Describe the handler for RXUBR better with a new comment.
Signed-off-by: Nathan Sullivan <nathan.sulli...@ni.com>
Reviewied-by: Josh Cartwright <jo...@ni.com>
Reviewied-by: Ben Shelton <ben.shel...@ni.com>
---
drivers/net/ethernet/cadence/macb.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/net/ethernet/cadence/macb.c
b/drivers/net/ethernet/cadence/macb.c
index 61aa570..5f10dfc 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));
--
1.7.10.4
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