Program management descriptor's access mode according to the
dynamically detected CPU endianness.

Signed-off-by: Arun Chandran <[email protected]>
Acked-by: Nicolas Ferre <[email protected]>
Tested-by: Michal Simek <[email protected]>
---
* Adding CPU endianness detection according to Michal Simek
* Added Acked-by: Nicolas Ferre
* Added Tested-by: Michal Simek
---
---
 drivers/net/ethernet/cadence/macb.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb.c 
b/drivers/net/ethernet/cadence/macb.c
index 05fb36d..1fe8b94 100644
--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c
@@ -1578,6 +1578,7 @@ static u32 macb_dbw(struct macb *bp)
 static void macb_configure_dma(struct macb *bp)
 {
        u32 dmacfg;
+       u32 tmp, ncr;
 
        if (macb_is_gem(bp)) {
                dmacfg = gem_readl(bp, DMACFG) & ~GEM_BF(RXBS, -1L);
@@ -1586,10 +1587,23 @@ static void macb_configure_dma(struct macb *bp)
                        dmacfg = GEM_BFINS(FBLDO, bp->dma_burst_length, dmacfg);
                dmacfg |= GEM_BIT(TXPBMS) | GEM_BF(RXBMS, -1L);
                dmacfg &= ~GEM_BIT(ENDIA_PKT);
-               /* Tell the chip to byteswap descriptors on big-endian hosts */
-#ifdef __BIG_ENDIAN
-               dmacfg |= GEM_BIT(ENDIA_DESC);
-#endif
+
+               /* Find the CPU endianness by using the loopback bit of net_ctrl
+                * register. save it first. When the CPU is in big endian we
+                * need to program swaped mode for management descriptor access.
+                */
+               ncr = macb_readl(bp, NCR);
+               __raw_writel(MACB_BIT(LLB), bp->regs + MACB_NCR);
+               tmp =  __raw_readl(bp->regs + MACB_NCR);
+
+               if (tmp == MACB_BIT(LLB))
+                       dmacfg &= ~GEM_BIT(ENDIA_DESC);
+               else
+                       dmacfg |= GEM_BIT(ENDIA_DESC); /* CPU in big endian */
+
+               /* Restore net_ctrl */
+               macb_writel(bp, NCR, ncr);
+
                if (bp->dev->features & NETIF_F_HW_CSUM)
                        dmacfg |= GEM_BIT(TXCOEN);
                else
-- 
1.9.1

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