i3c: master: svc: fix possible assignment of the same address to two devices

svc_i3c_master_do_daa() {
    ...
    for (i = 0; i < dev_nb; i++) {
        ret = i3c_master_add_i3c_dev_locked(m, addrs[i]);
        if (ret)
            goto rpm_out;
    }
}

If two devices (A and B) are detected in DAA and address 0xa is assigned to
device A and 0xb to device B, a failure in i3c_master_add_i3c_dev_locked()
for device A (addr: 0xa) could prevent device B (addr: 0xb) from being
registered on the bus. The I3C stack might still consider 0xb a free
address. If a subsequent Hotjoin occurs, 0xb might be assigned to Device A,
causing both devices A and B to use the same address 0xb, violating the I3C
specification.

The return value for i3c_master_add_i3c_dev_locked() should not be checked
because subsequent steps will scan the entire I3C bus, independent of
whether i3c_master_add_i3c_dev_locked() returns success.

If device A registration fails, there is still a chance to register device
B. i3c_master_add_i3c_dev_locked() can reset DAA if a failure occurs while
retrieving device information.

Cc: stable@kernel.org
Fixes: 317bacf960a4 ("i3c: master: add enable(disable) hot join in sys entry")
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Link: https://lore.kernel.org/r/20241002-svc-i3c-hj-v6-6-7e6e1d3569ae@nxp.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
index 7ef7e50..e9c8e34 100644 (file)
--- a/drivers/i3c/master/svc-i3c-master.c
+++ b/drivers/i3c/master/svc-i3c-master.c
@@ -1103,12 +1103,27 @@ static int svc_i3c_master_do_daa(struct i3c_master_controller *m)
        if (ret)
                goto rpm_out;
 
-       /* Register all devices who participated to the core */
-       for (i = 0; i < dev_nb; i++) {
-               ret = i3c_master_add_i3c_dev_locked(m, addrs[i]);
-               if (ret)
-                       goto rpm_out;
-       }
+       /*
+        * Register all devices who participated to the core
+        *
+        * If two devices (A and B) are detected in DAA and address 0xa is assigned to
+        * device A and 0xb to device B, a failure in i3c_master_add_i3c_dev_locked()
+        * for device A (addr: 0xa) could prevent device B (addr: 0xb) from being
+        * registered on the bus. The I3C stack might still consider 0xb a free
+        * address. If a subsequent Hotjoin occurs, 0xb might be assigned to Device A,
+        * causing both devices A and B to use the same address 0xb, violating the I3C
+        * specification.
+        *
+        * The return value for i3c_master_add_i3c_dev_locked() should not be checked
+        * because subsequent steps will scan the entire I3C bus, independent of
+        * whether i3c_master_add_i3c_dev_locked() returns success.
+        *
+        * If device A registration fails, there is still a chance to register device
+        * B. i3c_master_add_i3c_dev_locked() can reset DAA if a failure occurs while
+        * retrieving device information.
+        */
+       for (i = 0; i < dev_nb; i++)
+               i3c_master_add_i3c_dev_locked(m, addrs[i]);
 
        /* Configure IBI auto-rules */
        ret = svc_i3c_update_ibirules(master);