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Commit d1c48227 authored by Ji-Ze Hong (Peter Hong)'s avatar Ji-Ze Hong (Peter Hong) Committed by Johan Hovold
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USB: serial: f81534: fix tx error on some baud rate 



The F81532/534 had 4 clocksource 1.846/18.46/14.77/24MHz and baud rates
can be up to 1.5Mbits with 24MHz. But on some baud rate (384~500kps), the
TX side will send the data frame too close to treat frame error on RX
side. This patch will force all TX data frame with delay 1bit gap.

Signed-off-by: default avatarJi-Ze Hong (Peter Hong) <hpeter+linux_kernel@gmail.com>
Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
parent bb543ca2

drivers/usb/serial/f81534.c

+6 −1
Original line number Diff line number Diff line
@@ -131,6 +131,7 @@ 
#define F81534_CLK_24_MHZ		BIT(2)

#define F81534_CLK_14_77_MHZ		(BIT(1) | BIT(2))

#define F81534_CLK_MASK			GENMASK(2, 1)

#define F81534_CLK_TX_DELAY_1BIT	BIT(3)

#define F81534_CLK_RS485_MODE		BIT(4)

#define F81534_CLK_RS485_INVERT		BIT(5)
@@ -1386,7 +1387,11 @@ static int f81534_port_probe(struct usb_serial_port *port) 
	if (!port_priv)

		return -ENOMEM;



	port_priv->shadow_clk = F81534_UART_EN;

	/*

	 * We'll make tx frame error when baud rate from 384~500kps. So we'll

	 * delay all tx data frame with 1bit.

	 */

	port_priv->shadow_clk = F81534_UART_EN | F81534_CLK_TX_DELAY_1BIT;

	spin_lock_init(&port_priv->msr_lock);

	mutex_init(&port_priv->mcr_mutex);

	mutex_init(&port_priv->lcr_mutex);