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* [PATCH v2] i3c: dw: reduce do_daa time if there's no client
@ 2026-08-14  4:20 Jisheng Zhang
  2026-08-14 16:38 ` Frank Li
  2026-08-18 21:18 ` Alexandre Belloni
  0 siblings, 2 replies; 3+ messages in thread
From: Jisheng Zhang @ 2026-08-14  4:20 UTC (permalink / raw)
  To: Alexandre Belloni, Frank Li; +Cc: linux-i3c, linux-kernel

dw_i3c_master_daa() derives the number of newly assigned dynamic
addresses from cmd->rx_len, the ISR sets it to the number of address
slots ENTDAA left unassigned. It starts out as zero, which already
means "every address was assigned", so a timed out transfer leaves
that value in place and it gets used as a result.

If there's no client connected, the addr assign cmd times out, then
the driver calls i3c_master_add_i3c_dev_locked() to add devices that
are not there, each costing about 1s, thus adds non necessary boot
time up to (maxdev * 1)s.

Start from maxdevs instead: no address is assigned before ENTDAA runs,
and make newdevs as 0 if the existing rx_len >= maxdevs.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---

since v1:
 - use another method to remove the non-necessary calling of
   i3c_master_add_i3c_dev_locked() if there's no client
 - update commit msg

 drivers/i3c/master/dw-i3c-master.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c
index 1053cfb05c05..883b542c7bfc 100644
--- a/drivers/i3c/master/dw-i3c-master.c
+++ b/drivers/i3c/master/dw-i3c-master.c
@@ -876,6 +876,7 @@ static int dw_i3c_master_daa(struct i3c_master_controller *m)
 		goto rpm_out;
 	}
 	cmd = &xfer->cmds[0];
+	cmd->rx_len = master->maxdevs;
 	cmd->cmd_hi = COMMAND_PORT_TRANSFER_ARG;
 	cmd->cmd_lo = COMMAND_PORT_DEV_COUNT(master->maxdevs - pos) |
 		      COMMAND_PORT_DEV_INDEX(pos) |
@@ -888,7 +889,10 @@ static int dw_i3c_master_daa(struct i3c_master_controller *m)
 	if (!wait_for_completion_timeout(&xfer->comp, XFER_TIMEOUT))
 		dw_i3c_master_dequeue_xfer(master, xfer);
 
-	newdevs = GENMASK(master->maxdevs - cmd->rx_len - 1, 0);
+	if (cmd->rx_len >= master->maxdevs)
+		newdevs = 0;
+	else
+		newdevs = GENMASK(master->maxdevs - cmd->rx_len - 1, 0);
 	newdevs &= ~olddevs;
 
 	for (pos = 0; pos < master->maxdevs; pos++) {
-- 
2.51.0


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^ permalink raw reply related	[flat|nested] 3+ messages in thread
* Re: [PATCH v2] i3c: dw: reduce do_daa time if there's no client
  2026-08-14  4:20 [PATCH v2] i3c: dw: reduce do_daa time if there's no client Jisheng Zhang
@ 2026-08-14 16:38 ` Frank Li
  2026-08-18 21:18 ` Alexandre Belloni
  1 sibling, 0 replies; 3+ messages in thread
From: Frank Li @ 2026-08-14 16:38 UTC (permalink / raw)
  To: Jisheng Zhang; +Cc: Alexandre Belloni, Frank Li, linux-i3c, linux-kernel

On Fri, Aug 14, 2026 at 12:20:15PM +0800, Jisheng Zhang wrote:
> dw_i3c_master_daa() derives the number of newly assigned dynamic
> addresses from cmd->rx_len, the ISR sets it to the number of address
> slots ENTDAA left unassigned. It starts out as zero, which already
> means "every address was assigned", so a timed out transfer leaves
> that value in place and it gets used as a result.
>
> If there's no client connected, the addr assign cmd times out, then
> the driver calls i3c_master_add_i3c_dev_locked() to add devices that
> are not there, each costing about 1s, thus adds non necessary boot
> time up to (maxdev * 1)s.
>
> Start from maxdevs instead: no address is assigned before ENTDAA runs,
> and make newdevs as 0 if the existing rx_len >= maxdevs.
>
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> ---

Reviewed-by: Frank Li <Frank.Li@nxp.com>

>
> since v1:
>  - use another method to remove the non-necessary calling of
>    i3c_master_add_i3c_dev_locked() if there's no client
>  - update commit msg
>
>  drivers/i3c/master/dw-i3c-master.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c
> index 1053cfb05c05..883b542c7bfc 100644
> --- a/drivers/i3c/master/dw-i3c-master.c
> +++ b/drivers/i3c/master/dw-i3c-master.c
> @@ -876,6 +876,7 @@ static int dw_i3c_master_daa(struct i3c_master_controller *m)
>  		goto rpm_out;
>  	}
>  	cmd = &xfer->cmds[0];
> +	cmd->rx_len = master->maxdevs;
>  	cmd->cmd_hi = COMMAND_PORT_TRANSFER_ARG;
>  	cmd->cmd_lo = COMMAND_PORT_DEV_COUNT(master->maxdevs - pos) |
>  		      COMMAND_PORT_DEV_INDEX(pos) |
> @@ -888,7 +889,10 @@ static int dw_i3c_master_daa(struct i3c_master_controller *m)
>  	if (!wait_for_completion_timeout(&xfer->comp, XFER_TIMEOUT))
>  		dw_i3c_master_dequeue_xfer(master, xfer);
>
> -	newdevs = GENMASK(master->maxdevs - cmd->rx_len - 1, 0);
> +	if (cmd->rx_len >= master->maxdevs)
> +		newdevs = 0;
> +	else
> +		newdevs = GENMASK(master->maxdevs - cmd->rx_len - 1, 0);
>  	newdevs &= ~olddevs;
>
>  	for (pos = 0; pos < master->maxdevs; pos++) {
> --
> 2.51.0
>

-- 
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^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: [PATCH v2] i3c: dw: reduce do_daa time if there's no client
  2026-08-14  4:20 [PATCH v2] i3c: dw: reduce do_daa time if there's no client Jisheng Zhang
  2026-08-14 16:38 ` Frank Li
@ 2026-08-18 21:18 ` Alexandre Belloni
  1 sibling, 0 replies; 3+ messages in thread
From: Alexandre Belloni @ 2026-08-18 21:18 UTC (permalink / raw)
  To: Jisheng Zhang; +Cc: Frank Li, linux-i3c, linux-kernel

Hi Jisheng,

On 14/08/2026 12:20:15+0800, Jisheng Zhang wrote:
> dw_i3c_master_daa() derives the number of newly assigned dynamic
> addresses from cmd->rx_len, the ISR sets it to the number of address
> slots ENTDAA left unassigned. It starts out as zero, which already
> means "every address was assigned", so a timed out transfer leaves
> that value in place and it gets used as a result.
> 
> If there's no client connected, the addr assign cmd times out, then
> the driver calls i3c_master_add_i3c_dev_locked() to add devices that
> are not there, each costing about 1s, thus adds non necessary boot
> time up to (maxdev * 1)s.
> 
> Start from maxdevs instead: no address is assigned before ENTDAA runs,
> and make newdevs as 0 if the existing rx_len >= maxdevs.
> 
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> ---
> 
> since v1:
>  - use another method to remove the non-necessary calling of
>    i3c_master_add_i3c_dev_locked() if there's no client
>  - update commit msg
> 
>  drivers/i3c/master/dw-i3c-master.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 

You'd have to rebase this one on i3c/next as it doesn't apply cleanly
anymore.

> diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c
> index 1053cfb05c05..883b542c7bfc 100644
> --- a/drivers/i3c/master/dw-i3c-master.c
> +++ b/drivers/i3c/master/dw-i3c-master.c
> @@ -876,6 +876,7 @@ static int dw_i3c_master_daa(struct i3c_master_controller *m)
>  		goto rpm_out;
>  	}
>  	cmd = &xfer->cmds[0];
> +	cmd->rx_len = master->maxdevs;
>  	cmd->cmd_hi = COMMAND_PORT_TRANSFER_ARG;
>  	cmd->cmd_lo = COMMAND_PORT_DEV_COUNT(master->maxdevs - pos) |
>  		      COMMAND_PORT_DEV_INDEX(pos) |
> @@ -888,7 +889,10 @@ static int dw_i3c_master_daa(struct i3c_master_controller *m)
>  	if (!wait_for_completion_timeout(&xfer->comp, XFER_TIMEOUT))
>  		dw_i3c_master_dequeue_xfer(master, xfer);
>  
> -	newdevs = GENMASK(master->maxdevs - cmd->rx_len - 1, 0);
> +	if (cmd->rx_len >= master->maxdevs)
> +		newdevs = 0;
> +	else
> +		newdevs = GENMASK(master->maxdevs - cmd->rx_len - 1, 0);
>  	newdevs &= ~olddevs;
>  
>  	for (pos = 0; pos < master->maxdevs; pos++) {
> -- 
> 2.51.0
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

-- 
linux-i3c mailing list
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^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2026-08-18 21:18 UTC | newest]

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2026-08-14  4:20 [PATCH v2] i3c: dw: reduce do_daa time if there's no client Jisheng Zhang
2026-08-14 16:38 ` Frank Li
2026-08-18 21:18 ` Alexandre Belloni

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