linux-kernel - [PATCH] i3c: master: svc: fix signed/unsigned mismatch in dynamic address assignment

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Message-Id: <20250309164314.15039-1-qasdev00@gmail.com>
Date: Sun,  9 Mar 2025 16:43:14 +0000
From: Qasim Ijaz <qasdev00@...il.com>
To: miquel.raynal@...tlin.com,
	Frank.Li@....com,
	alexandre.belloni@...tlin.com
Cc: linux-i3c@...ts.infradead.org,
	imx@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: [PATCH] i3c: master: svc: fix signed/unsigned mismatch in dynamic address assignment

svc_i3c_master_do_daa_locked() declares dyn_addr as an unsigned int 
however it initialises it with i3c_master_get_free_addr() which 
returns a signed int type and then attempts to check if dyn_addr is 
less than 0. Unsigned integers cannot be less than 0, so the check 
is essentially redundant. Furthermore i3c_master_get_free_addr() 
could return -ENOMEM which an unsigned int cannot store.

Fix this by capturing the return value of i3c_master_get_free_addr() 
in a signed int ‘dyn_addr_ret’. If that value is negative, return 
an error. Otherwise, assign it to the unsigned int ‘dyn_addr’ once 
we know it’s valid.

Fixes: 4008a74e0f9b ("i3c: master: svc: Fix npcm845 FIFO empty issue")
Signed-off-by: Qasim Ijaz <qasdev00@...il.com>
---
 drivers/i3c/master/svc-i3c-master.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
index f22fb9e75142..eea08f00d7ce 100644
--- a/drivers/i3c/master/svc-i3c-master.c
+++ b/drivers/i3c/master/svc-i3c-master.c
@@ -998,9 +998,11 @@ static int svc_i3c_master_do_daa_locked(struct svc_i3c_master *master,
 			 * filling within a few hundred nanoseconds, which is significantly
 			 * faster compared to the 64 SCL clock cycles.
 			 */
-			dyn_addr = i3c_master_get_free_addr(&master->base, last_addr + 1);
-			if (dyn_addr < 0)
+			int dyn_addr_ret = i3c_master_get_free_addr(&master->base, last_addr + 1);
+
+			if (dyn_addr_ret < 0)
 				return -ENOSPC;
+			dyn_addr = dyn_addr_ret;

 			writel(dyn_addr, master->regs + SVC_I3C_MWDATAB);

-- 
2.39.5