linux-kernel - [PATCH v2 1/1] i3c: master: Avoid sending DISEC command with old device address.

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Message-ID: <20240820151917.3904956-1-ravindra.yashvant.shinde@nxp.com>
Date: Tue, 20 Aug 2024 20:49:17 +0530
From: Ravindra Yashvant Shinde <ravindra.yashvant.shinde@....com>
To: Alexandre Belloni <alexandre.belloni@...tlin.com>,
	linux-i3c@...ts.infradead.org (moderated list:I3C SUBSYSTEM),
	linux-kernel@...r.kernel.org (open list)
Cc: imx@...ts.linux.dev,
	Frank.Li@....com,
	Ravindra Yashvant Shinde <ravindra.yashvant.shinde@....com>
Subject: [PATCH v2 1/1] i3c: master: Avoid sending DISEC command with old device address.

When a new device hotjoins, a new dynamic address is assigned.
i3c_master_add_i3c_dev_locked() identifies that the device was previously
attached to the bus and locates the olddev.

i3c_master_add_i3c_dev_locked()
{
    ...
    olddev = i3c_master_search_i3c_dev_duplicate(newdev);
    ...
    if (olddev) {
        enable_ibi = true;
        ...
    }
    i3c_dev_free_ibi_locked(olddev);
    ^^^^^^^^
    This function internally calls i3c_dev_disable_ibi_locked(addr)
    function causing to send DISEC command with old Address.

    The olddev should not receive any commands on the i3c bus as it
    does not exist and has been assigned a new address. This will
    result in NACK or timeout. So, update the olddev->ibi->enabled
    flag to false to avoid DISEC with OldAddr.
    ...
}

Signed-off-by: Ravindra Yashvant Shinde <ravindra.yashvant.shinde@....com>
---
change from v1 to v2
- Fixed the author name.
- Unconditional set to the false & added some comments.
---
 drivers/i3c/master.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index 7028f03c2c42..0dd8d1c28d58 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -2043,7 +2043,14 @@ int i3c_master_add_i3c_dev_locked(struct i3c_master_controller *master,
 				enable_ibi = true;
 				i3c_dev_disable_ibi_locked(olddev);
 			}
-
+			/*
+			 * The olddev should not receive any commands on the
+			 * i3c bus as it does not exist and has been assigned
+			 * a new address. This will result in NACK or timeout.
+			 * So, update the olddev->ibi->enabled flag to false
+			 * to avoid DISEC with OldAddr.
+			 */
+			olddev->ibi->enabled = false;
 			i3c_dev_free_ibi_locked(olddev);
 		}
 		mutex_unlock(&olddev->ibi_lock);
-- 
2.46.0