| Message ID | 1509691191-3850-1-git-send-email-wilson.lee@ni.com |
|---|---|
| State | Accepted |
| Commit | b12907f279ca25acb79838ede89905ff5c1dfcc5 |
| Delegated to: | Tom Rini |
| Headers | show |
| Series | [U-Boot] serial: nulldev: Implement "pending" function to fix tstc return "true" | expand |
On Thu, Nov 02, 2017 at 11:39:51PM -0700, Wilson Lee wrote: > In U-boot, serial_tstc was use to determine is there have a character in > serial console that pending for read. If there is no "pending" function > implemented in serial driver, the serial-uclass will return "true(1)" > to indicate there have a character pending to read. > > Thus, read a character from nulldev serial will result in continuous > getting -EAGAIN return which might lead system to hang. > > This commit is to fix a bug in nulldev serial which implement "pending" > function in nulldev serial to always indicate there is no character in > console that pending for read. > > Signed-off-by: Wilson Lee <wilson.lee@ni.com> > Cc: Joe Hershberger <joe.hershberger@ni.com> > Cc: Keng Soon Cheah <keng.soon.cheah@ni.com> > Cc: Chen Yee Chew <chen.yee.chew@ni.com> > Cc: Bin Meng <bmeng.cn@gmail.com> Applied to u-boot/master, thanks!
diff --git a/drivers/serial/serial_nulldev.c b/drivers/serial/serial_nulldev.c index 0768308..17b2310 100644 --- a/drivers/serial/serial_nulldev.c +++ b/drivers/serial/serial_nulldev.c @@ -18,6 +18,11 @@ static int nulldev_serial_getc(struct udevice *dev) return -EAGAIN; } +static int nulldev_serial_pending(struct udevice *dev, bool input) +{ + return 0; +} + static int nulldev_serial_input(struct udevice *dev) { return 0; @@ -36,6 +41,7 @@ static const struct udevice_id nulldev_serial_ids[] = { const struct dm_serial_ops nulldev_serial_ops = { .putc = nulldev_serial_putc, + .pending = nulldev_serial_pending, .getc = nulldev_serial_getc, .setbrg = nulldev_serial_setbrg, };
In U-boot, serial_tstc was use to determine is there have a character in serial console that pending for read. If there is no "pending" function implemented in serial driver, the serial-uclass will return "true(1)" to indicate there have a character pending to read. Thus, read a character from nulldev serial will result in continuous getting -EAGAIN return which might lead system to hang. This commit is to fix a bug in nulldev serial which implement "pending" function in nulldev serial to always indicate there is no character in console that pending for read. Signed-off-by: Wilson Lee <wilson.lee@ni.com> Cc: Joe Hershberger <joe.hershberger@ni.com> Cc: Keng Soon Cheah <keng.soon.cheah@ni.com> Cc: Chen Yee Chew <chen.yee.chew@ni.com> Cc: Bin Meng <bmeng.cn@gmail.com> --- drivers/serial/serial_nulldev.c | 6 ++++++ 1 file changed, 6 insertions(+)