From a590370d918fc66c62df6620445791fbe840344a Mon Sep 17 00:00:00 2001 From: Roman Guskov Date: Mon, 21 Dec 2020 13:35:32 +0100 Subject: [PATCH] spi: stm32: FIFO threshold level - fix align packet size if cur_bpw <= 8 and xfer_len < 4 then the value of fthlv will be 1 and SPI registers content may have been lost. * If SPI data register is accessed as a 16-bit register and DSIZE <= 8bit, better to select FTHLV = 2, 4, 6 etc * If SPI data register is accessed as a 32-bit register and DSIZE > 8bit, better to select FTHLV = 2, 4, 6 etc, while if DSIZE <= 8bit, better to select FTHLV = 4, 8, 12 etc Signed-off-by: Roman Guskov Fixes: dcbe0d84dfa5 ("spi: add driver for STM32 SPI controller") Reviewed-by: Marek Vasut Link: https://lore.kernel.org/r/20201221123532.27272-1-rguskov@dh-electronics.com Signed-off-by: Mark Brown --- drivers/spi/spi-stm32.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c index 471dedf3d339..6017209c6d2f 100644 --- a/drivers/spi/spi-stm32.c +++ b/drivers/spi/spi-stm32.c @@ -493,9 +493,9 @@ static u32 stm32h7_spi_prepare_fthlv(struct stm32_spi *spi, u32 xfer_len) /* align packet size with data registers access */ if (spi->cur_bpw > 8) - fthlv -= (fthlv % 2); /* multiple of 2 */ + fthlv += (fthlv % 2) ? 1 : 0; else - fthlv -= (fthlv % 4); /* multiple of 4 */ + fthlv += (fthlv % 4) ? (4 - (fthlv % 4)) : 0; if (!fthlv) fthlv = 1;