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dmaengine: stm32-dma: check whether length is aligned on FIFO threshold

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commit cc832dc8e3 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>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Pierre-Yves MORDRET 2018-09-11 09:31:16 +02:00 committed by Greg Kroah-Hartman
parent f0b7d56f1f
commit ecda0abb14
1 changed files with 6 additions and 14 deletions
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20
drivers/dma/stm32-dma.c
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@ -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,