[02/15] net: sun8i_emac: Don't hand out TX descriptor too early

Message ID 20200706004046.20842-3-andre.przywara@arm.com
State Accepted
Commit c35380c756a607f857b57aaaf93c53648ca10e9e
Headers show
Series
  • net: sun8i-emac fixes and cleanups
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Commit Message

Andre Przywara July 6, 2020, 12:40 a.m.
When initialising the TX DMA descriptors, we mostly chain them up,
but of course don't know about any data or its length yet.
That means they are still invalid, and the OWN bit should NOT be set
yet.

In fact when we later tell the MAC about the beginning of the chain,
and enable TX DMA in the start() routine, the MAC will start fetching
TX descriptors prematurely, as it can be seen by dumping the TX_DMA_STA
and TX_DMA_CUR_DESC registers.

Clear the owner bit, to not give the MAC the wrong illusion that it
owns the descriptors already.

Signed-off-by: Andre Przywara <andre.przywara at arm.com>
---
 drivers/net/sun8i_emac.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

diff --git a/drivers/net/sun8i_emac.c b/drivers/net/sun8i_emac.c
index d6685e00dc..22163f9405 100644
--- a/drivers/net/sun8i_emac.c
+++ b/drivers/net/sun8i_emac.c
@@ -415,7 +415,7 @@  static void tx_descs_init(struct emac_eth_dev *priv)
 		desc_p->buf_addr = (uintptr_t)&txbuffs[idx * CONFIG_ETH_BUFSIZE]
 			;
 		desc_p->next = (uintptr_t)&desc_table_p[idx + 1];
-		desc_p->status = (1 << 31);
+		desc_p->status = 0;
 		desc_p->st = 0;
 	}