From: Roman Guskov rguskov@dh-electronics.com
commit a590370d918fc66c62df6620445791fbe840344a upstream.
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 rguskov@dh-electronics.com Fixes: dcbe0d84dfa5 ("spi: add driver for STM32 SPI controller") Reviewed-by: Marek Vasut marex@denx.de Link: https://lore.kernel.org/r/20201221123532.27272-1-rguskov@dh-electronics.com Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/spi/spi-stm32.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/spi/spi-stm32.c +++ b/drivers/spi/spi-stm32.c @@ -299,9 +299,9 @@ static u32 stm32_spi_prepare_fthlv(struc
/* 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;
return fthlv; }