6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Amelie Delaunay amelie.delaunay@foss.st.com
commit a4b306eb83579c07b63dc65cd5bae53b7b4019d0 upstream.
Current implementation relies on curr_hwdesc index. But to keep this index up to date, Block Transfer interrupt (BTIE) has to be enabled. If it is not, curr_hwdesc is not updated, and then residue is not reliable. Rely on Link Address Register instead. And disable BTIE interrupt in stm32_mdma_setup_xfer() because it is no more needed in case of _prep_slave_sg() to maintain curr_hwdesc up to date. It avoids extra interrupts and also ensures a reliable residue. These improvements are required for STM32 DCMI camera capture use case, which need STM32 DMA and MDMA chaining for good performance.
Fixes: 696874322771 ("dmaengine: stm32-mdma: add support to be triggered by STM32 DMA") Signed-off-by: Amelie Delaunay amelie.delaunay@foss.st.com Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20231004163531.2864160-2-amelie.delaunay@foss.st.c... Signed-off-by: Vinod Koul vkoul@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/dma/stm32-mdma.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-)
--- a/drivers/dma/stm32-mdma.c +++ b/drivers/dma/stm32-mdma.c @@ -778,8 +778,6 @@ static int stm32_mdma_setup_xfer(struct /* Enable interrupts */ ccr &= ~STM32_MDMA_CCR_IRQ_MASK; ccr |= STM32_MDMA_CCR_TEIE | STM32_MDMA_CCR_CTCIE; - if (sg_len > 1) - ccr |= STM32_MDMA_CCR_BTIE; desc->ccr = ccr;
return 0; @@ -1325,12 +1323,21 @@ static size_t stm32_mdma_desc_residue(st { struct stm32_mdma_device *dmadev = stm32_mdma_get_dev(chan); struct stm32_mdma_hwdesc *hwdesc; - u32 cbndtr, residue, modulo, burst_size; + u32 cisr, clar, cbndtr, residue, modulo, burst_size; int i;
+ cisr = stm32_mdma_read(dmadev, STM32_MDMA_CISR(chan->id)); + residue = 0; - for (i = curr_hwdesc + 1; i < desc->count; i++) { + /* Get the next hw descriptor to process from current transfer */ + clar = stm32_mdma_read(dmadev, STM32_MDMA_CLAR(chan->id)); + for (i = desc->count - 1; i >= 0; i--) { hwdesc = desc->node[i].hwdesc; + + if (hwdesc->clar == clar) + break;/* Current transfer found, stop cumulating */ + + /* Cumulate residue of unprocessed hw descriptors */ residue += STM32_MDMA_CBNDTR_BNDT(hwdesc->cbndtr); } cbndtr = stm32_mdma_read(dmadev, STM32_MDMA_CBNDTR(chan->id));