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

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Message-ID: <20251216052156.GB6413@hailin-HP-Pavilion-Laptop-14-dv0xxx>
Date: Tue, 16 Dec 2025 13:21:56 +0800
From: Encrow Thorne <jyc0019@...il.com>
To: Guodong Xu <guodong@...cstar.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 Thu, Dec 11, 2025 at 03:35:26PM +0800, Guodong Xu wrote:
> 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?
> 
 Good point.
 
 Thank you for your suggestions, I will fix them in v2.

 				- Encrow
> Best regards,
> Guodong
> 
> >  	spacemit_i2c_reset(i2c);
> >
> >  	i2c_set_adapdata(&i2c->adapt, i2c);
> >