[PATCH] net: stmmac: fixed the pbl setting with DT

[Byungho An <bh74.an@samsung.com>]

This patch fixed the pbl(programmable burst length) setting 
using DT. Even though the default pbl is 8, If there is no 
pbl property in device tree file, pbl is set 0 and it causes 
bandwidth degradation.

Signed-off-by: Byungho An <bh74.an@samsung.com>
---
 .../net/ethernet/stmicro/stmmac/stmmac_platform.c  |   20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index 98e1988..142ee8e 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -78,14 +78,18 @@ static int stmmac_probe_config_dt(struct platform_device *pdev,
 		plat->force_sf_dma_mode = 1;
 	}
 
-	dma_cfg = devm_kzalloc(&pdev->dev, sizeof(*dma_cfg), GFP_KERNEL);
-	if (!dma_cfg)
-		return -ENOMEM;
-
-	plat->dma_cfg = dma_cfg;
-	of_property_read_u32(np, "snps,pbl", &dma_cfg->pbl);
-	dma_cfg->fixed_burst = of_property_read_bool(np, "snps,fixed-burst");
-	dma_cfg->mixed_burst = of_property_read_bool(np, "snps,mixed-burst");
+	if (of_find_property(np, "snps,pbl", NULL)) {
+		dma_cfg = devm_kzalloc(&pdev->dev, sizeof(*dma_cfg),
+				       GFP_KERNEL);
+		if (!dma_cfg)
+			return -ENOMEM;
+		plat->dma_cfg = dma_cfg;
+		of_property_read_u32(np, "snps,pbl", &dma_cfg->pbl);
+		dma_cfg->fixed_burst =
+			of_property_read_bool(np, "snps,fixed-burst");
+		dma_cfg->mixed_burst =
+			of_property_read_bool(np, "snps,mixed-burst");
+	}
 
 	return 0;
 }
-- 
1.7.10.4