tty_schedule_flip() would schedule a thread that would call flush_to_ldisc().
If tty_buffer_request_room() gets called prior to that thread running --
which is likely in this loop in hvc_poll(), it would set the active flag
in the tty buffer and consequently flush_to_ldisc() would ignore it.
The result is that input on the hvc console is not processed.
This fix calls tty_flip_buffer_push (and flags the tty as
"low_latency"). The push to the ldisc thus happens synchronously.
Signed-off-by: Michal Ostrowski <[email protected]>
---
drivers/char/hvc_console.c | 9 ++++++---
1 files changed, 6 insertions(+), 3 deletions(-)
1d719e2972f0c02d62a428aa84ca60793ad79666
diff --git a/drivers/char/hvc_console.c b/drivers/char/hvc_console.c
index 1994a92..67f368f 100644
--- a/drivers/char/hvc_console.c
+++ b/drivers/char/hvc_console.c
@@ -335,6 +335,8 @@ static int hvc_open(struct tty_struct *t
} /* else count == 0 */
tty->driver_data = hp;
+ tty->low_latency = 1; /* Makes flushes to ldisc synchronous. */
+
hp->tty = tty;
/* Save for request_irq outside of spin_lock. */
irq = hp->irq;
@@ -633,9 +635,6 @@ static int hvc_poll(struct hvc_struct *h
tty_insert_flip_char(tty, buf[i], 0);
}
- if (count)
- tty_schedule_flip(tty);
-
/*
* Account for the total amount read in one loop, and if above
* 64 bytes, we do a quick schedule loop to let the tty grok
@@ -656,6 +655,10 @@ static int hvc_poll(struct hvc_struct *h
bail:
spin_unlock_irqrestore(&hp->lock, flags);
+ if (read_total) {
+ tty_flip_buffer_push(tty);
+ }
+
return poll_mask;
}
--
1.1.4.g0b63-dirty
-
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