4.4-stable review patch. If anyone has any objections, please let me know.
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From: Masaru Nagai masaru.nagai.vx@renesas.com
[ Upstream commit ae9819e339b451da7a86ab6fe38ecfcb6814e78a ]
Hardware has the CBS (Credit Based Shaper) which affects only Q3 and Q2. When updating the CBS settings, even if the driver does so after waiting for Tx DMA finished, there is a possibility that frame data still remains in TxFIFO.
To avoid this, decrease TxFIFO depth of Q3 and Q2 to one.
This patch has been exercised this using netperf TCP_MAERTS, TCP_STREAM and UDP_STREAM tests run on an Ebisu board. No performance change was detected, outside of noise in the tests, both in terms of throughput and CPU utilisation.
Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper") Signed-off-by: Masaru Nagai masaru.nagai.vx@renesas.com Signed-off-by: Kazuya Mizuguchi kazuya.mizuguchi.ks@renesas.com [simon: updated changelog] Signed-off-by: Simon Horman horms+renesas@verge.net.au Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/ethernet/renesas/ravb_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/net/ethernet/renesas/ravb_main.c +++ b/drivers/net/ethernet/renesas/ravb_main.c @@ -453,7 +453,7 @@ static int ravb_dmac_init(struct net_dev ravb_write(ndev, RCR_EFFS | RCR_ENCF | RCR_ETS0 | 0x18000000, RCR);
/* Set FIFO size */ - ravb_write(ndev, TGC_TQP_AVBMODE1 | 0x00222200, TGC); + ravb_write(ndev, TGC_TQP_AVBMODE1 | 0x00112200, TGC);
/* Timestamp enable */ ravb_write(ndev, TCCR_TFEN, TCCR);