From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:57324 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751420AbdHMMMx (ORCPT ); Sun, 13 Aug 2017 08:12:53 -0400 Date: Sun, 13 Aug 2017 13:12:46 +0100 From: Jonathan Cameron To: Srinivas Pandruvada Cc: hadess@hadess.net, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] iio: hid-sensor-trigger: Fix the race with user space powering up sensors Message-ID: <20170813131246.5d97a020@archlinux> In-Reply-To: <1502554161-9300-1-git-send-email-srinivas.pandruvada@linux.intel.com> References: <1502554161-9300-1-git-send-email-srinivas.pandruvada@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org On Sat, 12 Aug 2017 09:09:21 -0700 Srinivas Pandruvada wrote: > It has been reported for a while that with iio-sensor-proxy service the > rotation only works after one suspend/resume cycle. This required a wait > in the systemd unit file to avoid race. I found a Yoga 900 where I could > reproduce this. > > The problem scenerio is: > - During sensor driver init, enable run time PM and also set a > auto-suspend for 3 seconds. > This result in one runtime resume. But there is a check to avoid > a powerup in this sequence, but rpm is active > - User space iio-sensor-proxy tries to power up the sensor. Since rpm is > active it will simply return. But sensors were not actually > powered up in the prior sequence, so actaully the sensors will not work > - After 3 seconds the auto suspend kicks > > If we add a wait in systemd service file to fire iio-sensor-proxy after > 3 seconds, then now everything will work as the runtime resume will > actually powerup the sensor as this is a user request. > > To avoid this: > - Remove the check to match user requested state, this will cause a > brief powerup, but if the iio-sensor-proxy starts immediately it will > still work as the sensors are ON. > - Also move the autosuspend delay to place when user requested turn off > of sensors, like after user finished raw read or buffer disable > > Signed-off-by: Srinivas Pandruvada > Tested-by: Bastien Nocera > Applied to the fixes-togreg branch of iio.git and marked for stable. Thanks, Jonathan > --- > Changes: > Removed RFT and added Tested-by tag. > > drivers/iio/common/hid-sensors/hid-sensor-trigger.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/iio/common/hid-sensors/hid-sensor-trigger.c b/drivers/iio/common/hid-sensors/hid-sensor-trigger.c > index 16ade0a..0e4b379 100644 > --- a/drivers/iio/common/hid-sensors/hid-sensor-trigger.c > +++ b/drivers/iio/common/hid-sensors/hid-sensor-trigger.c > @@ -111,8 +111,6 @@ static int _hid_sensor_power_state(struct hid_sensor_common *st, bool state) > s32 poll_value = 0; > > if (state) { > - if (!atomic_read(&st->user_requested_state)) > - return 0; > if (sensor_hub_device_open(st->hsdev)) > return -EIO; > > @@ -161,6 +159,9 @@ static int _hid_sensor_power_state(struct hid_sensor_common *st, bool state) > &report_val); > } > > + pr_debug("HID_SENSOR %s set power_state %d report_state %d\n", > + st->pdev->name, state_val, report_val); > + > sensor_hub_get_feature(st->hsdev, st->power_state.report_id, > st->power_state.index, > sizeof(state_val), &state_val); > @@ -182,6 +183,7 @@ int hid_sensor_power_state(struct hid_sensor_common *st, bool state) > ret = pm_runtime_get_sync(&st->pdev->dev); > else { > pm_runtime_mark_last_busy(&st->pdev->dev); > + pm_runtime_use_autosuspend(&st->pdev->dev); > ret = pm_runtime_put_autosuspend(&st->pdev->dev); > } > if (ret < 0) { > @@ -285,8 +287,6 @@ int hid_sensor_setup_trigger(struct iio_dev *indio_dev, const char *name, > /* Default to 3 seconds, but can be changed from sysfs */ > pm_runtime_set_autosuspend_delay(&attrb->pdev->dev, > 3000); > - pm_runtime_use_autosuspend(&attrb->pdev->dev); > - > return ret; > error_unreg_trigger: > iio_trigger_unregister(trig);