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[PATCH v3 3/6] net: stmmac: stmmac_platform: fix parsing of DT binding

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From: Niklas Cassel <niklas.cassel@axis.com>

commit 64c3b252e9fc ("net: stmmac: fixed the pbl setting with DT")
changed the parsing of the DT binding.

Before 64c3b252e9fc, snps,fixed-burst and snps,mixed-burst were parsed
regardless if the property snps,pbl existed or not.
After the commit, fixed burst and mixed burst are only parsed if
snps,pbl exists. Now when snps,aal has been added, it too is only
parsed if snps,pbl exists.

Since the DT binding does not specify that fixed burst, mixed burst
or aal depend on snps,pbl being specified, undo changes introduced
by 64c3b252e9fc.

The issue commit 64c3b252e9fc ("net: stmmac: fixed the pbl setting with
DT") tries to address is solved in another way:
The databook specifies that all values other than
1, 2, 4, 8, 16, or 32 results in undefined behavior,
so snps,pbl = <0> is invalid.

If pbl is 0 after parsing, set pbl to DEFAULT_DMA_PBL.
This handles the case where the property is omitted, and also handles
the case where the property is specified without any data.

Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c  |  4 +--
 .../net/ethernet/stmicro/stmmac/stmmac_platform.c  | 29 +++++++++++-----------
 2 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index b1e42ddf0370..b5188122bc15 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -1581,8 +1581,8 @@ static int stmmac_init_dma_engine(struct stmmac_priv *priv)
 	int atds = 0;
 	int ret = 0;
 
-	if (!priv->plat->dma_cfg) {
-		dev_err(priv->device, "DMA configuration not found\n");
+	if (!priv->plat->dma_cfg || !priv->plat->dma_cfg->pbl) {
+		dev_err(priv->device, "Invalid DMA configuration\n");
 		return -EINVAL;
 	}
 
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index d3b6f92f350a..81800f23a9c4 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -304,21 +304,22 @@ stmmac_probe_config_dt(struct platform_device *pdev, const char **mac)
 		plat->force_sf_dma_mode = 1;
 	}
 
-	if (of_find_property(np, "snps,pbl", NULL)) {
-		dma_cfg = devm_kzalloc(&pdev->dev, sizeof(*dma_cfg),
-				       GFP_KERNEL);
-		if (!dma_cfg) {
-			stmmac_remove_config_dt(pdev, plat);
-			return ERR_PTR(-ENOMEM);
-		}
-		plat->dma_cfg = dma_cfg;
-		of_property_read_u32(np, "snps,pbl", &dma_cfg->pbl);
-		dma_cfg->aal = of_property_read_bool(np, "snps,aal");
-		dma_cfg->fixed_burst =
-			of_property_read_bool(np, "snps,fixed-burst");
-		dma_cfg->mixed_burst =
-			of_property_read_bool(np, "snps,mixed-burst");
+	dma_cfg = devm_kzalloc(&pdev->dev, sizeof(*dma_cfg),
+			       GFP_KERNEL);
+	if (!dma_cfg) {
+		stmmac_remove_config_dt(pdev, plat);
+		return ERR_PTR(-ENOMEM);
 	}
+	plat->dma_cfg = dma_cfg;
+
+	of_property_read_u32(np, "snps,pbl", &dma_cfg->pbl);
+	if (!dma_cfg->pbl)
+		dma_cfg->pbl = DEFAULT_DMA_PBL;
+
+	dma_cfg->aal = of_property_read_bool(np, "snps,aal");
+	dma_cfg->fixed_burst = of_property_read_bool(np, "snps,fixed-burst");
+	dma_cfg->mixed_burst = of_property_read_bool(np, "snps,mixed-burst");
+
 	plat->force_thresh_dma_mode = of_property_read_bool(np, "snps,force_thresh_dma_mode");
 	if (plat->force_thresh_dma_mode) {
 		plat->force_sf_dma_mode = 0;
-- 
2.1.4

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[PATCH v3 0/6] net: stmmac: make DMA programmable burst length more configurable Niklas Cassel <niklas.cassel@axis.com> - 2016-12-07 15:30 +0100
  [PATCH v3 3/6] net: stmmac: stmmac_platform: fix parsing of DT binding Niklas Cassel <niklas.cassel@axis.com> - 2016-12-07 15:30 +0100
    Re: [PATCH v3 3/6] net: stmmac: stmmac_platform: fix parsing of DT  binding Alexandre Torgue <alexandre.torgue@st.com> - 2016-12-08 10:10 +0100
      Re: [PATCH v3 3/6] net: stmmac: stmmac_platform: fix parsing of DT  binding Niklas Cassel <niklas.cassel@axis.com> - 2016-12-08 10:50 +0100
        Re: [PATCH v3 3/6] net: stmmac: stmmac_platform: fix parsing of DT  binding Alexandre Torgue <alexandre.torgue@st.com> - 2016-12-08 11:00 +0100
  [PATCH v3 6/6] net: smmac: allow configuring lower pbl values Niklas Cassel <niklas.cassel@axis.com> - 2016-12-07 15:30 +0100
    Re: [PATCH v3 6/6] net: smmac: allow configuring lower pbl values Alexandre Torgue <alexandre.torgue@st.com> - 2016-12-08 11:50 +0100
      Re: [PATCH v3 6/6] net: smmac: allow configuring lower pbl values Andreas Färber <afaerber@suse.de> - 2016-12-08 15:10 +0100
      Re: [PATCH v3 6/6] net: smmac: allow configuring lower pbl values David Miller <davem@davemloft.net> - 2016-12-08 16:20 +0100
  [PATCH v3 1/6] net: stmmac: return error if no DMA configuration is found Niklas Cassel <niklas.cassel@axis.com> - 2016-12-07 15:30 +0100
    Re: [PATCH v3 1/6] net: stmmac: return error if no DMA configuration  is found Alexandre Torgue <alexandre.torgue@st.com> - 2016-12-08 11:50 +0100
      Re: [PATCH v3 1/6] net: stmmac: return error if no DMA  configuration is found David Miller <davem@davemloft.net> - 2016-12-08 16:20 +0100
        Re: [PATCH v3 1/6] net: stmmac: return error if no DMA configuration  is found Alexandre Torgue <alexandre.torgue@st.com> - 2016-12-08 16:50 +0100
  [PATCH v3 2/6] net: stmmac: simplify the common DMA init API Niklas Cassel <niklas.cassel@axis.com> - 2016-12-07 15:30 +0100
    Re: [PATCH v3 2/6] net: stmmac: simplify the common DMA init API Alexandre Torgue <alexandre.torgue@st.com> - 2016-12-08 10:00 +0100
  [PATCH v3 5/6] net: stmmac: add support for independent DMA pbl for tx/rx Niklas Cassel <niklas.cassel@axis.com> - 2016-12-07 15:30 +0100
    Re: [PATCH v3 5/6] net: stmmac: add support for independent DMA pbl  for tx/rx Alexandre Torgue <alexandre.torgue@st.com> - 2016-12-08 11:40 +0100
  [PATCH v3 4/6] net: stmmac: dwmac1000: fix define DMA_BUS_MODE_RPBL_MASK Niklas Cassel <niklas.cassel@axis.com> - 2016-12-07 15:30 +0100
    Re: [PATCH v3 4/6] net: stmmac: dwmac1000: fix define  DMA_BUS_MODE_RPBL_MASK Alexandre Torgue <alexandre.torgue@st.com> - 2016-12-08 10:20 +0100
  Re: [PATCH v3 0/6] net: stmmac: make DMA programmable burst length  more configurable David Miller <davem@davemloft.net> - 2016-12-08 19:10 +0100

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