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Date:   Fri, 22 May 2020 12:36:34 +0100
From:   Mark Brown <broonie@kernel.org>
To:     dillon.minfei@gmail.com
Cc:     robh+dt@kernel.org, p.zabel@pengutronix.de,
        mcoquelin.stm32@gmail.com, devicetree@vger.kernel.org,
        alexandre.torgue@st.com, thierry.reding@gmail.com,
        sam@ravnborg.org, airlied@linux.ie, daniel@ffwll.ch,
        mturquette@baylibre.com, sboyd@kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-spi@vger.kernel.org,
        linux-stm32@st-md-mailman.stormreply.com,
        dri-devel@lists.freedesktop.org, linux-clk@vger.kernel.org
Subject: Re: [PATCH v4 3/8] spi: stm32: Add 'SPI_SIMPLEX_RX', 'SPI_3WIRE_RX'
 support for stm32f4
Message-ID: <20200522113634.GE5801@sirena.org.uk>
References: <1589800165-3271-1-git-send-email-dillon.minfei@gmail.com>
 <1589800165-3271-4-git-send-email-dillon.minfei@gmail.com>
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On Mon, May 18, 2020 at 07:09:20PM +0800, dillon.minfei@gmail.com wrote:

> 2, use stm32 spi's "In full-duplex (BIDIMODE=0 and RXONLY=0)", as tx_buf is
> null, we must add dummy data sent out before read data.
> so, add stm32f4_spi_tx_dummy() to handle this situation.

There are flags SPI_CONTROLLER_MUST_TX and SPI_CONTROLLER_MUST_RX flags
that the driver can set if it needs to, no need to open code this in the
driver.

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