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From: Alexander Lobakin <aleksander.lobakin@intel•com>
To: Petr Machata <petrm@nvidia•com>, Amit Cohen <amcohen@nvidia•com>
Cc: <netdev@vger•kernel.org>, Andrew Lunn <andrew+netdev@lunn•ch>,
	"David S. Miller" <davem@davemloft•net>,
	Eric Dumazet <edumazet@google•com>,
	"Jakub Kicinski" <kuba@kernel•org>,
	Paolo Abeni <pabeni@redhat•com>, Simon Horman <horms@kernel•org>,
	Danielle Ratson <danieller@nvidia•com>,
	Ido Schimmel <idosch@nvidia•com>, <mlxsw@nvidia•com>,
	Jiri Pirko <jiri@resnulli•us>
Subject: Re: [PATCH net 3/5] mlxsw: pci: Sync Rx buffers for device
Date: Fri, 25 Oct 2024 17:02:44 +0200	[thread overview]
Message-ID: <a68cedfb-cd9e-4b93-a99e-ae30b9c837eb@intel.com> (raw)
In-Reply-To: <92e01f05c4f506a4f0a9b39c10175dcc01994910.1729866134.git.petrm@nvidia.com>

From: Petr Machata <petrm@nvidia•com>
Date: Fri, 25 Oct 2024 16:26:27 +0200

> From: Amit Cohen <amcohen@nvidia•com>
> 
> Non-coherent architectures, like ARM, may require invalidating caches
> before the device can use the DMA mapped memory, which means that before
> posting pages to device, drivers should sync the memory for device.
> 
> Sync for device can be configured as page pool responsibility. Set the
> relevant flag and define max_len for sync.
> 
> Cc: Jiri Pirko <jiri@resnulli•us>
> Fixes: b5b60bb491b2 ("mlxsw: pci: Use page pool for Rx buffers allocation")
> Signed-off-by: Amit Cohen <amcohen@nvidia•com>
> Reviewed-by: Ido Schimmel <idosch@nvidia•com>
> Signed-off-by: Petr Machata <petrm@nvidia•com>
> ---
>  drivers/net/ethernet/mellanox/mlxsw/pci.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlxsw/pci.c b/drivers/net/ethernet/mellanox/mlxsw/pci.c
> index 2320a5f323b4..d6f37456fb31 100644
> --- a/drivers/net/ethernet/mellanox/mlxsw/pci.c
> +++ b/drivers/net/ethernet/mellanox/mlxsw/pci.c
> @@ -996,12 +996,13 @@ static int mlxsw_pci_cq_page_pool_init(struct mlxsw_pci_queue *q,
>  	if (cq_type != MLXSW_PCI_CQ_RDQ)
>  		return 0;
>  
> -	pp_params.flags = PP_FLAG_DMA_MAP;
> +	pp_params.flags = PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV;
>  	pp_params.pool_size = MLXSW_PCI_WQE_COUNT * mlxsw_pci->num_sg_entries;
>  	pp_params.nid = dev_to_node(&mlxsw_pci->pdev->dev);
>  	pp_params.dev = &mlxsw_pci->pdev->dev;
>  	pp_params.napi = &q->u.cq.napi;
>  	pp_params.dma_dir = DMA_FROM_DEVICE;
> +	pp_params.max_len = PAGE_SIZE;

max_len is the maximum HW-writable area of a buffer. Headroom and
tailroom must be excluded. In your case

	pp_params.max_len = PAGE_SIZE - MLXSW_PCI_RX_BUF_SW_OVERHEAD;

>  
>  	page_pool = page_pool_create(&pp_params);
>  	if (IS_ERR(page_pool))

Thanks,
Olek

  reply	other threads:[~2024-10-25 15:03 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-10-25 14:26 [PATCH net 0/5] mlxsw: Fixes Petr Machata
2024-10-25 14:26 ` [PATCH net 1/5] mlxsw: spectrum_ptp: Add missing verification before pushing Tx header Petr Machata
2024-10-25 14:26 ` [PATCH net 2/5] mlxsw: pci: Sync Rx buffers for CPU Petr Machata
2024-10-25 15:00   ` Alexander Lobakin
2024-10-27  7:29     ` Amit Cohen
2024-10-25 14:26 ` [PATCH net 3/5] mlxsw: pci: Sync Rx buffers for device Petr Machata
2024-10-25 15:02   ` Alexander Lobakin [this message]
2024-10-27  6:51     ` Amit Cohen
2024-10-29 15:12       ` Alexander Lobakin
2024-10-25 14:26 ` [PATCH net 4/5] mlxsw: spectrum_ipip: Fix memory leak when changing remote IPv6 address Petr Machata
2024-10-25 14:26 ` [PATCH net 5/5] selftests: forwarding: Add IPv6 GRE remote change tests Petr Machata
2024-10-31  1:30 ` [PATCH net 0/5] mlxsw: Fixes patchwork-bot+netdevbpf

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