In case of MDMA chaining, DMA is configured in Double-Buffer Mode (DBM) with two periods, but if transfer has been prepared with _prep_slave_sg(), the transfer is not marked cyclic (=!chan->desc->cyclic). However, as DBM is activated for MDMA chaining, residue computation must take into account cyclic constraints.
With only two periods in MDMA chaining, and no update due to Transfer Complete interrupt masked, n_sg is always 0. If DMA current memory address (depending on SxCR.CT and SxM0AR/SxM1AR) does not correspond, it means n_sg should be increased. Then, the residue of the current period is the one read from SxNDTR and should not be overwritten with the full period length.
Fixes: 723795173ce1 ("dmaengine: stm32-dma: add support to trigger STM32 MDMA") Signed-off-by: Amelie Delaunay amelie.delaunay@foss.st.com Cc: stable@vger.kernel.org --- drivers/dma/stm32-dma.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c index 7427acc82259..0b30151fb45c 100644 --- a/drivers/dma/stm32-dma.c +++ b/drivers/dma/stm32-dma.c @@ -1389,11 +1389,12 @@ static size_t stm32_dma_desc_residue(struct stm32_dma_chan *chan,
residue = stm32_dma_get_remaining_bytes(chan);
- if (chan->desc->cyclic && !stm32_dma_is_current_sg(chan)) { + if ((chan->desc->cyclic || chan->trig_mdma) && !stm32_dma_is_current_sg(chan)) { n_sg++; if (n_sg == chan->desc->num_sgs) n_sg = 0; - residue = sg_req->len; + if (!chan->trig_mdma) + residue = sg_req->len; }
/* @@ -1403,7 +1404,7 @@ static size_t stm32_dma_desc_residue(struct stm32_dma_chan *chan, * residue = remaining bytes from NDTR + remaining * periods/sg to be transferred */ - if (!chan->desc->cyclic || n_sg != 0) + if ((!chan->desc->cyclic && !chan->trig_mdma) || n_sg != 0) for (i = n_sg; i < desc->num_sgs; i++) residue += desc->sg_req[i].len;