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From: Jisheng Zhang <jszhang@kernel.org>
To: Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Frank Li <Frank.Li@nxp.com>
Cc: linux-i3c@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH v3] i3c: dw: reduce do_daa time if there's no client
Date: Wed, 19 Aug 2026 12:48:33 +0800	[thread overview]
Message-ID: <20260819044833.32611-1-jszhang@kernel.org> (raw)

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 the existing rx_count >= maxdevs check then reports an empty bus.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
---

since v2:
 - rebase on the lastest i3c/next
 - collect Reviewed-by tag

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 | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c
index 0a3799a4ce87..4563d8761ba0 100644
--- a/drivers/i3c/master/dw-i3c-master.c
+++ b/drivers/i3c/master/dw-i3c-master.c
@@ -921,6 +921,7 @@ 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) |
-- 
2.51.0


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WARNING: multiple messages have this Message-ID (diff)
From: Jisheng Zhang <jszhang@kernel.org>
To: Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Frank Li <Frank.Li@nxp.com>
Cc: linux-i3c@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH v3] i3c: dw: reduce do_daa time if there's no client
Date: Wed, 19 Aug 2026 12:48:33 +0800	[thread overview]
Message-ID: <20260819044833.32611-1-jszhang@kernel.org> (raw)

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 the existing rx_count >= maxdevs check then reports an empty bus.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
---

since v2:
 - rebase on the lastest i3c/next
 - collect Reviewed-by tag

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 | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c
index 0a3799a4ce87..4563d8761ba0 100644
--- a/drivers/i3c/master/dw-i3c-master.c
+++ b/drivers/i3c/master/dw-i3c-master.c
@@ -921,6 +921,7 @@ 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) |
-- 
2.51.0


             reply	other threads:[~2026-08-19  5:08 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-19  4:48 Jisheng Zhang [this message]
2026-08-19  4:48 ` [PATCH v3] i3c: dw: reduce do_daa time if there's no client Jisheng Zhang
2026-08-19  5:22 ` sashiko-bot

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