netdev - Re: [PATCH v3 net-next 4/8] net: mvneta: sync dma buffers before refilling hw queues

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Message-ID: <20191015160151.2d227995@cakuba.netronome.com>
Date:   Tue, 15 Oct 2019 16:01:51 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     Lorenzo Bianconi <lorenzo@...nel.org>
Cc:     netdev@...r.kernel.org, lorenzo.bianconi@...hat.com,
        davem@...emloft.net, thomas.petazzoni@...tlin.com,
        brouer@...hat.com, ilias.apalodimas@...aro.org,
        matteo.croce@...hat.com, mw@...ihalf.com
Subject: Re: [PATCH v3 net-next 4/8] net: mvneta: sync dma buffers before
 refilling hw queues

On Mon, 14 Oct 2019 12:49:51 +0200, Lorenzo Bianconi wrote:
> mvneta driver can run on not cache coherent devices so it is
> necessary to sync DMA buffers before sending them to the device
> in order to avoid memory corruptions. Running perf analysis we can
> see a performance cost associated with this DMA-sync (anyway it is
> already there in the original driver code). In follow up patches we
> will add more logic to reduce DMA-sync as much as possible.
> 
> Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
> Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>

Should this not be squashed into patch 2? Isn't there a transient bug
otherwise?