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();
}
}
>> 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;
}
2. Add new funtion for setting clk_type to improve readability
static int set_clk_type(struct evdev_client *client, int id)
{
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
}
return 0;
}
3. Addition in ioctl call
case EVIOCSCLOCKID:
...
if (!set_clk_type())
return -EINVAL;
client->clkid = i;
return 0;
4. Change in evdev_pass_values function
event.time = ktime_to_timeval(ev_time[client->clk_type]);
>>
>> /* 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
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