Thread (2 messages) 2 messages, 2 authors, 2025-12-23
STALE206d REVIEWED: 1 (1M)

[PATCH v2] dmaengine: stm32-mdma: initialize m2m_hw_period and ccr to fix warnings

From: Amelie Delaunay <amelie.delaunay@foss.st.com>
Date: 2025-12-17 08:15:38
Also in: dmaengine, lkml
Subsystem: dma generic offload engine subsystem, stm32 dma drivers, the rest · Maintainers: Vinod Koul, Amélie Delaunay, Linus Torvalds

From: Clément Le Goffic <redacted>

m2m_hw_period is initialized only when chan_config->m2m_hw is true. This
triggers a warning:
‘m2m_hw_period’ may be used uninitialized [-Wmaybe-uninitialized]
Although m2m_hw_period is only used when chan_config->m2m_hw is true and
ignored otherwise, initialize it unconditionally to 0.

ccr is initialized by stm32_mdma_set_xfer_param() when the sg list is not
empty. This triggers a warning:
‘ccr’ may be used uninitialized [-Wmaybe-uninitialized]
Indeed, it could be used uninitialized if the sg list is empty. Initialize
it to 0.

Signed-off-by: Clément Le Goffic <redacted>
Reviewed-by: Clément Le Goffic <legoffic.clement@gmail.com>
Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
---
Changes in v2:
- Added code-review trailer
- Rebased on top of v6.19-rc1 
- Link to v1: https://lore.kernel.org/r/20251030-mdma_warnings_fix-v1-1-987f67c75794@foss.st.com (local)
---
 drivers/dma/stm32/stm32-mdma.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/dma/stm32/stm32-mdma.c b/drivers/dma/stm32/stm32-mdma.c
index 080c1c725216..b87d41b234df 100644
--- a/drivers/dma/stm32/stm32-mdma.c
+++ b/drivers/dma/stm32/stm32-mdma.c
@@ -731,7 +731,7 @@ static int stm32_mdma_setup_xfer(struct stm32_mdma_chan *chan,
 	struct stm32_mdma_chan_config *chan_config = &chan->chan_config;
 	struct scatterlist *sg;
 	dma_addr_t src_addr, dst_addr;
-	u32 m2m_hw_period, ccr, ctcr, ctbr;
+	u32 m2m_hw_period = 0, ccr = 0, ctcr, ctbr;
 	int i, ret = 0;
 
 	if (chan_config->m2m_hw)
---
base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
change-id: 20251030-mdma_warnings_fix-df4b3d1405ed

Best regards,
-- 
Amelie Delaunay [off-list ref]

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