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

[Frank Li]

On Thu, Aug 13, 2026 at 12:56:09PM +0800, Jisheng Zhang wrote:
> 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@xxxxxxxxxx>
> > > ---
> > >  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


https://lore.kernel.org/linux-i3c/20260731070150.2519825-1-tommaso.merciai.xr@xxxxxxxxxxxxxx/

Need fix newdevs, it should be 0, not 0xf.

Frank

>
> >
> > 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
> > >