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From:   Alain Volmat <alain.volmat@st.com>
To:     <broonie@kernel.org>, <amelie.delaunay@st.com>
CC:     <mcoquelin.stm32@gmail.com>, <alexandre.torgue@st.com>,
        <linux-spi@vger.kernel.org>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <fabrice.gasnier@st.com>,
        <alain.volmat@st.com>
Subject: [PATCH 18/18] spi: stm32h7: ensure message are smaller than max size
Date:   Wed, 5 Aug 2020 09:02:13 +0200
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Ensure that messages given to transfer_one handler can actually be
handled by it. For that purpose rely on the SPI framework
spi_split_transfers_maxsize function to split messages whenever necessary.

Signed-off-by: Alain Volmat <alain.volmat@st.com>
---
 drivers/spi/spi-stm32.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
index b909afd9e99b..bd21b698af84 100644
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -1021,6 +1021,20 @@ static int stm32_spi_prepare_msg(struct spi_master *master,
 		spi_dev->mode & SPI_LSB_FIRST,
 		spi_dev->mode & SPI_CS_HIGH);
 
+	/* On STM32H7, messages should not exceed a maximum size setted
+	 * afterward via the set_number_of_data function. In order to
+	 * ensure that, split large messages into several messages
+	 */
+	if (spi->cfg->set_number_of_data) {
+		int ret;
+
+		ret = spi_split_transfers_maxsize(master, msg,
+						  STM32H7_SPI_TSIZE_MAX,
+						  GFP_KERNEL | GFP_DMA);
+		if (ret)
+			return ret;
+	}
+
 	spin_lock_irqsave(&spi->lock, flags);
 
 	/* CPOL, CPHA and LSB FIRST bits have common register */
-- 
2.7.4