On Thu, Dec 18, 2014 at 03:03:26AM +0530, Aniroop Mathur wrote:
> Hello Mr. Torokhov,
>
> On Wed, Dec 17, 2014 at 11:50 PM, Dmitry Torokhov
> <dmitry.torokhov@xxxxxxxxx> wrote:
> > Hi Aniroop,
> >
> > On Tue, Dec 16, 2014 at 10:26:34PM +0530, Aniroop Mathur wrote:
> >> This patch adds support for CLOCK_BOOTTIME for input event timestamp.
> >> CLOCK_BOOTTIME includes suspend time, so it would allow aplications
> >> to get correct time difference between two events even when system
> >> resumes from suspend state.
> >>
> >> Signed-off-by: Aniroop Mathur <a.mathur@xxxxxxxxxxx>
> >> ---
> >> drivers/input/evdev.c | 33 +++++++++++++++++++++------------
> >> 1 file changed, 21 insertions(+), 12 deletions(-)
> >>
> >> diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
> >> index de05545..7825794 100644
> >> --- a/drivers/input/evdev.c
> >> +++ b/drivers/input/evdev.c
> >> @@ -28,6 +28,13 @@
> >> #include <linux/cdev.h>
> >> #include "input-compat.h"
> >>
> >> +enum clock_type {
> >> + REAL = 0,
> >> + MONO,
> >> + BOOT,
> >> + CLK_MAX
> >> +};
> >> +
> >> struct evdev {
> >> int open;
> >> struct input_handle handle;
> >> @@ -108,8 +115,9 @@ static void evdev_queue_syn_dropped(struct evdev_client *client)
> >> struct input_event ev;
> >> ktime_t time;
> >>
> >> - time = (client->clkid == CLOCK_MONOTONIC) ?
> >> - ktime_get() : ktime_get_real();
> >> + time = (client->clkid == CLOCK_REALTIME) ?
> >> + ktime_get_real() : (client->clkid == CLOCK_MONOTONIC) ?
> >> + ktime_get() : ktime_get_boottime();
> >>
>
> Is this okay ?
> To improve readabilty,
> how about adding a new funtion to get time depending upon clkid like below ?
> time = get_clk_time(client->clkid);
>
> static ktime_t get_clk_time(int id)
> {
> switch (id) {
>
> case CLOCK_REALTIME: return ktime_get_real();
> case CLOCK_MONOTONIC: return ktime_get();
> case CLOCK_BOOTTIME: return ktime_get_bootime();
> }
> }
Just open-code it in evdev_queue_syn_dropped() since there is only place
where we call it. And use clk_type instead of clock id-.
>
> >> ev.time = ktime_to_timeval(time);
> >> ev.type = EV_SYN;
> >> @@ -159,7 +167,7 @@ static void __pass_event(struct evdev_client *client,
> >>
> >> static void evdev_pass_values(struct evdev_client *client,
> >> const struct input_value *vals, unsigned int count,
> >> - ktime_t mono, ktime_t real)
> >> + ktime_t *ev_time)
> >> {
> >> struct evdev *evdev = client->evdev;
> >> const struct input_value *v;
> >> @@ -169,8 +177,9 @@ static void evdev_pass_values(struct evdev_client *client,
> >> if (client->revoked)
> >> return;
> >>
> >> - event.time = ktime_to_timeval(client->clkid == CLOCK_MONOTONIC ?
> >> - mono : real);
> >> + event.time = ktime_to_timeval(client->clkid == CLOCK_REALTIME ?
> >> + ev_time[REAL] : client->clkid == CLOCK_MONOTONIC ?
> >> + ev_time[MONO] : ev_time[BOOT]);
> >
> > This becomes unwieldy. Should we have client->clk_type instead of
> > client->clkid and convert CLOCK_* into your EVDEV_CLK_{REAL|MONO|BOOT}
> > when setting it in ioctl and then do
> >
> > event.time = ktime_to_timeval(ev_time[client->clk_offset]);
> >
>
> Sure, using clk_type would be better and improve code readability.
>
> I am afraid how converting CLOCK_* into your
> EVDEV_CLK_{REAL|MONO|BOOT} will help
> because we cannot have ev_time array size more than CLK_MAX (3).
>
> Did you mean to have following changes:
>
> 1. Add clk_type variable
> struct evdev_client {
> int clkid:
> + int clk_type;
> }
I meant replacing clkid with clk_type in evdev_client.
>
> 2. Add new funtion for setting clk_type to improve readability
> static int set_clk_type(struct evdev_client *client, int id)
evdev_set_clk_type() to keep with the style.
> {
> switch (id) {
>
> case CLOCK_REALTIME: client->clk_type = EV_REAL; break;
> case CLOCK_MONOTONIC: client->clk_type = EV_MONO; break;
> case CLOCK_BOOTTIME: client->clk_type = EV_BOOT; break;
> default: return -1
-EINVAL here, otherwise yes.
> }
>
> return 0;
> }
>
> 3. Addition in ioctl call
> case EVIOCSCLOCKID:
> ...
> if (!set_clk_type())
> return -EINVAL;
>
error = evdev_set_clktype(i);
if (error)
return error;
> client->clkid = i;
Drop this.
> return 0;
>
> 4. Change in evdev_pass_values function
> event.time = ktime_to_timeval(ev_time[client->clk_type]);
Yes.
>
> >>
> >> /* Interrupts are disabled, just acquire the lock. */
> >> spin_lock(&client->buffer_lock);
> >> @@ -198,21 +207,21 @@ static void evdev_events(struct input_handle *handle,
> >> {
> >> struct evdev *evdev = handle->private;
> >> struct evdev_client *client;
> >> - ktime_t time_mono, time_real;
> >> + ktime_t ev_time[CLK_MAX];
> >>
> >> - time_mono = ktime_get();
> >> - time_real = ktime_mono_to_real(time_mono);
> >> + ev_time[MONO] = ktime_get();
> >> + ev_time[REAL] = ktime_mono_to_real(ev_time[MONO]);
> >> + ev_time[BOOT] = ktime_get_boottime();
> >
> > I do not think we want to use ktime_get_boottime() here; I'd rather you
> > use ktime_mono_to_anY(ev_time[MONO], TK_OFFS_BOOT) so that all 3 times
> > are consistent.
> >
>
> Sure. I will send the updated patch with this change.
>
> >>
> >> rcu_read_lock();
> >>
> >> client = rcu_dereference(evdev->grab);
> >>
> >> if (client)
> >> - evdev_pass_values(client, vals, count, time_mono, time_real);
> >> + evdev_pass_values(client, vals, count, ev_time);
> >> else
> >> list_for_each_entry_rcu(client, &evdev->client_list, node)
> >> - evdev_pass_values(client, vals, count,
> >> - time_mono, time_real);
> >> + evdev_pass_values(client, vals, count, ev_time);
> >>
> >> rcu_read_unlock();
> >> }
> >> @@ -874,7 +883,7 @@ static long evdev_do_ioctl(struct file *file, unsigned int cmd,
> >> case EVIOCSCLOCKID:
> >> if (copy_from_user(&i, p, sizeof(unsigned int)))
> >> return -EFAULT;
> >> - if (i != CLOCK_MONOTONIC && i != CLOCK_REALTIME)
> >> + if (i != CLOCK_MONOTONIC && i != CLOCK_REALTIME && i != CLOCK_BOOTTIME)
> >> return -EINVAL;
> >> client->clkid = i;
> >> return 0;
> >> --
> >> 1.9.1
> >>
> >
> > Thanks.
> >
> > --
> > Dmitry
>
> Thanks,
> Aniroop Mathur
--
Dmitry
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