diff mbox series

[06/15] net: sun8i_emac: Improve cache maintenance on RX descriptor init

Message ID 20200706004046.20842-7-andre.przywara@arm.com
State Accepted
Commit 69853123c513cf478992ca44e8a39afd651811a9
Delegated to: Jagannadha Sutradharudu Teki
Headers show
Series net: sun8i-emac fixes and cleanups | expand

Commit Message

André Przywara July 6, 2020, 12:40 a.m. UTC
Before we initialise the RX descriptors, there is no need to *clean*
them from the cache, as we touch them for the first time.
However we should cover the case that those buffers contain dirty cache
lines, which could be evicted and written back to DRAM any time later,
in the worst case *after* the MAC has transferred a packet into them.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/net/sun8i_emac.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/sun8i_emac.c b/drivers/net/sun8i_emac.c
index 1eafb66698..44ec8f3a63 100644
--- a/drivers/net/sun8i_emac.c
+++ b/drivers/net/sun8i_emac.c
@@ -383,16 +383,21 @@  static void rx_descs_init(struct emac_eth_dev *priv)
 	struct emac_dma_desc *desc_p;
 	u32 idx;
 
-	/* flush Rx buffers */
-	flush_dcache_range((uintptr_t)rxbuffs, (ulong)rxbuffs +
-			RX_TOTAL_BUFSIZE);
+	/*
+	 * Make sure we don't have dirty cache lines around, which could
+	 * be cleaned to DRAM *after* the MAC has already written data to it.
+	 */
+	invalidate_dcache_range((uintptr_t)desc_table_p,
+			      (uintptr_t)desc_table_p + sizeof(priv->rx_chain));
+	invalidate_dcache_range((uintptr_t)rxbuffs,
+				(uintptr_t)rxbuffs + sizeof(priv->rxbuffer));
 
 	for (idx = 0; idx < CONFIG_RX_DESCR_NUM; idx++) {
 		desc_p = &desc_table_p[idx];
 		desc_p->buf_addr = (uintptr_t)&rxbuffs[idx * CONFIG_ETH_BUFSIZE]
 			;
 		desc_p->next = (uintptr_t)&desc_table_p[idx + 1];
-		desc_p->ctl_size |= CONFIG_ETH_RXSIZE;
+		desc_p->ctl_size = CONFIG_ETH_RXSIZE;
 		desc_p->status = EMAC_DESC_OWN_DMA;
 	}