[PATCH net-next 1/1] net: stmmac: xgmac: Fix L3L4 filter count

[Rohan G Thomas <rohan.g.thomas@intel.com>]

Get the exact count of L3L4 filters when the L3L4FNUM field of
HW_FEATURE1 register is >= 8. If L3L4FNUM < 8, then the number of L3L4
filters supported by XGMAC is equal to L3L4FNUM. From L3L4FNUM >= 8
the number of L3L4 filters goes on like 8, 16, 32, ... Current
maximum of L3L4FNUM = 10.

Also, fix the XGMAC_IDDR bitmask of L3L4_ADDR_CTRL register. IDDR
field starts from the 8th bit of the L3L4_ADDR_CTRL register. IDDR[3:0]
indicates the type of L3L4 filter register while IDDR[8:4] indicates
the filter number (0 to 31). So overall 9 bits are used for IDDR
(i.e. L3L4_ADDR_CTRL[16:8]) to address the registers of all the
filters. Currently, XGMAC_IDDR is GENMASK(15,8), causing issues
accessing L3L4 filters above 15 for those XGMACs configured with more
than 16 L3L4 filters.

Signed-off-by: Rohan G Thomas <rohan.g.thomas@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h     |  2 +-
 drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c | 10 ++++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h
index 1913385df685..153321fe42c3 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h
+++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h
@@ -165,7 +165,7 @@
 #define XGMAC_DCS_SHIFT			16
 #define XGMAC_ADDRx_LOW(x)		(0x00000304 + (x) * 0x8)
 #define XGMAC_L3L4_ADDR_CTRL		0x00000c00
-#define XGMAC_IDDR			GENMASK(15, 8)
+#define XGMAC_IDDR			GENMASK(16, 8)
 #define XGMAC_IDDR_SHIFT		8
 #define XGMAC_IDDR_FNUM			4
 #define XGMAC_TT			BIT(1)
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
index 070bd912580b..df5af52fd1a1 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
@@ -408,6 +408,16 @@ static int dwxgmac2_get_hw_feature(void __iomem *ioaddr,
 	/* MAC HW feature 1 */
 	hw_cap = readl(ioaddr + XGMAC_HW_FEATURE1);
 	dma_cap->l3l4fnum = (hw_cap & XGMAC_HWFEAT_L3L4FNUM) >> 27;
+	/* If L3L4FNUM < 8, then the number of L3L4 filters supported by
+	 * XGMAC is equal to L3L4FNUM. From L3L4FNUM >= 8 the number of
+	 * L3L4 filters goes on like 8, 16, 32, ... Current maximum of
+	 * L3L4FNUM = 10.
+	 */
+	if (dma_cap->l3l4fnum >= 8 && dma_cap->l3l4fnum <= 10)
+		dma_cap->l3l4fnum = 8 << (dma_cap->l3l4fnum - 8);
+	else if (dma_cap->l3l4fnum > 10)
+		dma_cap->l3l4fnum = 32;
+
 	dma_cap->hash_tb_sz = (hw_cap & XGMAC_HWFEAT_HASHTBLSZ) >> 24;
 	dma_cap->rssen = (hw_cap & XGMAC_HWFEAT_RSSEN) >> 20;
 	dma_cap->tsoen = (hw_cap & XGMAC_HWFEAT_TSOEN) >> 18;
-- 
2.26.2