netdev - [PATCH RFC V2 3/6] net: bcmgenet: use optional max DMA burst size property

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Date:   Sat,  2 Nov 2019 14:41:30 +0100
From:   Stefan Wahren <wahrenst@....net>
To:     Matthias Brugger <matthias.bgg@...nel.org>,
        Matthias Brugger <mbrugger@...e.com>,
        "David S . Miller" <davem@...emloft.net>,
        Florian Fainelli <f.fainelli@...il.com>
Cc:     Eric Anholt <eric@...olt.net>,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        Doug Berger <opendmb@...il.com>, netdev@...r.kernel.org,
        bcm-kernel-feedback-list@...adcom.com,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH RFC V2 3/6] net: bcmgenet: use optional max DMA burst size property

From: Matthias Brugger <mbrugger@...e.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@...e.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 ac554a6..8d0093b 100644
--- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
@@ -2578,7 +2578,8 @@ 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);
@@ -2591,7 +2592,8 @@ 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);
@@ -3536,6 +3538,13 @@ 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);
+	} 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 7fbf573..22cde8c 100644
--- a/drivers/net/ethernet/broadcom/genet/bcmgenet.h
+++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.h
@@ -664,6 +664,7 @@ struct bcmgenet_priv {
 	bool crc_fwd_en;

 	unsigned int dma_rx_chk_bit;
+	unsigned int dma_max_burst_length;

 	u32 msg_enable;

--
2.7.4