Re: [PATCH v2] input: API for Setting a Timestamp from a Driver

Dmitry Torokhov
2019-07-25T05:27:37Z

Hi Atif,

On Thu, Jul 18, 2019 at 12:41:33PM -0700, Atif Niyaz wrote:
> @@ -150,16 +143,19 @@ static void __evdev_flush_queue(struct evdev_client *client, unsigned int type)
> static void __evdev_queue_syn_dropped(struct evdev_client *client)
> {
> struct input_event ev;
> - ktime_t time;
> struct timespec64 ts;
> + ktime_t *time = input_get_timestamp(client->evdev->handle.dev);
>
> - time = client->clk_type == EV_CLK_REAL ?
> - ktime_get_real() :
> - client->clk_type == EV_CLK_MONO ?
> - ktime_get() :
> - ktime_get_boottime();
> + switch (client->clk_type) {
> + case INPUT_CLK_REAL:
> + case INPUT_CLK_MONO:
> + ts = ktime_to_timespec64(time[client->clk_type]);
> + break;
> + default:
> + ts = ktime_to_timespec64(time[INPUT_CLK_BOOT]);
> + break;

Since we trust client->clk_type be valid in evdev_event() we can also
trust it here. I replaced the switch statement with:

ts = ktime_to_timespec64(ev_time[client->clkk_type]);

> + }
>
> - ts = ktime_to_timespec64(time);
> ev.input_event_sec = ts.tv_sec;
> ev.input_event_usec = ts.tv_nsec / NSEC_PER_USEC;
> ev.type = EV_SYN;
> @@ -185,21 +181,21 @@ static void evdev_queue_syn_dropped(struct evdev_client *client)
> spin_unlock_irqrestore(&client->buffer_lock, flags);
> }
>
> -static int evdev_set_clk_type(struct evdev_client *client, unsigned int clkid)
> +static int evdev_set_clk_type(struct evdev_client *client, clockid_t clkid)

The data passed to evdev_set_clk_type() is an integer with values that
coincide with the enum's values, so I kept the type of parameter as it
was.

> +/**
> + * input_set_timestamp - set timestamp for input events
> + * @dev: input device to set timestamp for
> + * @timestamp: the time at which the event has occurred
> + * in CLOCK_MONOTONIC
> + *
> + * This function is intended to provide to the input system a more
> + * accurate time of when an event actually occurred. The driver should
> + * call this function as soon as a timestamp is acquired ensuring
> + * clock conversions in input_set_timestamp are done correctly.
> + *
> + * The system entering a suspend between timestamp acquisition and
> + * calling input_set_timestamp can result in inaccurate conversions.
> + *
> + */
> +static inline void input_set_timestamp(struct input_dev *dev,
> + ktime_t timestamp)
> +{
> + dev->timestamp[INPUT_CLK_MONO] = timestamp;
> + dev->timestamp[INPUT_CLK_REAL] = ktime_mono_to_real(timestamp);
> + dev->timestamp[INPUT_CLK_BOOT] = ktime_mono_to_any(
> + timestamp, TK_OFFS_BOOT);
> +}

I moved this input input.c, together with input_get_timestamp().

Applied, thank you.

--
Dmitry