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authorBen Dooks <ben.dooks@codethink.co.uk>2015-11-18 14:41:12 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-12-13 19:59:48 -0800
commit00661dd855b5b174aa176a9ab9437d86ef4f8f1a (patch)
tree1249ecfd5759347eb13ccf2cc6804cbf871012e5 /drivers/tty
parent1bc1f17b7f1ca320b389622e3c7fbf4ee8991f61 (diff)
ARM: meson: serial: don't reset port on uart startup
When the uart startup entry is called, do not reset the port as this could cause issues with anything left in the FIFO from a previous operation such as a console write. Move the hardware reset to probe time and simply clear the errors before enabling the port. This fixes the issue where the console could become corrupted as there where characters left in the output or output fifo when a user process such as systemd would open/close the uart to transmit characters. For example, you get: [ 3.252263] systemd[1]: Dete instead of: [ 3.338801] systemd[1]: Detected architecture arm. Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk> Tested-by: Carlo Caione <carlo@endlessm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/serial/meson_uart.c21
1 files changed, 19 insertions, 2 deletions
diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
index b9f0829ceda1..b87eb97e5e7a 100644
--- a/drivers/tty/serial/meson_uart.c
+++ b/drivers/tty/serial/meson_uart.c
@@ -241,10 +241,9 @@ static const char *meson_uart_type(struct uart_port *port)
return (port->type == PORT_MESON) ? "meson_uart" : NULL;
}
-static int meson_uart_startup(struct uart_port *port)
+static void meson_uart_reset(struct uart_port *port)
{
u32 val;
- int ret = 0;
val = readl(port->membase + AML_UART_CONTROL);
val |= (AML_UART_RX_RST | AML_UART_TX_RST | AML_UART_CLR_ERR);
@@ -252,6 +251,18 @@ static int meson_uart_startup(struct uart_port *port)
val &= ~(AML_UART_RX_RST | AML_UART_TX_RST | AML_UART_CLR_ERR);
writel(val, port->membase + AML_UART_CONTROL);
+}
+
+static int meson_uart_startup(struct uart_port *port)
+{
+ u32 val;
+ int ret = 0;
+
+ val = readl(port->membase + AML_UART_CONTROL);
+ val |= AML_UART_CLR_ERR;
+ writel(val, port->membase + AML_UART_CONTROL);
+ val &= ~AML_UART_CLR_ERR;
+ writel(val, port->membase + AML_UART_CONTROL);
val |= (AML_UART_RX_EN | AML_UART_TX_EN);
writel(val, port->membase + AML_UART_CONTROL);
@@ -581,6 +592,12 @@ static int meson_uart_probe(struct platform_device *pdev)
meson_ports[pdev->id] = port;
platform_set_drvdata(pdev, port);
+ /* reset port before registering (and possibly registering console) */
+ if (meson_uart_request_port(port) >= 0) {
+ meson_uart_reset(port);
+ meson_uart_release_port(port);
+ }
+
ret = uart_add_one_port(&meson_uart_driver, port);
if (ret)
meson_ports[pdev->id] = NULL;