linux-kernel - [PATCH] dmaengine: stm32-mdma: initialize m2m_hw

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Message-ID: <20251030-mdma_warnings_fix-v1-1-987f67c75794@foss.st.com>
Date: Thu, 30 Oct 2025 13:26:38 +0100
From: Amelie Delaunay <amelie.delaunay@...s.st.com>
To: Vinod Koul <vkoul@...nel.org>,
        Maxime Coquelin
	<mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Clément Le Goffic <legoffic.clement@...il.com>
CC: <dmaengine@...r.kernel.org>, <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        Clément Le Goffic <clement.legoffic@...s.st.com>,
        "Amelie
 Delaunay" <amelie.delaunay@...s.st.com>
Subject: [PATCH] dmaengine: stm32-mdma: initialize m2m_hw_period and ccr to
 fix warnings

From: Clément Le Goffic <clement.legoffic@...s.st.com>

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 <clement.legoffic@...s.st.com>
Signed-off-by: Amelie Delaunay <amelie.delaunay@...s.st.com>
---
 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: 398035178503bf662281bbffb4bebce1460a4bc5
change-id: 20251030-mdma_warnings_fix-df4b3d1405ed

Best regards,
-- 
Amelie Delaunay <amelie.delaunay@...s.st.com>