linux-kernel - Re: [PATCH v5 2/5] dma-engine: sun4i: Add has

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Message-ID: <20241102174516.02d124d6@minigeek.lan>
Date: Sat, 2 Nov 2024 17:45:16 +0000
From: Andre Przywara <andre.przywara@....com>
To: "Csókás, Bence" <csokas.bence@...lan.hu>
Cc: <dmaengine@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
 <linux-sunxi@...ts.linux.dev>, <linux-kernel@...r.kernel.org>, Mesih Kilinc
 <mesihkilinc@...il.com>, Krzysztof Kozlowski <krzk@...nel.org>, Vinod Koul
 <vkoul@...nel.org>, Chen-Yu Tsai <wens@...e.org>, Jernej Skrabec
 <jernej.skrabec@...il.com>, Samuel Holland <samuel@...lland.org>, Philipp
 Zabel <p.zabel@...gutronix.de>
Subject: Re: [PATCH v5 2/5] dma-engine: sun4i: Add has_reset option to quirk

On Sat, 2 Nov 2024 10:31:41 +0100
"Csókás, Bence" <csokas.bence@...lan.hu> wrote:

Hi,

> From: Mesih Kilinc <mesihkilinc@...il.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@...il.com>
> [ csokas.bence: Rebased and addressed comments ]
> Signed-off-by: Csókás, Bence <csokas.bence@...lan.hu>
> ---
> 
> Notes:
>     Changes in v2:
>     * Call reset_control_deassert() unconditionally, as it supports optional resets
>     * Use dev_err_probe()
>     * Whitespace
>     Changes in v3:
>     * More dev_err_probe() fixes
>     Changes in v4:
>     * Use return value of dev_err_probe()
>     Changes in v5:
>     * More whitespace
> 
>  drivers/dma/sun4i-dma.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/dma/sun4i-dma.c b/drivers/dma/sun4i-dma.c
> index b2c1e4b9f696..9d1e3c51342d 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 +1218,13 @@ 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);

Can't we use devm_reset_control_get_optional_exclusive(), and then save
this whole has_reset bit?

> +		if (IS_ERR(priv->rst))
> +			return dev_err_probe(&pdev->dev, PTR_ERR(priv->rst),
> +					     "Failed to get reset control\n");
> +	}
> +
>  	platform_set_drvdata(pdev, priv);
>  	spin_lock_init(&priv->lock);
>  
> @@ -1287,6 +1297,14 @@ static int sun4i_dma_probe(struct platform_device *pdev)
>  		return ret;
>  	}
>  
> +	/* Deassert the reset control */
> +	ret = reset_control_deassert(priv->rst);
> +	if (ret) {
> +		dev_err_probe(&pdev->dev, ret,
> +			      "Failed to deassert the reset control\n");
> +		goto err_clk_disable;
> +	}
> +
>  	/*
>  	 * Make sure the IRQs are all disabled and accounted for. The bootloader
>  	 * likes to leave these dirty
> @@ -1355,6 +1373,7 @@ static struct sun4i_dma_config sun4i_a10_dma_cfg = {
>  	.ddma_drq_sdram		= SUN4I_DDMA_DRQ_TYPE_SDRAM,
>  
>  	.max_burst		= SUN4I_MAX_BURST,
> +	.has_reset		= false,
>  };
>  
>  static const struct of_device_id sun4i_dma_match[] = {