Messages in this thread Patch in this message | | | From | Mathieu Poirier <> | Subject | [stable 4.19][PATCH 17/17] dmaengine: stm32-dma: check whether length is aligned on FIFO threshold | Date | Thu, 28 Nov 2019 09:50:02 -0700 |
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From: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
commit cc832dc8e32785a730ba07c3a357e17c201a5df8 upstream
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@st.com> Signed-off-by: Vinod Koul <vkoul@kernel.org> Cc: stable <stable@vger.kernel.org> # 4.19 Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> --- 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, -- 2.17.1
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