasheed@...vell.com>

Hi Shinas,

The commit msg only says what changed without justification.
What is the reasoning behind those changes?

> ---
>  drivers/net/ethernet/marvell/octeon_ep/octep_main.c | 7 -------
>  1 file changed, 7 deletions(-)
> 
> diff --git a/drivers/net/ethernet/marvell/octeon_ep/octep_main.c b/drivers/net/ethernet/marvell/octeon_ep/octep_main.c
> index 552970c7dec0..bf1e376a4232 100644
> --- a/drivers/net/ethernet/marvell/octeon_ep/octep_main.c
> +++ b/drivers/net/ethernet/marvell/octeon_ep/octep_main.c
> @@ -869,9 +869,6 @@ static netdev_tx_t octep_start_xmit(struct sk_buff *skb,
>  		if (dma_mapping_error(iq->dev, dma))
>  			goto dma_map_err;
> 
> -		dma_sync_single_for_cpu(iq->dev, tx_buffer->sglist_dma,
> -					OCTEP_SGLIST_SIZE_PER_PKT,
> -					DMA_TO_DEVICE);
>  		memset(sglist, 0, OCTEP_SGLIST_SIZE_PER_PKT);
>  		sglist[0].len[3] = len;
>  		sglist[0].dma_ptr[0] = dma;
> @@ -891,10 +888,6 @@ static netdev_tx_t octep_start_xmit(struct sk_buff *skb,
>  			frag++;
>  			si++;
>  		}
> -		dma_sync_single_for_device(iq->dev, tx_buffer->sglist_dma,
> -					   OCTEP_SGLIST_SIZE_PER_PKT,
> -					   DMA_TO_DEVICE);
> -
>  		hw_desc->dptr = tx_buffer->sglist_dma;
>  	}
> 
> --
> 2.25.1
>