From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: [PATCH] Input: smtpe-ts: Use msecs_to_jiffies() instead of HZ Date: Tue, 5 May 2015 17:01:35 -0700 Message-ID: <20150506000135.GA25707@dtor-ws> References: <1430869596-7044-1-git-send-email-marex@denx.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-ig0-f179.google.com ([209.85.213.179]:35642 "EHLO mail-ig0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751506AbbEFABj (ORCPT ); Tue, 5 May 2015 20:01:39 -0400 Received: by igbyr2 with SMTP id yr2so117540050igb.0 for ; Tue, 05 May 2015 17:01:39 -0700 (PDT) Content-Disposition: inline In-Reply-To: <1430869596-7044-1-git-send-email-marex@denx.de> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Marek Vasut Cc: linux-input@vger.kernel.org, Vipul Kumar Samar , Viresh Kumar 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 > Cc: Vipul Kumar Samar > Cc: Viresh Kumar > Cc: Dmitry Torokhov > --- > 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