From 9f0c21bac5a8089e74b21d007e26fb4594b10d73 Mon Sep 17 00:00:00 2001 From: Carlos Song Date: Mon, 17 Nov 2025 11:03:55 +0800 Subject: [PATCH] spi: spi-fsl-lpspi: fix watermark truncation caused by type cast 't->len' is an unsigned integer, while 'watermark' and 'txfifosize' are u8. Using min_t with typeof(watermark) forces both values to be cast to u8, which truncates len when it exceeds 255. For example, len = 4096 becomes 0 after casting, resulting in an incorrect watermark value. Use a wider type in min_t to avoid truncation and ensure the correct minimum value is applied. Fixes: a750050349ea ("spi: spi-fsl-lpspi: use min_t() to improve code") Signed-off-by: Carlos Song Reviewed-by: Daniel Baluta Link: https://patch.msgid.link/20251117030355.1359081-1-carlos.song@nxp.com Signed-off-by: Mark Brown --- drivers/spi/spi-fsl-lpspi.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/spi/spi-fsl-lpspi.c b/drivers/spi/spi-fsl-lpspi.c index 8da66e1013867..065456aba2aea 100644 --- a/drivers/spi/spi-fsl-lpspi.c +++ b/drivers/spi/spi-fsl-lpspi.c @@ -486,7 +486,13 @@ static int fsl_lpspi_setup_transfer(struct spi_controller *controller, fsl_lpspi->tx = fsl_lpspi_buf_tx_u32; } - fsl_lpspi->watermark = min_t(typeof(fsl_lpspi->watermark), + /* + * t->len is 'unsigned' and txfifosize and watermrk is 'u8', force + * type cast is inevitable. When len > 255, len will be truncated in min_t(), + * it caused wrong watermark set. 'unsigned int' is as the designated type + * for min_t() to avoid truncation. + */ + fsl_lpspi->watermark = min_t(unsigned int, fsl_lpspi->txfifosize, t->len); -- 2.47.3