linux-kernel - Re: [PATCH v3 3/3] i3c: dw: Preserve DAT entry bits when restoring addresses

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Message-ID: <aSSeu6HFXLIcVjZz@lizhi-Precision-Tower-5810>
Date: Mon, 24 Nov 2025 13:06:51 -0500
From: Frank Li <Frank.li@....com>
To: adrianhoyin.ng@...era.com
Cc: alexandre.belloni@...tlin.com, linux-i3c@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/3] i3c: dw: Preserve DAT entry bits when restoring
 addresses

On Sat, Nov 22, 2025 at 02:00:41AM +0800, adrianhoyin.ng@...era.com wrote:
> From: Adrian Ng Ho Yin <adrianhoyin.ng@...era.com>
>
> Update dw_i3c_master_restore_addrs() to preserve existing bits in each
> Device Address Table (DAT) entry when restoring addresses. This prevents
> overwriting configuration bits during PM runtime resumes.
>
> Signed-off-by: Adrian Ng Ho Yin <adrianhoyin.ng@...era.com>
> ---
>  drivers/i3c/master/dw-i3c-master.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c
> index e228c60840af..37275f7b6c61 100644
> --- a/drivers/i3c/master/dw-i3c-master.c
> +++ b/drivers/i3c/master/dw-i3c-master.c
> @@ -1723,11 +1723,16 @@ static void dw_i3c_master_restore_addrs(struct dw_i3c_master *master)
>  		if (master->free_pos & BIT(pos))
>  			continue;
>
> -		if (master->devs[pos].is_i2c_addr)
> -			reg_val = DEV_ADDR_TABLE_LEGACY_I2C_DEV |
> +		reg_val = readl(master->regs + DEV_ADDR_TABLE_LOC(master->datstartaddr, pos));
> +
> +		if (master->devs[pos].is_i2c_addr) {
> +			reg_val &= ~(GENMASK(6, 0));

#define at MASK for it

#define DEV_ADDR_TABLE_DYNAMIC_MASK	GENMASK(23, 16);
#define DEV_ADDR_TABLE_DYNAMIC_ADDR(x)  FIELD_PREP(DEV_ADDR_TABLE_DYNAMIC_MASK, x) //(((x) << 16) & GENMASK(23, 16))

Create a patch to just change it. And use DEV_ADDR_TABLE_DYNAMIC_MASK at
this patch.

Frank

> +			reg_val |= DEV_ADDR_TABLE_LEGACY_I2C_DEV |
>  			       DEV_ADDR_TABLE_STATIC_ADDR(master->devs[pos].addr);
> -		else
> -			reg_val = DEV_ADDR_TABLE_DYNAMIC_ADDR(master->devs[pos].addr);
> +		} else {
> +			reg_val &= ~(GENMASK(23, 16));
> +			reg_val |= DEV_ADDR_TABLE_DYNAMIC_ADDR(master->devs[pos].addr);
> +		}
>
>  		writel(reg_val, master->regs + DEV_ADDR_TABLE_LOC(master->datstartaddr, pos));
>  	}
> --
> 2.49.GIT
>