Hi,

* Jiri Slaby [off-list ref] [200818 08:24]:

On 17. 08. 20, 15:54, Tony Lindgren wrote:

quoted

If write returns zero we currently end up removing the message
from the queue. Instead of removing the message, we want to just
break out of the loop just like we already do for error codes.

When exactly does the only writer (gsmld_output) return zero for
non-zero len parameter?

I ran into this when testing with the WIP serial core PM runtime
changes from Andy Shevchenko earlier. If there are also other
cases where we have serial drivers return 0, I don't know about
them.

Basically with the WIP serial core changes, if the open serial port
is in PM runtime suspended state with it's autosuspend_delay_ms
expired, we have write return 0 and just wake up the serial device
on TX.

I don't think there's much anything else we can currently do there
in the PM runtime suspended case as we want to get rid of the
remaining pm_runtime_irq_safe() dependencies as it takes a permanent
usage count on the parent device.

Regards,

Tony

quoted

Signed-off-by: Tony Lindgren <tony@atomide.com>
---
 drivers/tty/n_gsm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c

@@ -691,7 +691,8 @@ static void gsm_data_kick(struct gsm_mux *gsm, struct gsm_dlci *dlci)
 			print_hex_dump_bytes("gsm_data_kick: ",
 					     DUMP_PREFIX_OFFSET,
 					     gsm->txframe, len);
-		if (gsm->output(gsm, gsm->txframe, len) < 0)
+
+		if (gsm->output(gsm, gsm->txframe, len) <= 0)
 			break;
 		/* FIXME: Can eliminate one SOF in many more cases */
 		gsm->tx_bytes -= msg->len;

thanks,
-- 
js