media: pwm-ir-tx: Correct timer calculation

[6by9]

Commit 44d7fb8 ("media: pwm-ir-tx: Avoid direct access to hrtimer clockbase") converted a loop conditional from
now = timer->base->get_time();
} while (hrtimer_get_expires_tv64(timer) < now);
to
while (hrtimer_expires_remaining(timer) > 0);

hrtimer_expires_remaining returns (expires - now), so the change has inverted the condition.

Correct the > to < to restore the old behaviour

#7678

Fixes: 44d7fb8 ("media: pwm-ir-tx: Avoid direct access to hrtimer clockbase")

[6by9]

Draft PR for reporter to test.

[popcornmix]

@t-8ch - I think this wants fixing upstream.

[t-8ch]

@t-8ch - I think this wants fixing upstream.

Yes, agreed.

@6by9 Can you submit this upstream?
Also add Cc: stable@vger.kernel.org.

Maybe it should change to this:

} while (hrtimer_get_expires(timer) < hrtimer_cb_get_time(timer));

This is closer to the original logic and IMO easier to understand.
Case in point: I got confused by my own change here...

[6by9]

Yup, happy to submit it upstream, making your suggested change first.

I'll update this PR too so hopefully we'll avoid merge conflicts when it does merge back through stable.

[6by9]

PR updated based on suggested option.
I've asked on #7678 for them to retest, and I'll send upstream once confirmed.

[6by9]

Tested by the original reporter and confirmed working

Sent upstream - https://lore.kernel.org/linux-media/20261014-media-rc-pwm-ir-tx-v1-1-1ae862427fd2@raspberrypi.com/T/#u

Merging here.