* [PATCH] ALSA: serial-generic: explicitly disable flow control
@ 2024-09-26 10:44 John Keeping
2024-09-27 8:39 ` Johan Hovold
0 siblings, 1 reply; 2+ messages in thread
From: John Keeping @ 2024-09-26 10:44 UTC (permalink / raw)
To: linux-sound
Cc: John Keeping, Jaroslav Kysela, Takashi Iwai, Johan Hovold,
Greg Kroah-Hartman, Alex Elder, Jonathan Cameron, Lee Jones,
Francesco Dolcini, Jiri Slaby (SUSE), Rob Herring, Daniel Kaehn,
linux-kernel
The serdev subsystem does not specify the default state of flow control
when opening a device. Surveying other drivers using serdev shows the
vast majority of these set flow control explicitly after opening the
device.
MIDI does not use flow control, so ensure it is disabled.
Fixes: 542350509499f ("ALSA: Add generic serial MIDI driver using serial bus API")
Signed-off-by: John Keeping <jkeeping@inmusicbrands.com>
---
sound/drivers/serial-generic.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/sound/drivers/serial-generic.c b/sound/drivers/serial-generic.c
index 36409a56c675e..322b5029ea49f 100644
--- a/sound/drivers/serial-generic.c
+++ b/sound/drivers/serial-generic.c
@@ -139,6 +139,8 @@ static int snd_serial_generic_ensure_serdev_open(struct snd_serial_generic *drvd
drvdata->baudrate, drvdata->card->shortname, actual_baud);
}
+ serdev_device_set_flow_control(drvdata->serdev, false);
+
return 0;
}
--
2.46.2
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] ALSA: serial-generic: explicitly disable flow control
2024-09-26 10:44 [PATCH] ALSA: serial-generic: explicitly disable flow control John Keeping
@ 2024-09-27 8:39 ` Johan Hovold
0 siblings, 0 replies; 2+ messages in thread
From: Johan Hovold @ 2024-09-27 8:39 UTC (permalink / raw)
To: John Keeping
Cc: linux-sound, Jaroslav Kysela, Takashi Iwai, Greg Kroah-Hartman,
Alex Elder, Jonathan Cameron, Lee Jones, Francesco Dolcini,
Jiri Slaby (SUSE), Rob Herring, Daniel Kaehn, linux-kernel
On Thu, Sep 26, 2024 at 11:44:03AM +0100, John Keeping wrote:
> The serdev subsystem does not specify the default state of flow control
> when opening a device.
This bit isn't correct as serdev enables hardware flow control (CRTSCTS)
by default on open() (see ttyport_open()).
> Surveying other drivers using serdev shows the
> vast majority of these set flow control explicitly after opening the
> device.
>
> MIDI does not use flow control, so ensure it is disabled.
Johan
^ permalink raw reply [flat|nested] 2+ messages in thread
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