The ft260 chip enters power save mode after 5 seconds of being in idle
state. It causes the data loss on the Rx line. The implemented workaround
sends a dummy report every 4.8 seconds, preventing the chip from entering
the power save mode. But the baud rates below 4800 work fine without a
wakeup workaround.
This commit makes the wakeup workaround activation dependent on the UART
rate, allowing entering the power saving mode for the UART rates below
4800 bauds.
[11238.542841] ft260_uart_wakeup_workaraund_enable: Activate wakeup workaround
[11238.542843] ft260_uart_change_speed: Configured termios: flow control: 0, baudrate: 9600,
[11238.542845] ft260_uart_change_speed: data_bit: 8, parity: 0, stop_bit: 0, breaking: 0
[11238.543671] ft260_uart_wakeup_workaraund_enable: Deactivate wakeup workaround
[11238.543683] ft260_uart_change_speed: Configured termios: flow control: 0, baudrate: 4800,
[11238.543684] ft260_uart_change_speed: data_bit: 8, parity: 0, stop_bit: 0, breaking: 0
Signed-off-by: Michael Zaidman <michael.zaidman@xxxxxxxxx>
---
drivers/hid/hid-ft260.c | 48 +++++++++++++++++++++++++++++++----------
1 file changed, 37 insertions(+), 11 deletions(-)
diff --git a/drivers/hid/hid-ft260.c b/drivers/hid/hid-ft260.c
index 19599e64c6be..b24998092d22 100644
--- a/drivers/hid/hid-ft260.c
+++ b/drivers/hid/hid-ft260.c
@@ -296,6 +296,8 @@ enum {
FT260_CFG_BAUD_MAX = 12000000,
};
+#define FT260_UART_EN_PW_SAVE_BAUD 4800
+
static const struct hid_device_id ft260_devices[] = {
{ HID_USB_DEVICE(USB_VENDOR_ID_FUTURE_TECHNOLOGY,
USB_DEVICE_ID_FT260) },
@@ -1056,6 +1058,15 @@ static const struct attribute_group ft260_attr_group = {
static DEFINE_MUTEX(ft260_uart_list_lock);
static LIST_HEAD(ft260_uart_device_list);
+static void ft260_uart_wakeup(struct ft260_device *dev);
+
+static void ft260_uart_wakeup_workaraund_enable(struct ft260_device *port,
+ bool enable)
+{
+ port->reschedule_work = enable;
+ ft260_dbg("%s wakeup workaround", enable ? "Activate" : "Deactivate");
+}
+
static struct ft260_device *ft260_dev_by_index(int index)
{
struct ft260_device *port;
@@ -1108,7 +1119,7 @@ static void ft260_uart_port_remove(struct ft260_device *port)
spin_unlock(&port->write_lock);
mutex_lock(&port->port.mutex);
- port->reschedule_work = false;
+ ft260_uart_wakeup_workaraund_enable(port, false);
tty_port_tty_hangup(&port->port, false);
mutex_unlock(&port->port.mutex);
@@ -1266,8 +1277,11 @@ static int ft260_uart_change_speed(struct ft260_device *port,
struct hid_device *hdev = port->hdev;
unsigned int baud;
struct ft260_configure_uart_request req;
+ bool wakeup_workaraund = false;
int ret;
+ ft260_uart_wakeup(port);
+
memset(&req, 0, sizeof(req));
req.report = FT260_SYSTEM_SETTINGS;
@@ -1309,6 +1323,12 @@ static int ft260_uart_change_speed(struct ft260_device *port,
tty_encode_baud_rate(tty, baud, baud);
tty_kref_put(tty);
}
+
+ if (baud > FT260_UART_EN_PW_SAVE_BAUD)
+ wakeup_workaraund = true;
+
+ ft260_uart_wakeup_workaraund_enable(port, wakeup_workaraund);
+
put_unaligned_le32(cpu_to_le32(baud), &req.baudrate);
if (termios->c_cflag & CRTSCTS)
@@ -1435,13 +1455,13 @@ static const struct tty_operations ft260_uart_ops = {
/* The FT260 has a "power saving mode" that causes the device to switch
* to a 30 kHz oscillator if there's no activity for 5 seconds.
- * Unfortunately this mode can only be disabled by reprogramming
+ * Unfortunately, this mode can only be disabled by reprogramming
* internal fuses, which requires an additional programming voltage.
*
- * One effect of this mode is to cause data loss on a fast UART that
- * transmits after being idle for longer than 5 seconds. We work around
- * this by sending a dummy report at least once per 4 seconds if the
- * UART is in use.
+ * One effect of this mode is to cause data loss on an Rx line at baud
+ * rates higher than 4800 after being idle for longer than 5 seconds.
+ * We work around this by sending a dummy report at least once per 4.8
+ * seconds if the UART is in use.
*/
static void ft260_uart_start_wakeup(struct timer_list *t)
{
@@ -1455,10 +1475,8 @@ static void ft260_uart_start_wakeup(struct timer_list *t)
}
}
-static void ft260_uart_do_wakeup(struct work_struct *work)
+static void ft260_uart_wakeup(struct ft260_device *dev)
{
- struct ft260_device *dev =
- container_of(work, struct ft260_device, wakeup_work);
struct ft260_get_chip_version_report version;
int ret;
@@ -1472,12 +1490,20 @@ static void ft260_uart_do_wakeup(struct work_struct *work)
}
}
+static void ft260_uart_do_wakeup(struct work_struct *work)
+{
+ struct ft260_device *dev =
+ container_of(work, struct ft260_device, wakeup_work);
+
+ ft260_uart_wakeup(dev);
+}
+
static void ft260_uart_shutdown(struct tty_port *tport)
{
struct ft260_device *port =
container_of(tport, struct ft260_device, port);
- port->reschedule_work = false;
+ ft260_uart_wakeup_workaraund_enable(port, false);
}
static int ft260_uart_activate(struct tty_port *tport, struct tty_struct *tty)
@@ -1575,7 +1601,7 @@ static int ft260_uart_probe(struct hid_device *hdev, struct ft260_device *dev)
INIT_WORK(&dev->wakeup_work, ft260_uart_do_wakeup);
// FIXME: Do I need that if I have cancel_work_sync?
// FIXME: are all kfifo access secured by lock? with irq or not?
- dev->reschedule_work = true;
+ ft260_uart_wakeup_workaraund_enable(dev, true);
/* Work not started at this point */
timer_setup(&dev->wakeup_timer, ft260_uart_start_wakeup, 0);
--
2.40.1
