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authorNathan Sullivan <nathan.sullivan@ni.com>2015-05-13 17:01:36 -0500
committerDavid S. Miller <davem@davemloft.net>2015-05-15 12:13:11 -0400
commit86b5e7de07aa1abc87ecc40d2aca6070348e4469 (patch)
treef82d533282c5f4038c172be1bad4c5ac24ea858e /drivers/net
parenteea39946a1f36e8a5a47c86e7ecfca6076868505 (diff)
net: macb: Add better comment for RXUBR handling
Describe the handler for RXUBR better with a new comment. Signed-off-by: Nathan Sullivan <nathan.sullivan@ni.com> Reviewied-by: Josh Cartwright <joshc@ni.com> Reviewied-by: Ben Shelton <ben.shelton@ni.com> Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/ethernet/cadence/macb.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
index 61aa570aad9a..5f10dfc631d7 100644
--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c
@@ -1037,6 +1037,12 @@ static irqreturn_t macb_interrupt(int irq, void *dev_id)
* add that if/when we get our hands on a full-blown MII PHY.
*/
+ /* There is a hardware issue under heavy load where DMA can
+ * stop, this causes endless "used buffer descriptor read"
+ * interrupts but it can be cleared by re-enabling RX. See
+ * the at91 manual, section 41.3.1 or the Zynq manual
+ * section 16.7.4 for details.
+ */
if (status & MACB_BIT(RXUBR)) {
ctrl = macb_readl(bp, NCR);
macb_writel(bp, NCR, ctrl & ~MACB_BIT(RE));