[U-Boot] [PATCH v4] net: fec_mxc: Poll FEC_TBD_READY after polling TDAR

[Fabio Estevam]

When testing the FEC driver on a mx6solox we noticed that the TDAR bit gets
always cleared prior then the READY bit is set in the last BD, which causes
FEC transmission to fail.

As explained by Ye Li:

"The TDAR bit is set when the descriptors are all out from TX ring, but the
descriptor properly is in transmitting not READY. These are two signals, and in
Ic simulation, we found the TDAR always clear prior than the READY bit of last
BD. In mx6solox, we use a latest version of FEC IP. It looks the intrinsic 
behave of TDAR bit is changed in this FEC version, not any bug in mx6sx."

Fix this by polling the READY bit of BD after the TDAR polling, which covers the
mx6solox case and does not harm for the other SoCs.

Signed-off-by: Fabio Estevam <fabio.estevam at freescale.com>
---
Changes since v3:
- Place invalidate_dcache_range in the correct location 
Changes since v2:
- Poll FEC_TBD_READY after polling TDAR

Signed-off-by: Fabio Estevam <fabio.estevam at freescale.com>
---
 drivers/net/fec_mxc.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/net/fec_mxc.c b/drivers/net/fec_mxc.c
index 4cefda4..675d53c 100644
--- a/drivers/net/fec_mxc.c
+++ b/drivers/net/fec_mxc.c
@@ -711,13 +711,22 @@ static int fec_send(struct eth_device *dev, void *packet, int length)
 			break;
 	}
 
-	if (!timeout)
+	if (!timeout) {
 		ret = -EINVAL;
+		goto out;
+	}
 
-	invalidate_dcache_range(addr, addr + size);
-	if (readw(&fec->tbd_base[fec->tbd_index].status) & FEC_TBD_READY)
+	timeout = FEC_XFER_TIMEOUT;
+	while (--timeout) {
+		invalidate_dcache_range(addr, addr + size);
+		if (!(readw(&fec->tbd_base[fec->tbd_index].status) & FEC_TBD_READY))
+			break;
+	}
+
+	if (!timeout)
 		ret = -EINVAL;
 
+out:
 	debug("fec_send: status 0x%x index %d ret %i\n",
 			readw(&fec->tbd_base[fec->tbd_index].status),
 			fec->tbd_index, ret);
-- 
1.9.1