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Date:   Mon, 19 Aug 2019 02:43:54 +0200
From:   Andrew Lunn <andrew@lunn.ch>
To:     Vladimir Oltean <olteanv@gmail.com>
Cc:     Mark Brown <broonie@kernel.org>,
        Hubert Feurstein <h.feurstein@gmail.com>, mlichvar@redhat.com,
        Richard Cochran <richardcochran@gmail.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        linux-spi@vger.kernel.org, netdev <netdev@vger.kernel.org>
Subject: Re: [RFC PATCH net-next 03/11] spi: Add a PTP system timestamp to
 the transfer structure
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> MDIO bus controllers are in a similar situation (with Hubert's patch)
> but at least there the frame size is fixed and I haven't heard of an
> MDIO controller to use DMA.

Linux does not have any DMA driver MDIO busses, as far as i know. It
does not make sense, since you are only transferring 16bits of
data. The vast majority are polled completion, but there is one which
generates an interrupt on completion.

	Andrew