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From:   dillon min <dillon.minfei@gmail.com>
Date:   Fri, 22 May 2020 22:57:10 +0800
Message-ID: <CAL9mu0LAnT+AfjpGs0O-MD2HYrpnQRmrj6qXtJQrJi9kbQLPUw@mail.gmail.com>
Subject: Re: [PATCH v4 3/8] spi: stm32: Add 'SPI_SIMPLEX_RX', 'SPI_3WIRE_RX'
 support for stm32f4
To:     Mark Brown <broonie@kernel.org>
Cc:     Rob Herring <robh+dt@kernel.org>, p.zabel@pengutronix.de,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        Alexandre Torgue <alexandre.torgue@st.com>,
        thierry.reding@gmail.com, Sam Ravnborg <sam@ravnborg.org>,
        Dave Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org,
        linux-stm32@st-md-mailman.stormreply.com,
        "open list:DRM PANEL DRIVERS" <dri-devel@lists.freedesktop.org>,
        linux-clk <linux-clk@vger.kernel.org>
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hi Mark,

Thanks for reviewing.

On Fri, May 22, 2020 at 7:36 PM Mark Brown <broonie@kernel.org> wrote:
>
> 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.

Yes, after check SPI_CONTROLLER_MUST_TX in drivers/spi/spi.c , it's
indeed to meet
this situation,  i will try it and sumbmit a new patch.

thanks.

best regards

Dillon