From 0a6c301a2db2f9af0478a83c15d8ec5cdac65eb9 Mon Sep 17 00:00:00 2001 From: Qipeng Zha Date: Wed, 29 Jul 2015 18:23:32 +0800 Subject: [PATCH] serial: 8250: Auto CTS control by HW if AFE enabled According to DesignWare 8250 spec, if auto flow control mode is enabled, a change in CTS does not cause an interrupt, so sw-assisted CTS flow control mode will not work properly. There reported an GPS firmware download failure issue, and we verified the root cause is, the default sw-assisted CTS flow control mode can not work properly since no interrupt when got CTS signal. This patch is to enable auto CTS mode by defaut if CRTSCTS is enable for DesignWare 8250 controller. Signed-off-by: Huiquan Zhong Signed-off-by: Qipeng Zha Reviewed-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_dw.c | 5 +++++ drivers/tty/serial/8250/8250_pci.c | 4 ++++ 2 files changed, 9 insertions(+) diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c index d48b50641e9a6..8d04ea781de4e 100644 --- a/drivers/tty/serial/8250/8250_dw.c +++ b/drivers/tty/serial/8250/8250_dw.c @@ -257,6 +257,11 @@ static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios, if (!ret) p->uartclk = rate; + + p->status &= ~UPSTAT_AUTOCTS; + if (termios->c_cflag & CRTSCTS) + p->status |= UPSTAT_AUTOCTS; + out: serial8250_do_set_termios(p, termios, old); } diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c index df2e61e206fa0..dd4483f1d3290 100644 --- a/drivers/tty/serial/8250/8250_pci.c +++ b/drivers/tty/serial/8250/8250_pci.c @@ -1417,6 +1417,10 @@ byt_set_termios(struct uart_port *p, struct ktermios *termios, reg |= BYT_PRV_CLK_EN | BYT_PRV_CLK_UPDATE; writel(reg, p->membase + BYT_PRV_CLK); + p->status &= ~UPSTAT_AUTOCTS; + if (termios->c_cflag & CRTSCTS) + p->status |= UPSTAT_AUTOCTS; + serial8250_do_set_termios(p, termios, old); } -- GitLab