diff options
| author | Amelie Delaunay | 2022-10-24 10:36:11 +0200 |
|---|---|---|
| committer | Vinod Koul | 2022-11-08 10:43:56 +0530 |
| commit | 140fd5e74a1cc7413df88c735fff5ec64d33c1d3 (patch) | |
| tree | 593e0d646927c5a4f89afdfc8ea00bbd176b97dc /drivers/dma | |
| parent | ac2b9f34f02052709aea7b34bb2a165e1853eb41 (diff) | |
dmaengine: stm32-dma: fix potential race between pause and resume
When disabling dma channel, a TCF flag is set and as TCIE is enabled, an
interrupt is raised.
On a busy system, the interrupt may have latency and the user can ask for
dmaengine_resume while stm32-dma driver has not yet managed the complete
pause (backup of registers to restore state in resume).
To avoid such a case, instead of waiting the interrupt to backup the
registers, do it just after disabling the channel and discard Transfer
Complete interrupt in case the channel is paused.
Fixes: 099a9a94be0e ("dmaengine: stm32-dma: add device_pause/device_resume support")
Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Link: https://lore.kernel.org/r/20221024083611.132588-1-amelie.delaunay@foss.st.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Diffstat (limited to 'drivers/dma')
| -rw-r--r-- | drivers/dma/stm32-dma.c | 14 |
1 files changed, 6 insertions, 8 deletions
diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c index 4891a1767e5a..37674029cb42 100644 --- a/drivers/dma/stm32-dma.c +++ b/drivers/dma/stm32-dma.c @@ -675,6 +675,8 @@ static void stm32_dma_handle_chan_paused(struct stm32_dma_chan *chan) chan->chan_reg.dma_sndtr = stm32_dma_read(dmadev, STM32_DMA_SNDTR(chan->id)); + chan->status = DMA_PAUSED; + dev_dbg(chan2dev(chan), "vchan %pK: paused\n", &chan->vchan); } @@ -789,9 +791,7 @@ static irqreturn_t stm32_dma_chan_irq(int irq, void *devid) if (status & STM32_DMA_TCI) { stm32_dma_irq_clear(chan, STM32_DMA_TCI); if (scr & STM32_DMA_SCR_TCIE) { - if (chan->status == DMA_PAUSED && !(scr & STM32_DMA_SCR_EN)) - stm32_dma_handle_chan_paused(chan); - else + if (chan->status != DMA_PAUSED) stm32_dma_handle_chan_done(chan, scr); } status &= ~STM32_DMA_TCI; @@ -838,13 +838,11 @@ static int stm32_dma_pause(struct dma_chan *c) return -EPERM; spin_lock_irqsave(&chan->vchan.lock, flags); + ret = stm32_dma_disable_chan(chan); - /* - * A transfer complete flag is set to indicate the end of transfer due to the stream - * interruption, so wait for interrupt - */ if (!ret) - chan->status = DMA_PAUSED; + stm32_dma_handle_chan_paused(chan); + spin_unlock_irqrestore(&chan->vchan.lock, flags); return ret; |