From: Simon Horman <horms+renesas@xxxxxxxxxxxx>
Date: Thu, 7 Mar 2019 11:24:47 +0100
> From: Masaru Nagai <masaru.nagai.vx@xxxxxxxxxxx>
>
> 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@xxxxxxxxxxx>
> Signed-off-by: Kazuya Mizuguchi <kazuya.mizuguchi.ks@xxxxxxxxxxx>
> [simon: updated changelog]
> Signed-off-by: Simon Horman <horms+renesas@xxxxxxxxxxxx>
Applied and queued up for -stable, thanks.
