linux-kernel - Re: [PATCH 2/3] i2c: k1: add reset support

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Message-ID: <20251211073526.3164875-1-guodong@riscstar.com>
Date: Thu, 11 Dec 2025 15:35:26 +0800
From: Guodong Xu <guodong@...cstar.com>
To: jyc0019@...il.com
Cc: alex@...ti.fr,
	andi.shyti@...nel.org,
	aou@...s.berkeley.edu,
	conor+dt@...nel.org,
	devicetree@...r.kernel.org,
	dlan@...too.org,
	krzk+dt@...nel.org,
	linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	p.zabel@...gutronix.de,
	palmer@...belt.com,
	pjw@...nel.org,
	robh@...nel.org,
	spacemit@...ts.linux.dev,
	troy.mitchell@...ux.spacemit.com,
	troymitchell988@...il.com
Subject: Re: [PATCH 2/3] i2c: k1: add reset support

On Wed, Nov 19, 2025 at 07:46:44PM +0800, Encrow Thorne wrote:
> Add reset control handling to the K1 I2C driver.
>
> Signed-off-by: Encrow Thorne <jyc0019@...il.com>
> ---
>  drivers/i2c/busses/i2c-k1.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-k1.c b/drivers/i2c/busses/i2c-k1.c
> index 6b918770e612..64d817d8315d 100644
> --- a/drivers/i2c/busses/i2c-k1.c
> +++ b/drivers/i2c/busses/i2c-k1.c
> @@ -10,6 +10,7 @@
>   #include <linux/module.h>
>   #include <linux/of_address.h>
>   #include <linux/platform_device.h>
> + #include <linux/reset.h>
>
>  /* spacemit i2c registers */
>  #define SPACEMIT_ICR		 0x0		/* Control register */
> @@ -113,6 +114,7 @@ struct spacemit_i2c_dev {
>  	void __iomem *base;
>  	int irq;
>  	u32 clock_freq;
> +	struct reset_control *resets;

Thanks for the patch! A few suggestions to simplify this:

The reset_control structure doesn't need to be stored in the device
struct since the devm API automatically manages the resource lifecycle.

>
>  	struct i2c_msg *msgs;
>  	u32 msg_num;
> @@ -571,6 +573,15 @@ static int spacemit_i2c_probe(struct platform_device *pdev)

Please use a local variable in the probe function instead:

       struct reset_control *rst;

>  	if (IS_ERR(clk))
>  		return dev_err_probe(dev, PTR_ERR(clk), "failed to enable bus clock");
>
> +	i2c->resets = devm_reset_control_get_optional(dev, NULL);

There is a new API, I would suggest this:
       rst = devm_reset_control_get_optional_exclusive_deasserted(dev, NULL);


> +	if (IS_ERR(i2c->resets))
> +		return dev_err_probe(dev, PTR_ERR(i2c->resets),
> +				    "failed to get reset\n");
> +
> +	reset_control_assert(i2c->resets);
> +	udelay(2);
> +	reset_control_deassert(i2c->resets);
> +

Why you need to call assert() then deassert()?
Wouldn't the single API fit?

Best regards,
Guodong

>  	spacemit_i2c_reset(i2c);
>
>  	i2c_set_adapdata(&i2c->adapt, i2c);
>