linux-kernel - [PATCH 15/18] spi: stm32: fix stm32_spi_prepare_mbr in case of odd clk

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Date:   Wed, 5 Aug 2020 09:02:10 +0200
From:   Alain Volmat <alain.volmat@...com>
To:     <broonie@...nel.org>, <amelie.delaunay@...com>
CC:     <mcoquelin.stm32@...il.com>, <alexandre.torgue@...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@...com>,
        <alain.volmat@...com>
Subject: [PATCH 15/18] spi: stm32: fix stm32_spi_prepare_mbr in case of odd clk_rate

From: Amelie Delaunay <amelie.delaunay@...com>

Fix spi->clk_rate when it is odd to the nearest lowest even value because
minimum SPI divider is 2.

Signed-off-by: Amelie Delaunay <amelie.delaunay@...com>
Signed-off-by: Alain Volmat <alain.volmat@...com>
---
 drivers/spi/spi-stm32.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
index 0aec32538093..2665d8d7f318 100644
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -436,7 +436,8 @@ static int stm32_spi_prepare_mbr(struct stm32_spi *spi, u32 speed_hz,
 {
 	u32 div, mbrdiv;
 
-	div = DIV_ROUND_UP(spi->clk_rate, speed_hz);
+	/* Ensure spi->clk_rate is even */
+	div = DIV_ROUND_UP(spi->clk_rate & ~0x1, speed_hz);
 
 	/*
 	 * SPI framework set xfer->speed_hz to master->max_speed_hz if
-- 
2.7.4