linux-kernel - Re: [PATCH RFC] dmaengine: ti: k3-udma: Use cap_mask directly from dma

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Message-ID: <0fca4108-a24c-4259-af88-82114ce3c1d3@gmail.com>
Date: Wed, 22 Jan 2025 17:24:22 +0200
From: Péter Ujfalusi <peter.ujfalusi@...il.com>
To: Yemike Abhilash Chandra <y-abhilashchandra@...com>, vkoul@...nel.org
Cc: vaishnav.a@...com, u-kumar1@...com, dmaengine@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] dmaengine: ti: k3-udma: Use cap_mask directly from
 dma_device structure instead of a local copy



On 17/01/2025 14:17, Yemike Abhilash Chandra wrote:
> Currently, a local dma_cap_mask_t variable is used to store device
> cap_mask within udma_of_xlate(). However, the DMA_PRIVATE flag in
> the device cap_mask can get cleared when the last channel is released.
> This can happen right after storing the cap_mask locally in
> udma_of_xlate() and subsequent dma_request_channel() can fail due to
> mismatch in the cap_mask. Fix this by removing the local dma_cap_mask_t
> variable and directly using the one from the dma_device structure.

Acked-by: Peter Ujfalusi <peter.ujfalusi@...il.com>

> 
> Signed-off-by: Vaishnav Achath <vaishnav.a@...com>
> Signed-off-by: Yemike Abhilash Chandra <y-abhilashchandra@...com>
> ---
>  drivers/dma/ti/k3-udma.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/dma/ti/k3-udma.c b/drivers/dma/ti/k3-udma.c
> index 7ed1956b4642..c775a2284e86 100644
> --- a/drivers/dma/ti/k3-udma.c
> +++ b/drivers/dma/ti/k3-udma.c
> @@ -4246,7 +4246,6 @@ static struct dma_chan *udma_of_xlate(struct of_phandle_args *dma_spec,
>  				      struct of_dma *ofdma)
>  {
>  	struct udma_dev *ud = ofdma->of_dma_data;
> -	dma_cap_mask_t mask = ud->ddev.cap_mask;
>  	struct udma_filter_param filter_param;
>  	struct dma_chan *chan;
>  
> @@ -4278,7 +4277,7 @@ static struct dma_chan *udma_of_xlate(struct of_phandle_args *dma_spec,
>  		}
>  	}
>  
> -	chan = __dma_request_channel(&mask, udma_dma_filter_fn, &filter_param,
> +	chan = __dma_request_channel(&ud->ddev.cap_mask, udma_dma_filter_fn, &filter_param,
>  				     ofdma->of_node);
>  	if (!chan) {
>  		dev_err(ud->dev, "get channel fail in %s.\n", __func__);

-- 
Péter