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

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Message-ID: <7bea4592-01d6-4e19-90e4-e645dfe9631e@ti.com>
Date: Mon, 27 Jan 2025 16:27:57 +0530
From: "Kumar, Udit" <u-kumar1@...com>
To: Yemike Abhilash Chandra <y-abhilashchandra@...com>,
        <peter.ujfalusi@...il.com>, <vkoul@...nel.org>
CC: <vaishnav.a@...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

Hi Abhilash,

On 1/17/2025 5:47 PM, 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

This should carry fixes tag


> variable and directly using the one from the dma_device structure.
>
> 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);

With addition of fixes tag in subject,

Reviewed-by: Udit Kumar <u-kumar1@...com>


>   	if (!chan) {
>   		dev_err(ud->dev, "get channel fail in %s.\n", __func__);