linux-kernel - [PATCH] serial: tegra: Fix a mask operation that is always true

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Message-Id: <20210426105514.23268-1-colin.king@canonical.com>
Date:   Mon, 26 Apr 2021 11:55:14 +0100
From:   Colin King <colin.king@...onical.com>
To:     Laxman Dewangan <ldewangan@...dia.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Krishna Yarlagadda <kyarlagadda@...dia.com>,
        Shardar Shariff Md <smohammed@...dia.com>,
        linux-serial@...r.kernel.org, linux-tegra@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] serial: tegra: Fix a mask operation that is always true

From: Colin Ian King <colin.king@...onical.com>

Currently the expression lsr | UART_LSR_TEMT is always true and
this seems suspect. I believe the intent was to mask lsr with UART_LSR_TEMT
to check that bit, so the expression should be using the & operator
instead. Fix this.

Fixes: b9c2470fb150 ("serial: tegra: flush the RX fifo on frame error")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/tty/serial/serial-tegra.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
index bbae072a125d..222032792d6c 100644
--- a/drivers/tty/serial/serial-tegra.c
+++ b/drivers/tty/serial/serial-tegra.c
@@ -338,7 +338,7 @@ static void tegra_uart_fifo_reset(struct tegra_uart_port *tup, u8 fcr_bits)
 
 	do {
 		lsr = tegra_uart_read(tup, UART_LSR);
-		if ((lsr | UART_LSR_TEMT) && !(lsr & UART_LSR_DR))
+		if ((lsr & UART_LSR_TEMT) && !(lsr & UART_LSR_DR))
 			break;
 		udelay(1);
 	} while (--tmout);
-- 
2.30.2