Re: [PATCH] media: rc: Replace timeval with ktime_t in imon.c

Mauro Carvalho Chehab
2014-12-18T11:01:04Z

Em Thu, 18 Dec 2014 17:38:14 +0800
Chunyan Zhang <zhang.chunyan@linaro.org> escreveu:

> On Thu, Dec 18, 2014 at 3:50 PM, Arnd Bergmann <arnd@linaro.org> wrote:
> > On Thursday 18 December 2014 11:37:13 Chunyan Zhang wrote:
> >> This patch changes the 32-bit time type (timeval) to the 64-bit one
> >> (ktime_t), since 32-bit time types will break in the year 2038.
> >>
> >> I use ktime_t instead of all uses of timeval in imon.c
> >>
> >> This patch also changes do_gettimeofday() to ktime_get() accordingly,
> >> since ktime_get returns a ktime_t, but do_gettimeofday returns a
> >> struct timeval, and the other reason is that ktime_get() uses
> >> the monotonic clock.
> >>
> >> This patch use a new function which is provided by another patch listed below
> >> to get the millisecond time difference.
> >
> > The patch looks great. Just a few small details that could still be
> > improved:

Yes, patch looks OK. After addressing the bits pointed by Arnd:

Acked-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

Feel free to merge via y2038 tree.

> >
> >> http://lkml.iu.edu//hypermail/linux/kernel/1412.2/00625.html
> >>
> >> Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
> >
> > In general, when you give a mailing list link, use the 'Link' tag
> > under your Signed-off-by line, like
> >
> > Link: http://lkml.iu.edu//hypermail/linux/kernel/1412.2/00625.html
> >
> > It's not used much yet, but getting more popular and seems useful to me.
> >
> > In this particular case, when you have patches that depend on one
> > another, you can make do it even better by sending all three patches
> > as a series with a [PATCH 0/3] cover letter.
> >
> OK, I'll send a patch-set including these three patches
>
> > If the media maintainers can provide an Ack for this patch, I would
> > suggest to queue it up in the y2038 branch together with your first
> > patch that it depends on.
> >
> >> @@ -1191,16 +1168,16 @@ static inline int tv2int(const struct timeval *a, const struct timeval *b)
> >> */
> >> static int stabilize(int a, int b, u16 timeout, u16 threshold)
> >> {
> >> - struct timeval ct;
> >> - static struct timeval prev_time = {0, 0};
> >> - static struct timeval hit_time = {0, 0};
> >> + ktime_t ct;
> >> + static ktime_t prev_time = {0};
> >> + static ktime_t hit_time = {0};
> >> static int x, y, prev_result, hits;
> >> int result = 0;
> >
> > The "= {0}" part here is redundant, since static variables are always
> > initialized to zero. Normally, adding the explicit initializer can
> > help readability, but in this case I would leave it out because it shows
> > implementation details of ktime_t that are better hidden from drivers.
> >
> OK, I'll modify them soon
>
> Thanks,
> Chunyan
>
> >> @@ -1596,9 +1573,9 @@ static void imon_incoming_packet(struct imon_context *ictx,
> >> int i;
> >> u64 scancode;
> >> int press_type = 0;
> >> - int msec;
> >> - struct timeval t;
> >> - static struct timeval prev_time = { 0, 0 };
> >> + long msec;
> >> + ktime_t t;
> >> + static ktime_t prev_time = {0};
> >> u8 ktype;
> >
> > Same thing here of course.
> >
> > Arnd