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 <pierre-yves.mordret@xxxxxx>
---
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,
--
2.7.4
