linux-kernel - Re: [PATCH v3 2/8] dmaengine: mmp_pdma: Add optional clock support

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Message-ID: <20250724123128-GYB748228@gentoo>
Date: Thu, 24 Jul 2025 20:31:28 +0800
From: Yixun Lan <dlan@...too.org>
To: Guodong Xu <guodong@...cstar.com>
Cc: Vinod Koul <vkoul@...nel.org>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Duje Mihanović <duje.mihanovic@...le.hr>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>, Alexandre Ghiti <alex@...ti.fr>,
	Alex Elder <elder@...cstar.com>,
	Vivian Wang <wangruikang@...as.ac.cn>, dmaengine@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-riscv@...ts.infradead.org, spacemit@...ts.linux.dev
Subject: Re: [PATCH v3 2/8] dmaengine: mmp_pdma: Add optional clock support

Hi Guodong,

I personally find the word 'optional' introducing some confusions..
I can understand from driver perspective, it's kind of optional,
but from SpacemiT K1 perspective, it's mandatory for this driver
(the 'clocks' property of DT is in 'required' section)

feel free to improve the commit message, maybe add some motivation
hehind this

On 17:39 Mon 14 Jul     , Guodong Xu wrote:
> Add support for retrieving and enabling an optional clock during
> mmp_pdma_probe().
> 
> Signed-off-by: Guodong Xu <guodong@...cstar.com>
> ---
> v3: No change.
> v2: No change.
> ---
>  drivers/dma/mmp_pdma.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/dma/mmp_pdma.c b/drivers/dma/mmp_pdma.c
> index a95d31103d3063a1d11177a1a37b89ac2fd213e9..4a6dbf55823722d26cc69379d22aaa88fbe19313 100644
> --- a/drivers/dma/mmp_pdma.c
> +++ b/drivers/dma/mmp_pdma.c
> @@ -15,6 +15,7 @@
>  #include <linux/device.h>
>  #include <linux/platform_data/mmp_dma.h>
>  #include <linux/dmapool.h>
> +#include <linux/clk.h>
>  #include <linux/of_dma.h>
>  #include <linux/of.h>
>  
> @@ -1019,6 +1020,7 @@ static int mmp_pdma_probe(struct platform_device *op)
>  {
>  	struct mmp_pdma_device *pdev;
>  	struct mmp_dma_platdata *pdata = dev_get_platdata(&op->dev);
> +	struct clk *clk;
>  	int i, ret, irq = 0;
>  	int dma_channels = 0, irq_num = 0;
>  	const enum dma_slave_buswidth widths =
> @@ -1037,6 +1039,10 @@ static int mmp_pdma_probe(struct platform_device *op)
>  	if (IS_ERR(pdev->base))
>  		return PTR_ERR(pdev->base);
>  
> +	clk = devm_clk_get_optional_enabled(pdev->dev, NULL);
> +	if (IS_ERR(clk))
> +		return PTR_ERR(clk);
> +
>  	if (pdev->dev->of_node) {
>  		/* Parse new and deprecated dma-channels properties */
>  		if (of_property_read_u32(pdev->dev->of_node, "dma-channels",
> 
> -- 
> 2.43.0
> 

-- 
Yixun Lan (dlan)