[U-Boot] [PATCH] FEC: Rework RX buffer init

[Marek Vasut]

Rework the RX buffer init so that it's easier to understand.
Firstly, allocate the whole RX buffer as one large continuous
piece of memory. Also, drop all these writel() accessors used
on the FEC RX DMA descriptor, since it's all flat bogus.

Finally, this makes recoverable stalls of the FEC on i.MX28
disappear completely.

Also, it removes whole 80 bytes from the size of u-boot!
(Tested with Debian GCC 4.7.1-3)

Signed-off-by: Marek Vasut <marex at denx.de>
Cc: Fabio Estevam <festevam at gmail.com>
Cc: Joe Hershberger <joe.hershberger at ni.com>
Cc: Otavio Salvador <otavio at ossystems.com.br>
Cc: Stefano Babic <sbabic at denx.de>
---
 drivers/net/fec_mxc.c |   47 ++++++++++++++++++++---------------------------
 1 file changed, 20 insertions(+), 27 deletions(-)

diff --git a/drivers/net/fec_mxc.c b/drivers/net/fec_mxc.c
index 3e232c7..1897397 100644
--- a/drivers/net/fec_mxc.c
+++ b/drivers/net/fec_mxc.c
@@ -289,43 +289,36 @@ static int fec_tx_task_disable(struct fec_priv *fec)
  */
 static int fec_rbd_init(struct fec_priv *fec, int count, int dsize)
 {
+	struct fec_bd *rbd = fec->rbd_base;
 	uint32_t size;
+	void *mem;
 	int i;
 
-	/*
-	 * Allocate memory for the buffers. This allocation respects the
-	 * alignment
-	 */
-	size = roundup(dsize, ARCH_DMA_MINALIGN);
+	if (!rbd->data_pointer) {
+		/*
+		 * Allocate memory for the buffers. This allocation
+		 * respects the alignment.
+		 */
+		size = roundup(dsize, ARCH_DMA_MINALIGN);
+		mem = memalign(ARCH_DMA_MINALIGN, size * count);
+		if (!mem)
+			return -ENOMEM;
+
+		for (i = 0; i < count; i++)
+			rbd[i].data_pointer = (uint32_t)(mem + size * i);
+	}
+
 	for (i = 0; i < count; i++) {
-		uint32_t data_ptr = readl(&fec->rbd_base[i].data_pointer);
-		if (data_ptr == 0) {
-			uint8_t *data = memalign(ARCH_DMA_MINALIGN,
-						 size);
-			if (!data) {
-				printf("%s: error allocating rxbuf %d\n",
-				       __func__, i);
-				goto err;
-			}
-			writel((uint32_t)data, &fec->rbd_base[i].data_pointer);
-		} /* needs allocation */
-		writew(FEC_RBD_EMPTY, &fec->rbd_base[i].status);
-		writew(0, &fec->rbd_base[i].data_length);
+		fec->rbd_base[i].status = FEC_RBD_EMPTY;
+		fec->rbd_base[i].data_length = 0;
 	}
 
 	/* Mark the last RBD to close the ring. */
-	writew(FEC_RBD_WRAP | FEC_RBD_EMPTY, &fec->rbd_base[i - 1].status);
+	fec->rbd_base[count - 1].status |= FEC_RBD_WRAP;
+
 	fec->rbd_index = 0;
 
 	return 0;
-
-err:
-	for (; i >= 0; i--) {
-		uint32_t data_ptr = readl(&fec->rbd_base[i].data_pointer);
-		free((void *)data_ptr);
-	}
-
-	return -ENOMEM;
 }
 
 /**
-- 
1.7.10.4