Re: [PATCH v1 2/3] net: bcmgenet: use optional max DMA burst size property

Nicolas Saenz Julienne
2019-10-11T19:01:51Z

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Hi Matthias!
One small comment, I'll test everything later on.

On Fri, 2019-10-11 at 20:48 +0200, matthias.bgg@kernel.org wrote:
> From: Matthias Brugger <mbrugger@suse.com>
>
> Depending on the HW, the maximal usable DMA burst size can vary.
> If not set accordingly a timeout in the transmit queue happens and no
> package can be sent. Read to optional max-burst-sz property, if not
> present, fallback to the standard value.
>
> Signed-off-by: Matthias Brugger <mbrugger@suse.com>
> ---
>
> drivers/net/ethernet/broadcom/genet/bcmgenet.c | 13 +++++++++++--
> drivers/net/ethernet/broadcom/genet/bcmgenet.h | 1 +
> 2 files changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
> b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
> index 12cb77ef1081..a7bb822a6d83 100644
> --- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
> +++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
> @@ -2576,7 +2576,8 @@ static int bcmgenet_init_dma(struct bcmgenet_priv *priv)
> }
>
> /* Init rDma */
> - bcmgenet_rdma_writel(priv, DMA_MAX_BURST_LENGTH, DMA_SCB_BURST_SIZE);
> + bcmgenet_rdma_writel(priv, priv->dma_max_burst_length,
> + DMA_SCB_BURST_SIZE);
>
> /* Initialize Rx queues */
> ret = bcmgenet_init_rx_queues(priv->dev);
> @@ -2589,7 +2590,8 @@ static int bcmgenet_init_dma(struct bcmgenet_priv *priv)
> }
>
> /* Init tDma */
> - bcmgenet_tdma_writel(priv, DMA_MAX_BURST_LENGTH, DMA_SCB_BURST_SIZE);
> + bcmgenet_tdma_writel(priv, priv->dma_max_burst_length,
> + DMA_SCB_BURST_SIZE);
>
> /* Initialize Tx queues */
> bcmgenet_init_tx_queues(priv->dev);
> @@ -3522,6 +3524,13 @@ static int bcmgenet_probe(struct platform_device *pdev)
>
> clk_prepare_enable(priv->clk);
>
> + if (dn) {
> + of_property_read_u32(dn, "dma-burst-sz",
> + &priv->dma_max_burst_length);

You set the 'dma-burst-sz' binding as optional, though this assumes that if a
device node is available dma_max_burst_length comes from the device tree. I
think you should check of_property_read_u32's return value and on failure
default to DMA_MAX_BURST_LENGTH.

> + } else {
> + priv->dma_max_burst_length = DMA_MAX_BURST_LENGTH;
> + }
> +
> bcmgenet_set_hw_params(priv);
>
> /* Mii wait queue */
> diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.h
> b/drivers/net/ethernet/broadcom/genet/bcmgenet.h
> index 4a8fc03d82fd..897f356eb376 100644
> --- a/drivers/net/ethernet/broadcom/genet/bcmgenet.h
> +++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.h
> @@ -663,6 +663,7 @@ struct bcmgenet_priv {
> bool crc_fwd_en;
>
> unsigned int dma_rx_chk_bit;
> + unsigned int dma_max_burst_length;
>
> u32 msg_enable;
>

Regards,
Nicolas

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