From: Nathan Sullivan <nathan.sullivan@ni.com> Date: Wed, 13 May 2015 22:01:36 +0000 (-0500) Subject: net: macb: Add better comment for RXUBR handling X-Git-Tag: firefly_0821_release~176^2~1737^2~29 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=86b5e7de07aa1abc87ecc40d2aca6070348e4469;p=firefly-linux-kernel-4.4.55.git 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> --- 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));