Re: [PATCH 02/10] dma-engine: sun4i: Add has_reset option to quirk

[Philipp Zabel <p.zabel@pengutronix.de>]

On Do, 2024-10-24 at 08:49 +0200, Csókás, Bence wrote:
> From: Mesih Kilinc <mesihkilinc@gmail.com>
> 
> Allwinner suniv F1C100s has a reset bit for DMA in CCU. Sun4i do not
> has this bit but in order to support suniv we need to add it. So add
> support for reset bit.
> 
> Signed-off-by: Mesih Kilinc <mesihkilinc@gmail.com>
> ---
>  drivers/dma/sun4i-dma.c | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/drivers/dma/sun4i-dma.c b/drivers/dma/sun4i-dma.c
> index 5efbed7c546f..0b99b3884971 100644
> --- a/drivers/dma/sun4i-dma.c
> +++ b/drivers/dma/sun4i-dma.c
> @@ -15,6 +15,7 @@
>  #include <linux/of_dma.h>
>  #include <linux/of_device.h>
>  #include <linux/platform_device.h>
> +#include <linux/reset.h>
>  #include <linux/slab.h>
>  #include <linux/spinlock.h>
>  
> @@ -159,6 +160,7 @@ struct sun4i_dma_config {
>  	u8 ddma_drq_sdram;
>  
>  	u8 max_burst;
> +	bool has_reset;
>  };
>  
>  struct sun4i_dma_pchan {
> @@ -208,6 +210,7 @@ struct sun4i_dma_dev {
>  	int				irq;
>  	spinlock_t			lock;
>  	const struct sun4i_dma_config *cfg;
> +	struct reset_control *rst;
>  };
>  
>  static struct sun4i_dma_dev *to_sun4i_dma_dev(struct dma_device *dev)
> @@ -1215,6 +1218,15 @@ static int sun4i_dma_probe(struct platform_device *pdev)
>  		return PTR_ERR(priv->clk);
>  	}
>  
> +	if (priv->cfg->has_reset) {
> +		priv->rst = devm_reset_control_get_exclusive(&pdev->dev,
> +							       NULL);

Aligning to open parenthesis will make checkpatch --strict happy.

> +		if (IS_ERR(priv->rst)) {
> +			dev_err(&pdev->dev, "Failed to get reset control\n");

Consider using dev_err_probe() here.

> +			return PTR_ERR(priv->rst);
> +		}
> +	}
> +
>  	platform_set_drvdata(pdev, priv);
>  	spin_lock_init(&priv->lock);
>  
> @@ -1287,6 +1299,16 @@ static int sun4i_dma_probe(struct platform_device *pdev)
>  		return ret;
>  	}
>  
> +	/* Deassert the reset control */
> +	if (priv->rst) {
> +		ret = reset_control_deassert(priv->rst);
> +		if (ret) {
> +			dev_err(&pdev->dev,
> +				"Failed to deassert the reset control\n");
> +			goto err_clk_disable;
> +		}
> +	}

You can just call reset_control_deassert() unconditionally, it accepts
a NULL parameter:

  https://docs.kernel.org/driver-api/reset.html#c.reset_control_deassert


regards
Philipp