Re: [PATCH net] net: mvneta: set real interrupt per packet for tx_done

[David Miller]

From: Marcin Wojtas <mw@xxxxxxxxxxxx>
Date: Wed,  6 Jul 2016 04:18:58 +0200

> From: Dmitri Epshtein <dima@xxxxxxxxxxx>
> 
> Commit aebea2ba0f74 ("net: mvneta: fix Tx interrupt delay") intended to
> set coalescing threshold to a value guaranteeing interrupt generation
> per each sent packet, so that buffers can be released with no delay.
> 
> In fact setting threshold to '1' was wrong, because it causes interrupt
> every two packets. According to the documentation a reason behind it is
> following - interrupt occurs once sent buffers counter reaches a value,
> which is higher than one specified in MVNETA_TXQ_SIZE_REG(q). This
> behavior was confirmed during tests. Also when testing the SoC working
> as a NAS device, better performance was observed with int-per-packet,
> as it strongly depends on the fact that all transmitted packets are
> released immediately.
> 
> This commit enables NETA controller work in interrupt per sent packet mode
> by setting coalescing threshold to 0.
> 
> Signed-off-by: Dmitri Epshtein <dima@xxxxxxxxxxx>
> Signed-off-by: Marcin Wojtas <mw@xxxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # v3.10+
> Fixes aebea2ba0f74 ("net: mvneta: fix Tx interrupt delay")

Applied, thanks.