linux-kernel - Re: [PATCH v8 1/4] i2c: tegra: Do not configure DMA if not supported

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <d336ce08-4e35-4c14-9f5d-e777f7d91cc3@nvidia.com>
Date: Wed, 17 Sep 2025 15:08:03 +0100
From: Jon Hunter <jonathanh@...dia.com>
To: Kartik Rajput <kkartik@...dia.com>, akhilrajeev@...dia.com,
 andi.shyti@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
 conor+dt@...nel.org, thierry.reding@...il.com, ldewangan@...dia.com,
 digetx@...il.com, linux-i2c@...r.kernel.org, devicetree@...r.kernel.org,
 linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 1/4] i2c: tegra: Do not configure DMA if not supported


On 17/09/2025 09:56, Kartik Rajput wrote:
> On Tegra264, not all I2C controllers have the necessary interface to
> GPC DMA, this causes failures when function tegra_i2c_init_dma()
> is called.
> 
> Ensure that "dmas" device-tree property is present before initializing
> DMA in function tegra_i2c_init_dma().
> 
> Signed-off-by: Kartik Rajput <kkartik@...dia.com>
> ---
> v2 -> v4:
> 	* Add debug print if DMA is not supported by the I2C controller.
> v1 -> v2:
> 	* Update commit message to clarify that some I2C controllers may
> 	  not have the necessary interface to GPC DMA.
> ---
>   drivers/i2c/busses/i2c-tegra.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> index e533460bccc3..d908e5e3f0af 100644
> --- a/drivers/i2c/busses/i2c-tegra.c
> +++ b/drivers/i2c/busses/i2c-tegra.c
> @@ -446,6 +446,11 @@ static int tegra_i2c_init_dma(struct tegra_i2c_dev *i2c_dev)
>   	u32 *dma_buf;
>   	int err;
>   
> +	if (!of_property_present(i2c_dev->dev->of_node, "dmas")) {
> +		dev_dbg(i2c_dev->dev, "DMA not available, falling back to PIO\n");
> +		return 0;
> +	}
> +
>   	if (IS_VI(i2c_dev))
>   		return 0;
>   

No issue with this change, but we have a few checks for DMA support in 
this function and so it would be nice to have them altogether.

Jon

-- 
nvpublic