From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932096Ab1KHD5v (ORCPT ); Mon, 7 Nov 2011 22:57:51 -0500 Received: from mailservice.tudelft.nl ([130.161.131.5]:33641 "EHLO mailservice.tudelft.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753437Ab1KHD5u (ORCPT ); Mon, 7 Nov 2011 22:57:50 -0500 X-Spam-Flag: NO X-Spam-Score: -9.468 Message-ID: <4EB8A8B6.1010205@tremplin-utc.net> Date: Tue, 08 Nov 2011 04:57:42 +0100 From: =?ISO-8859-1?Q?=C9ric_Piel?= User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:7.0.1) Gecko/20111006 Thunderbird/7.0.1 MIME-Version: 1.0 To: Takashi Iwai CC: Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH] lis3lv02d: Avoid zero-division References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Op 03-11-11 13:09, Takashi Iwai schreef: > In some weird situation, HP DriveGuard chip can't read ODR value > correctly, and it results in a zero-division Oops in lis3lv02d driver. > This patch fixes the Oops by checking the value appopriately, and skips > if any weird value is read. Hi Takashi, Actually, a similar patch already just landed in linus' tree: 1510dd5954 (lis3lv02d: avoid divide by zero due to unchecked) However, in the patch applied, the device is disabled (until next reboot) while in yours, the sleep is just skipped. Does it work again after the read of odr fails? If so, maybe I could improve the current version by, after the odr read fails, sleeping a long and safe time and then trying to read the odr again. Then if it fails again, we give up, otherwise the device can be used again. Do you have such a device yourself? Could you let me know if after a failing read of the odr, the device keeps working? Cheers, Éric > > Cc: > Signed-off-by: Takashi Iwai > --- > drivers/misc/lis3lv02d/lis3lv02d.c | 14 +++++++++++--- > 1 files changed, 11 insertions(+), 3 deletions(-) > > diff --git a/drivers/misc/lis3lv02d/lis3lv02d.c b/drivers/misc/lis3lv02d/lis3lv02d.c > index 8b51cd6..c4eb2f3 100644 > --- a/drivers/misc/lis3lv02d/lis3lv02d.c > +++ b/drivers/misc/lis3lv02d/lis3lv02d.c > @@ -228,6 +228,14 @@ static int lis3lv02d_set_odr(int rate) > return -EINVAL; > } > > +static void lis3lv02d_power_delay(struct lis3lv02d *lis3) > +{ > + int odr = lis3lv02d_get_odr(); > + if (odr<= 0) > + return; > + msleep(lis3->pwron_delay / odr); > +} > + > static int lis3lv02d_selftest(struct lis3lv02d *lis3, s16 results[3]) > { > u8 ctlreg, reg; > @@ -266,7 +274,7 @@ static int lis3lv02d_selftest(struct lis3lv02d *lis3, s16 results[3]) > > lis3->read(lis3, ctlreg,®); > lis3->write(lis3, ctlreg, (reg | selftest)); > - msleep(lis3->pwron_delay / lis3lv02d_get_odr()); > + lis3lv02d_power_delay(lis3); > > /* Read directly to avoid axis remap */ > x = lis3->read_data(lis3, OUTX); > @@ -275,7 +283,7 @@ static int lis3lv02d_selftest(struct lis3lv02d *lis3, s16 results[3]) > > /* back to normal settings */ > lis3->write(lis3, ctlreg, reg); > - msleep(lis3->pwron_delay / lis3lv02d_get_odr()); > + lis3lv02d_power_delay(lis3); > > results[0] = x - lis3->read_data(lis3, OUTX); > results[1] = y - lis3->read_data(lis3, OUTY); > @@ -385,7 +393,7 @@ void lis3lv02d_poweron(struct lis3lv02d *lis3) > } > > /* LIS3 power on delay is quite long */ > - msleep(lis3->pwron_delay / lis3lv02d_get_odr()); > + lis3lv02d_power_delay(lis3); > > if (lis3->reg_ctrl) > lis3_context_restore(lis3);