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dmaengine: stm32-dma: fix max items per transfer

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Having 0 in item counter register is valid and stands for a "No or Ended
transfer". Therefore valid transfer starts from @+0 to @+0xFFFE leading to
unaligned scatter gather at boundary. Thus it's safer to round down this
value on its FIFO size (16 Bytes).

Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This commit is contained in:
Pierre Yves MORDRET 2018-03-13 17:42:04 +01:00 committed by Vinod Koul
parent c2d86b1cd6
commit 80a76952a5
1 changed files with 11 additions and 8 deletions
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19
drivers/dma/stm32-dma.c
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@ -38,10 +38,6 @@
#define STM32_DMA_TEI BIT(3) /* Transfer Error Interrupt */
#define STM32_DMA_DMEI BIT(2) /* Direct Mode Error Interrupt */
#define STM32_DMA_FEI BIT(0) /* FIFO Error Interrupt */
#define STM32_DMA_MASKI (STM32_DMA_TCI \
| STM32_DMA_TEI \
| STM32_DMA_DMEI \
| STM32_DMA_FEI)
/* DMA Stream x Configuration Register */
#define STM32_DMA_SCR(x) (0x0010 + 0x18 * (x)) /* x = 0..7 */
@ -118,6 +114,13 @@
#define STM32_DMA_FIFO_THRESHOLD_FULL 0x03
#define STM32_DMA_MAX_DATA_ITEMS 0xffff
/*
* Valid transfer starts from @0 to @0xFFFE leading to unaligned scatter
* gather at boundary. Thus it's safer to round down this value on FIFO
* size (16 Bytes)
*/
#define STM32_DMA_ALIGNED_MAX_DATA_ITEMS \
ALIGN_DOWN(STM32_DMA_MAX_DATA_ITEMS, 16)
#define STM32_DMA_MAX_CHANNELS 0x08
#define STM32_DMA_MAX_REQUEST_ID 0x08
#define STM32_DMA_MAX_DATA_PARAM 0x03
@ -869,7 +872,7 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_slave_sg(
desc->sg_req[i].len = sg_dma_len(sg);
nb_data_items = desc->sg_req[i].len / buswidth;
if (nb_data_items > STM32_DMA_MAX_DATA_ITEMS) {
if (nb_data_items > STM32_DMA_ALIGNED_MAX_DATA_ITEMS) {
dev_err(chan2dev(chan), "nb items not supported\n");
goto err;
}
@ -935,7 +938,7 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_dma_cyclic(
return NULL;
nb_data_items = period_len / buswidth;
if (nb_data_items > STM32_DMA_MAX_DATA_ITEMS) {
if (nb_data_items > STM32_DMA_ALIGNED_MAX_DATA_ITEMS) {
dev_err(chan2dev(chan), "number of items not supported\n");
return NULL;
}
@ -985,7 +988,7 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_dma_memcpy(
u32 num_sgs, best_burst, dma_burst, threshold;
int i;
num_sgs = DIV_ROUND_UP(len, STM32_DMA_MAX_DATA_ITEMS);
num_sgs = DIV_ROUND_UP(len, STM32_DMA_ALIGNED_MAX_DATA_ITEMS);
desc = stm32_dma_alloc_desc(num_sgs);
if (!desc)
return NULL;
@ -994,7 +997,7 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_dma_memcpy(
for (offset = 0, i = 0; offset < len; offset += xfer_count, i++) {
xfer_count = min_t(size_t, len - offset,
STM32_DMA_MAX_DATA_ITEMS);
STM32_DMA_ALIGNED_MAX_DATA_ITEMS);
/* Compute best burst size */
max_width = DMA_SLAVE_BUSWIDTH_1_BYTE;