linux-kernel - [PATCH AUTOSEL 4.4 51/64] tty: serial: samsung: Correct clock selection logic

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 17 Sep 2020 22:16:30 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Jonathan Bakker <xc-racer2@...e.ca>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Sasha Levin <sashal@...nel.org>, linux-serial@...r.kernel.org
Subject: [PATCH AUTOSEL 4.4 51/64] tty: serial: samsung: Correct clock selection logic

From: Jonathan Bakker <xc-racer2@...e.ca>

[ Upstream commit 7d31676a8d91dd18e08853efd1cb26961a38c6a6 ]

Some variants of the samsung tty driver can pick which clock
to use for their baud rate generation.  In the DT conversion,
a default clock was selected to be used if a specific one wasn't
assigned and then a comparison of which clock rate worked better
was done.  Unfortunately, the comparison was implemented in such
a way that only the default clock was ever actually compared.
Fix this by iterating through all possible clocks, except when a
specific clock has already been picked via clk_sel (which is
only possible via board files).

Signed-off-by: Jonathan Bakker <xc-racer2@...e.ca>
Reviewed-by: Krzysztof Kozlowski <krzk@...nel.org>
Link: https://lore.kernel.org/r/BN6PR04MB06604E63833EA41837EBF77BA3A30@BN6PR04MB0660.namprd04.prod.outlook.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/tty/serial/samsung.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index 70a51d0bc6044..42aa37515e9bd 100644
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -1151,14 +1151,14 @@ static unsigned int s3c24xx_serial_getclk(struct s3c24xx_uart_port *ourport,
 	struct s3c24xx_uart_info *info = ourport->info;
 	struct clk *clk;
 	unsigned long rate;
-	unsigned int cnt, baud, quot, clk_sel, best_quot = 0;
+	unsigned int cnt, baud, quot, best_quot = 0;
 	char clkname[MAX_CLK_NAME_LENGTH];
 	int calc_deviation, deviation = (1 << 30) - 1;
 
-	clk_sel = (ourport->cfg->clk_sel) ? ourport->cfg->clk_sel :
-			ourport->info->def_clk_sel;
 	for (cnt = 0; cnt < info->num_clks; cnt++) {
-		if (!(clk_sel & (1 << cnt)))
+		/* Keep selected clock if provided */
+		if (ourport->cfg->clk_sel &&
+			!(ourport->cfg->clk_sel & (1 << cnt)))
 			continue;
 
 		sprintf(clkname, "clk_uart_baud%d", cnt);
-- 
2.25.1