On Wed, May 06, 2015 at 01:46:36AM +0200, Marek Vasut wrote: > Use msecs_to_jiffies(50) instead of plain (HZ / 50) as the > former is independent of kernel HZ settings and provides > stable delay. > > The delay here must be stable, otherwise we might start polling > for pen-up event too early. This would in turn render the > touchscreen unusable. Doesn't jiffy "size" depend on HZ value? I'd expect the delay be "stable" regardless of the value of HZ. I do not disagree with the patch, but I think you need better justification here (except I think the delay should be 20 msec, not 50, and we may use a constant instead of reevaluating it all the time). > > Signed-off-by: Marek Vasut <marex@xxxxxxx> > Cc: Vipul Kumar Samar <vipulkumar.samar@xxxxxx> > Cc: Viresh Kumar <viresh.kumar@xxxxxxxxxx> > Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> > --- > drivers/input/touchscreen/stmpe-ts.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > NOTE: This applies all the way back to Linux ~2.6.36, so I should > probably also submit this for -stable if acceptable ? No, I do not think it needs to be in stable as it does not really fix any bug as far as I can see. > > diff --git a/drivers/input/touchscreen/stmpe-ts.c b/drivers/input/touchscreen/stmpe-ts.c > index 42ce31a..a8f5ea7 100644 > --- a/drivers/input/touchscreen/stmpe-ts.c > +++ b/drivers/input/touchscreen/stmpe-ts.c > @@ -164,7 +164,7 @@ static irqreturn_t stmpe_ts_handler(int irq, void *data) > STMPE_TSC_CTRL_TSC_EN, STMPE_TSC_CTRL_TSC_EN); > > /* start polling for touch_det to detect release */ > - schedule_delayed_work(&ts->work, HZ / 50); > + schedule_delayed_work(&ts->work, msecs_to_jiffies(50)); > > return IRQ_HANDLED; > } > -- > 2.1.4 > Thanks. -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
