[net-next PATCH 2/2] net: stmmac: add support for DMA Arbitration Scheme

[Christian Marangi <ansuelsmth@gmail.com>]

Add support for DMA Arbitration Scheme tune up to program the DMA to put
priority on Rx instead of applying Round-Robin logic.

This special DMA bus mode was defined in the header from a long time but
was never actually implemented. This option is used on the original
setup on the ipq806x-gmac driver based on DWMAC1000.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac1000_dma.c   | 3 +++
 drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 1 +
 include/linux/stmmac.h                                | 1 +
 3 files changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_dma.c
index daf79cdbd3ec..14eb7e8d61ea 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_dma.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_dma.c
@@ -104,6 +104,9 @@ static void dwmac1000_dma_init(void __iomem *ioaddr,
 	if (dma_cfg->aal)
 		value |= DMA_BUS_MODE_AAL;
 
+	if (dma_cfg->arbit)
+		value |= DMA_BUS_MODE_DA;
+
 	writel(value, ioaddr + DMA_BUS_MODE);
 
 	/* Mask interrupts by writing to CSR7 */
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index 843bd8804bfa..f5791b03b320 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -576,6 +576,7 @@ stmmac_probe_config_dt(struct platform_device *pdev, u8 *mac)
 	dma_cfg->pblx8 = !of_property_read_bool(np, "snps,no-pbl-x8");
 
 	dma_cfg->aal = of_property_read_bool(np, "snps,aal");
+	dma_cfg->arbit = of_property_read_bool(np, "snps,arbit");
 	dma_cfg->fixed_burst = of_property_read_bool(np, "snps,fixed-burst");
 	dma_cfg->mixed_burst = of_property_read_bool(np, "snps,mixed-burst");
 
diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
index c0079a7574ae..04a61f1eba90 100644
--- a/include/linux/stmmac.h
+++ b/include/linux/stmmac.h
@@ -97,6 +97,7 @@ struct stmmac_dma_cfg {
 	int fixed_burst;
 	int mixed_burst;
 	bool aal;
+	bool arbit;
 	bool eame;
 	bool multi_msi_en;
 	bool dche;
-- 
2.40.1