linux-kernel - [PATCH] Revert "serial: 8250: Fix max baud limit in generic 8250 port"

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Date:   Tue, 30 Jun 2020 16:42:11 -0700
From:   Daniel Winkler <danielwinkler@...gle.com>
To:     linux-serial@...r.kernel.org, linux-mediatek@...ts.infradead.org
Cc:     chromeos-bluetooth-upstreaming 
        <chromeos-bluetooth-upstreaming@...omium.org>,
        Daniel Winkler <danielwinkler@...gle.com>,
        Aaron Sierra <asierra@...-inc.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, Lukas Wunner <lukas@...ner.de>,
        Vignesh Raghavendra <vigneshr@...com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] Revert "serial: 8250: Fix max baud limit in generic 8250 port"

This reverts commit 0eeaf62981ecc79e8395ca8caa1570eaf3a12257.

The change regresses the QCA6174A-3 bluetooth chip, preventing
firmware from being properly loaded. We have verified that without
this patch, the chip works as intended.

Signed-off-by: Daniel Winkler <danielwinkler@...gle.com>
---

 drivers/tty/serial/8250/8250_port.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 1632f7d25acca..e057c65ac1580 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -2618,8 +2618,6 @@ static unsigned int serial8250_get_baud_rate(struct uart_port *port,
 					     struct ktermios *termios,
 					     struct ktermios *old)
 {
-	unsigned int tolerance = port->uartclk / 100;
-
 	/*
 	 * Ask the core to calculate the divisor for us.
 	 * Allow 1% tolerance at the upper limit so uart clks marginally
@@ -2628,7 +2626,7 @@ static unsigned int serial8250_get_baud_rate(struct uart_port *port,
 	 */
 	return uart_get_baud_rate(port, termios, old,
 				  port->uartclk / 16 / UART_DIV_MAX,
-				  (port->uartclk + tolerance) / 16);
+				  port->uartclk);
 }
 
 void
-- 
2.27.0.212.ge8ba1cc988-goog