lkml.org 
[lkml]   [2019]   [Mar]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.4 131/230] ravb: Decrease TxFIFO depth of Q3 and Q2 to one
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    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);

    \
     
     \ /
      Last update: 2019-03-22 14:11    [W:4.104 / U:0.036 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site