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

[Drewek, Wojciech]

> -----Original Message-----
> From: Shinas Rasheed <srasheed@xxxxxxxxxxx>
> Sent: Monday, October 23, 2023 1:45 PM
> To: netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Cc: hgani@xxxxxxxxxxx; vimleshk@xxxxxxxxxxx; Gallen, Erwan <egallen@xxxxxxxxxx>; mschmidt <mschmidt@xxxxxxxxxx>;
> pabeni@xxxxxxxxxx; horms@xxxxxxxxxx; kuba@xxxxxxxxxx; davem@xxxxxxxxxxxxx; Shinas Rasheed <srasheed@xxxxxxxxxxx>;
> Veerasenareddy Burru <vburru@xxxxxxxxxxx>; Sathesh Edara <sedara@xxxxxxxxxxx>; Eric Dumazet <edumazet@xxxxxxxxxx>
> 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@xxxxxxxxxxx>

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
>