linux-kernel - Re: [PATCH] dmaengine: xilinx_dma: Fix uninitialized addr_width when "xlnx,addrwidth" property is missing

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Message-Id: <DCKRVLG0RDPF.2HIFAQSB8UF3H@folker-schwesinger.de>
Date: Fri, 05 Sep 2025 09:51:36 +0000
From: "Folker Schwesinger" <dev@...ker-schwesinger.de>
To: "Suraj Gupta" <suraj.gupta2@....com>, <vkoul@...nel.org>,
 <michal.simek@....com>, <radhey.shyam.pandey@....com>
Cc: <dmaengine@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
 <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] dmaengine: xilinx_dma: Fix uninitialized addr_width
 when "xlnx,addrwidth" property is missing

On Fri Sep 5, 2025 at 8:48 AM CEST, Suraj Gupta wrote:
> When device tree lacks optional "xlnx,addrwidth" property, the addr_width
> variable remained uninitialized with garbage values, causing incorrect
> DMA mask configuration and subsequent probe failure. The fix ensures a
> fallback to the default 32-bit address width when this property is missing.
>
> Signed-off-by: Suraj Gupta <suraj.gupta2@....com>
> Fixes: b72db4005fe4 ("dmaengine: vdma: Add 64 bit addressing support to the driver")

Reviewed-by: Folker Schwesinger <dev@...ker-schwesinger.de>

> ---
>  drivers/dma/xilinx/xilinx_dma.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
> index fabff602065f..89a8254d9cdc 100644
> --- a/drivers/dma/xilinx/xilinx_dma.c
> +++ b/drivers/dma/xilinx/xilinx_dma.c
> @@ -131,6 +131,7 @@
>  #define XILINX_MCDMA_MAX_CHANS_PER_DEVICE	0x20
>  #define XILINX_DMA_MAX_CHANS_PER_DEVICE		0x2
>  #define XILINX_CDMA_MAX_CHANS_PER_DEVICE	0x1
> +#define XILINX_DMA_DFAULT_ADDRWIDTH		0x20
>  
>  #define XILINX_DMA_DMAXR_ALL_IRQ_MASK	\
>  		(XILINX_DMA_DMASR_FRM_CNT_IRQ | \
> @@ -3159,7 +3160,7 @@ static int xilinx_dma_probe(struct platform_device *pdev)
>  	struct device_node *node = pdev->dev.of_node;
>  	struct xilinx_dma_device *xdev;
>  	struct device_node *child, *np = pdev->dev.of_node;
> -	u32 num_frames, addr_width, len_width;
> +	u32 num_frames, addr_width = XILINX_DMA_DFAULT_ADDRWIDTH, len_width;
>  	int i, err;
>  
>  	/* Allocate and initialize the DMA engine structure */
> @@ -3235,7 +3236,9 @@ static int xilinx_dma_probe(struct platform_device *pdev)
>  
>  	err = of_property_read_u32(node, "xlnx,addrwidth", &addr_width);
>  	if (err < 0)
> -		dev_warn(xdev->dev, "missing xlnx,addrwidth property\n");
> +		dev_warn(xdev->dev,
> +			 "missing xlnx,addrwidth property, using default value %d\n",
> +			 XILINX_DMA_DFAULT_ADDRWIDTH);
>  
>  	if (addr_width > 32)
>  		xdev->ext_addr = true;