linux-kernel - Re: [PATCH 1/6] dma:at_hdmac:Use devm_clk_get

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Message-ID: <20240823125821.000032c2@Huawei.com>
Date: Fri, 23 Aug 2024 12:58:21 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Liao Yuanhong <liaoyuanhong@...o.com>
CC: <vkoul@...nel.org>, <linux-arm-kernel@...ts.infradead.org>,
	<dmaengine@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/6] dma:at_hdmac:Use devm_clk_get_enabled() helpers

On Fri, 23 Aug 2024 18:19:28 +0800
Liao Yuanhong <liaoyuanhong@...o.com> wrote:

> Use devm_clk_get_enabled() instead of clk functions in at_hdmac.

Doesn't this stop the clock being turned of in suspend?

Or is there some magic handling that which I'm not aware of?


> 
> Signed-off-by: Liao Yuanhong <liaoyuanhong@...o.com>
> ---
>  drivers/dma/at_hdmac.c | 22 +++++-----------------
>  1 file changed, 5 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
> index 40052d1bd0b5..b1e10541cb12 100644
> --- a/drivers/dma/at_hdmac.c
> +++ b/drivers/dma/at_hdmac.c
> @@ -337,7 +337,6 @@ static inline u8 convert_buswidth(enum dma_slave_buswidth addr_width)
>   * struct at_dma - internal representation of an Atmel HDMA Controller
>   * @dma_device: dmaengine dma_device object members
>   * @regs: memory mapped register base
> - * @clk: dma controller clock
>   * @save_imr: interrupt mask register that is saved on suspend/resume cycle
>   * @all_chan_mask: all channels availlable in a mask
>   * @lli_pool: hw lli table
> @@ -347,7 +346,6 @@ static inline u8 convert_buswidth(enum dma_slave_buswidth addr_width)
>  struct at_dma {
>  	struct dma_device	dma_device;
>  	void __iomem		*regs;
> -	struct clk		*clk;
>  	u32			save_imr;
>  
>  	u8			all_chan_mask;
> @@ -1942,6 +1940,7 @@ static int __init at_dma_probe(struct platform_device *pdev)
>  	int			err;
>  	int			i;
>  	const struct at_dma_platform_data *plat_dat;
> +	struct clk	*clk;
>  
>  	/* setup platform data for each SoC */
>  	dma_cap_set(DMA_MEMCPY, at91sam9rl_config.cap_mask);
> @@ -1975,20 +1974,16 @@ static int __init at_dma_probe(struct platform_device *pdev)
>  	atdma->dma_device.cap_mask = plat_dat->cap_mask;
>  	atdma->all_chan_mask = (1 << plat_dat->nr_channels) - 1;
>  
> -	atdma->clk = devm_clk_get(&pdev->dev, "dma_clk");
> -	if (IS_ERR(atdma->clk))
> -		return PTR_ERR(atdma->clk);
> -
> -	err = clk_prepare_enable(atdma->clk);
> -	if (err)
> -		return err;
> +	clk = devm_clk_get_enabled(&pdev->dev, "dma_clk");
> +	if (IS_ERR(clk))
> +		return PTR_ERR(clk);
>  
>  	/* force dma off, just in case */
>  	at_dma_off(atdma);
>  
>  	err = request_irq(irq, at_dma_interrupt, 0, "at_hdmac", atdma);
>  	if (err)
> -		goto err_irq;
> +		return err;
>  
>  	platform_set_drvdata(pdev, atdma);
>  
> @@ -2105,8 +2100,6 @@ static int __init at_dma_probe(struct platform_device *pdev)
>  	dma_pool_destroy(atdma->lli_pool);
>  err_desc_pool_create:
>  	free_irq(platform_get_irq(pdev, 0), atdma);
> -err_irq:
> -	clk_disable_unprepare(atdma->clk);
>  	return err;
>  }
>  
> @@ -2130,8 +2123,6 @@ static void at_dma_remove(struct platform_device *pdev)
>  		atc_disable_chan_irq(atdma, chan->chan_id);
>  		list_del(&chan->device_node);
>  	}
> -
> -	clk_disable_unprepare(atdma->clk);
>  }
>  
>  static void at_dma_shutdown(struct platform_device *pdev)
> @@ -2139,7 +2130,6 @@ static void at_dma_shutdown(struct platform_device *pdev)
>  	struct at_dma	*atdma = platform_get_drvdata(pdev);
>  
>  	at_dma_off(platform_get_drvdata(pdev));
> -	clk_disable_unprepare(atdma->clk);
>  }
>  
>  static int at_dma_prepare(struct device *dev)
> @@ -2194,7 +2184,6 @@ static int at_dma_suspend_noirq(struct device *dev)
>  
>  	/* disable DMA controller */
>  	at_dma_off(atdma);
> -	clk_disable_unprepare(atdma->clk);
>  	return 0;
>  }
>  
> @@ -2223,7 +2212,6 @@ static int at_dma_resume_noirq(struct device *dev)
>  	struct dma_chan *chan, *_chan;
>  
>  	/* bring back DMA controller */
> -	clk_prepare_enable(atdma->clk);
>  	dma_writel(atdma, EN, AT_DMA_ENABLE);
>  
>  	/* clear any pending interrupt */