linux-kernel - Re: [PATCH 2/3] dma: amlogic: Add general DMA driver for SoCs

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Message-ID: <176db27e-a689-4de1-898b-527420bf68dc@kernel.org>
Date: Tue, 16 Dec 2025 09:46:45 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: xianwei.zhao@...ogic.com, Vinod Koul <vkoul@...nel.org>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Kees Cook <kees@...nel.org>,
 "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc: linux-amlogic@...ts.infradead.org, dmaengine@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-hardening@...r.kernel.org
Subject: Re: [PATCH 2/3] dma: amlogic: Add general DMA driver for SoCs

On 16/12/2025 09:03, Xianwei Zhao via B4 Relay wrote:
> From: Xianwei Zhao <xianwei.zhao@...ogic.com>
> 
> Amlogic SoCs include a general-purpose DMA controller that can be used
> by multiple peripherals, such as I2C PIO and I3C. Each peripheral group
> is associated with a dedicated DMA channel in hardware.
> 
> Signed-off-by: Xianwei Zhao <xianwei.zhao@...ogic.com>
> ---
>  drivers/dma/Kconfig       |   8 +
>  drivers/dma/Makefile      |   1 +
>  drivers/dma/amlogic-dma.c | 567 ++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 576 insertions(+)
> 
> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> index 8bb0a119ecd4..fc7f70e22c22 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -85,6 +85,14 @@ config AMCC_PPC440SPE_ADMA
>  	help
>  	  Enable support for the AMCC PPC440SPe RAID engines.
>  
> +config AMLOGIC_DMA
> +	tristate "Amlogic genneral DMA support"
> +	depends on ARCH_MESON

Missing compile test.

> +	select DMA_ENGINE
> +	select REGMAP_MMIO
> +	help
> +	  Enable support for the Amlogic general DMA engines.
> +

> +
> +	ret = of_dma_controller_register(np, aml_of_dma_xlate, aml_dma);
> +	if (ret)
> +		return ret;
> +
> +	regmap_write(aml_dma->regmap, RCH_INT_MASK, 0xffffffff);
> +	regmap_write(aml_dma->regmap, WCH_INT_MASK, 0xffffffff);
> +
> +	ret = devm_request_irq(&pdev->dev, aml_dma->irq, aml_dma_interrupt_handler,
> +			       IRQF_SHARED, dev_name(&pdev->dev), aml_dma);
> +	if (ret)
> +		return ret;
> +
> +	dev_info(aml_dma->dma_device.dev, "initialized\n");

Useless message, drop. This does not look like useful printk message.
Drivers should be silent on success:
https://elixir.bootlin.com/linux/v6.15-rc7/source/Documentation/process/coding-style.rst#L913
https://elixir.bootlin.com/linux/v6.15-rc7/source/Documentation/process/debugging/driver_development_debugging_guide.rst#L79

> +
> +	return 0;
> +}
> +
> +static const struct of_device_id aml_dma_ids[] = {
> +	{ .compatible = "amlogic,general-dma", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, aml_dma_ids);
> +
> +static struct platform_driver aml_dma_driver = {
> +	.probe = aml_dma_probe,
> +	.driver		= {
> +		.name	= "aml-dma",
> +		.of_match_table = aml_dma_ids,
> +	},
> +};
> +
> +module_platform_driver(aml_dma_driver);
> +
> +MODULE_DESCRIPTION("GENERAL DMA driver for Amlogic");
> +MODULE_AUTHOR("Xianwei Zhao <xianwei.zhao@...ogic.com>");
> +MODULE_ALIAS("platform:aml-dma");
> +MODULE_LICENSE("GPL");
> 

Best regards,
Krzysztof