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

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Message-ID: <287da4e3-0a28-42a3-8f59-7e41dde4d20c@gmail.com>
Date: Thu, 30 Oct 2025 14:09:38 +0100
From: Clément Le Goffic <legoffic.clement@...il.com>
To: Amelie Delaunay <amelie.delaunay@...s.st.com>,
 Vinod Koul <vkoul@...nel.org>, Maxime Coquelin <mcoquelin.stm32@...il.com>,
 Alexandre Torgue <alexandre.torgue@...s.st.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>
Subject: Re: [PATCH] dmaengine: stm32-mdma: initialize m2m_hw_period and ccr
 to fix warnings

On 10/30/25 13:26, Amelie Delaunay wrote:
> 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,

Hi Amélie,

Thank you for upstreaming this patch.
You can add my reviewed-by tag:

Reviewed-by: Clément Le Goffic <legoffic.clement@...il.com>

Best regards,
Clément