Re: [PATCH] tty: implement a rx led trigger

Pavel Machek
2018-05-03T10:10:47Z

[-- Attachment #1: Type: text/plain, Size: 2835 bytes --]

Hi!

> The trigger fires when data is pushed to the ldisc. This is a bit later
> than the actual receiving of data but has the nice benefit that it
> doesn't need adaption for each driver and isn't in the hot path.
>
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Well, why not, but there certainly should be config option? Because I
really don't see many people wanting to use this trigger.

> diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
> index c996b6859c5e..4d364b77b1a7 100644
> --- a/drivers/tty/tty_buffer.c
> +++ b/drivers/tty/tty_buffer.c
> @@ -17,6 +17,7 @@
> #include <linux/delay.h>
> #include <linux/module.h>
> #include <linux/ratelimit.h>
> +#include <linux/leds.h>
>
>
> #define MIN_TTYB_SIZE 256
> @@ -499,6 +500,7 @@ static void flush_to_ldisc(struct work_struct *work)
> struct tty_buffer *head = buf->head;
> struct tty_buffer *next;
> int count;
> + unsigned long delay = 50 /* ms */;
>
> /* Ldisc or user is trying to gain exclusive access */
> if (atomic_read(&buf->priority))
> @@ -521,6 +523,8 @@ static void flush_to_ldisc(struct work_struct *work)
> continue;
> }
>
> + led_trigger_blink_oneshot(port->led_trigger_rx, &delay, &delay, 0);
> +
> count = receive_buf(port, head, count);
> if (!count)
> break;
> diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
> index 25d736880013..51b78a585417 100644
> --- a/drivers/tty/tty_port.c
> +++ b/drivers/tty/tty_port.c
> @@ -16,6 +16,7 @@
> #include <linux/wait.h>
> #include <linux/bitops.h>
> #include <linux/delay.h>
> +#include <linux/leds.h>
> #include <linux/module.h>
> #include <linux/serdev.h>
>
> @@ -157,6 +158,18 @@ struct device *tty_port_register_device_attr_serdev(struct tty_port *port,
>
> tty_port_link_device(port, driver, index);
>
> + port->led_trigger_rx_name = kasprintf(GFP_KERNEL, "%s%d-rx",
> + driver->name, index);
> + if (!port->led_trigger_rx_name) {
> + pr_err("Failed to allocate trigger name for %s%d\n",
> + driver->name, index);
> + goto skip_trigger;
> + }
> +
> + led_trigger_register_simple(port->led_trigger_rx_name,
> + &port->led_trigger_rx);
> +
> +skip_trigger:
> dev = serdev_tty_port_register(port, device, driver, index);
> if (PTR_ERR(dev) != -ENODEV) {
> /* Skip creating cdev if we registered a serdev device */
> @@ -206,6 +219,9 @@ void tty_port_unregister_device(struct tty_port *port,
> if (ret == 0)
> return;
>
> + led_trigger_unregister_simple(port->led_trigger_rx);

Is it ok to unregister if it was not registered in the first place?

--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]