Re: [PATCH 13/17] i3c: renesas: Update HW registers after SW computations are done

On Fri, May 22, 2026 at 01:18:11PM +0300, Claudiu Beznea wrote:
> From: Claudiu Beznea <[email protected]>
>
> renesas_i3c_bus_init() performs a number of computations and software
> cache updates, interleaving them with hardware register writes. While
> this works today, it makes it harder to minimize the time the controller
> must remain powered when runtime PM is introduced.
>
> Perform all software computations and cache updates first, then update
> the hardware registers. This prepares for future runtime PM support.
>
> Signed-off-by: Claudiu Beznea <[email protected]>
> ---

Reviewed-by: Frank Li <[email protected]>

>  drivers/i3c/master/renesas-i3c.c | 28 ++++++++++++++--------------
>  1 file changed, 14 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/i3c/master/renesas-i3c.c b/drivers/i3c/master/renesas-i3c.c
> index 865e67ac0fd2..631c9c5d8038 100644
> --- a/drivers/i3c/master/renesas-i3c.c
> +++ b/drivers/i3c/master/renesas-i3c.c
> @@ -550,10 +550,6 @@ static int renesas_i3c_bus_init(struct i3c_master_controller *m)
>  	if (!i3c->rate)
>  		return -EINVAL;
>
> -	ret = renesas_i3c_reset(i3c);
> -	if (ret)
> -		return ret;
> -
>  	i2c_total_ticks = DIV_ROUND_UP(i3c->rate, bus->scl_rate.i2c);
>  	i3c_total_ticks = DIV_ROUND_UP(i3c->rate, bus->scl_rate.i3c);
>
> @@ -604,27 +600,31 @@ static int renesas_i3c_bus_init(struct i3c_master_controller *m)
>  			STDBR_SBRHO(double_SBR, od_high_ticks) |
>  			STDBR_SBRLP(pp_low_ticks) |
>  			STDBR_SBRHP(pp_high_ticks);
> -	renesas_writel(i3c->regs, STDBR, i3c->i3c_STDBR);
>
>  	/* Extended Bit Rate setting */
>  	i3c->extbr = EXTBR_EBRLO(od_low_ticks) | EXTBR_EBRHO(od_high_ticks) |
>  		     EXTBR_EBRLP(pp_low_ticks) | EXTBR_EBRHP(pp_high_ticks);
> -	renesas_writel(i3c->regs, EXTBR, i3c->extbr);
> -
> -	renesas_writel(i3c->regs, REFCKCTL, REFCKCTL_IREFCKS(cks));
> -	i3c->refclk_div = cks;
> -
> -	/* I3C hw init*/
> -	renesas_i3c_hw_init(i3c);
>
>  	ret = i3c_master_get_free_addr(m, 0);
>  	if (ret < 0)
>  		return ret;
>
> +	info.dyn_addr = ret;
>  	i3c->dyn_addr = ret;
> -	renesas_writel(i3c->regs, MSDVAD, MSDVAD_MDYAD(ret) | MSDVAD_MDYADV);
> +	i3c->refclk_div = cks;
> +
> +	ret = renesas_i3c_reset(i3c);
> +	if (ret)
> +		return ret;
> +
> +	renesas_writel(i3c->regs, STDBR, i3c->i3c_STDBR);
> +	renesas_writel(i3c->regs, EXTBR, i3c->extbr);
> +	renesas_writel(i3c->regs, REFCKCTL, REFCKCTL_IREFCKS(cks));
> +	renesas_writel(i3c->regs, MSDVAD, MSDVAD_MDYAD(i3c->dyn_addr) | MSDVAD_MDYADV);
> +
> +	/* I3C hw init*/
> +	renesas_i3c_hw_init(i3c);
>
> -	info.dyn_addr = ret;
>  	return i3c_master_set_info(&i3c->base, &info);
>  }
>
> --
> 2.43.0
>

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