linux-kernel - [PATCH v2 4/8] spi: stm32h7: ensure message are smaller than max size

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Date:   Fri, 5 Feb 2021 19:59:28 +0100
From:   Alain Volmat <alain.volmat@...s.st.com>
To:     <broonie@...nel.org>, <amelie.delaunay@...s.st.com>
CC:     <mcoquelin.stm32@...il.com>, <alexandre.torgue@...s.st.com>,
        <linux-spi@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <fabrice.gasnier@...s.st.com>,
        <alain.volmat@...s.st.com>
Subject: [PATCH v2 4/8] spi: stm32h7: ensure message are smaller than max size

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@...s.st.com>
---
v2: reordered within the serie

 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 a46132e81533..8e4db219b95d 100644
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -1004,6 +1004,20 @@ 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 */
-- 
2.17.1