Re: [PATCH] i3c: dw: reduce do_daa time if there's no client

[Jisheng Zhang <jszhang@kernel.org>]

On Wed, Aug 05, 2026 at 04:05:35PM -0400, Frank Li wrote:
> On Mon, Aug 03, 2026 at 10:03:07PM +0800, Jisheng Zhang wrote:
> > If there's no client, wait for completion will timeout, then there's no
> > need to add i3c dev at all. This can save boot time by ~6s if there's
> > no client connected to the i3c interface.
> >
> > Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> > ---
> >  drivers/i3c/master/dw-i3c-master.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c
> > index 0625587f1527..18ebf304029a 100644
> > --- a/drivers/i3c/master/dw-i3c-master.c
> > +++ b/drivers/i3c/master/dw-i3c-master.c
> > @@ -885,8 +885,10 @@ static int dw_i3c_master_daa(struct i3c_master_controller *m)
> >  		      COMMAND_PORT_ROC;
> >
> >  	dw_i3c_master_enqueue_xfer(master, xfer);
> > -	if (!wait_for_completion_timeout(&xfer->comp, XFER_TIMEOUT))
> > +	if (!wait_for_completion_timeout(&xfer->comp, XFER_TIMEOUT)) {
> >  		dw_i3c_master_dequeue_xfer(master, xfer);
> > +		goto rpm_out;
> 
> not sure why save 6s. timeout already happen, does register i3c device
> takes 6s?

sorry, typo, s/6/4
For example if the maxdev == 4, when there's no i3c device connected, the
max cmd->rx_len = 0 after timeout, then newdevs = 0xf, then go through
the i3c_master_add_i3c_dev_locked(), each take ~1s, so adds up to 4s

> 
> And if do_daa find 3 devices, then timeout, you skip register found 3
> devices.

It's the addr assign cmd timeout, so if 3 devices respond, the addr
assign cmd won't timeout.

> 
> Frank
> 
> > +	}
> >
> >  	newdevs = GENMASK(master->maxdevs - cmd->rx_len - 1, 0);
> >  	newdevs &= ~olddevs;
> > --
> > 2.53.0
> >