From cc832dc8e32785a730ba07c3a357e17c201a5df8 Mon Sep 17 00:00:00 2001 From: Pierre-Yves MORDRET Date: Tue, 11 Sep 2018 09:31:16 +0200 Subject: [PATCH] dmaengine: stm32-dma: check whether length is aligned on FIFO threshold When a period length is not multiple of FIFO some data may be stuck within FIFO. Burst/FIFO Threshold/Period or buffer length check has to be hardened In any case DMA will grant any request from client but will degraded any parameters whether awkward. Signed-off-by: Pierre-Yves MORDRET Signed-off-by: Vinod Koul --- drivers/dma/stm32-dma.c | 20 ++++++-------------- 1 file changed, 6 insertions(+), 14 deletions(-) diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c index 379e8d534e61..4903a408fc14 100644 --- a/drivers/dma/stm32-dma.c +++ b/drivers/dma/stm32-dma.c @@ -308,20 +308,12 @@ static bool stm32_dma_fifo_threshold_is_allowed(u32 burst, u32 threshold, static bool stm32_dma_is_burst_possible(u32 buf_len, u32 threshold) { - switch (threshold) { - case STM32_DMA_FIFO_THRESHOLD_FULL: - if (buf_len >= STM32_DMA_MAX_BURST) - return true; - else - return false; - case STM32_DMA_FIFO_THRESHOLD_HALFFULL: - if (buf_len >= STM32_DMA_MAX_BURST / 2) - return true; - else - return false; - default: - return false; - } + /* + * Buffer or period length has to be aligned on FIFO depth. + * Otherwise bytes may be stuck within FIFO at buffer or period + * length. + */ + return ((buf_len % ((threshold + 1) * 4)) == 0); } static u32 stm32_dma_get_best_burst(u32 buf_len, u32 max_burst, u32 threshold,