[v1,1/1] dmaengine: stm32-dma: check whether length is aligned on FIFO threshold
From: Pierre Yves MORDRET <hidden>
Date: 2018-09-11 07:31:46
Also in:
linux-arm-kernel, lkml
Subsystem:
dma generic offload engine subsystem, the rest · Maintainers:
Vinod Koul, Linus Torvalds
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 <redacted>
---
Version history:
v1:
* Initial
---
---
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 379e8d5..4903a40 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,