From patchwork Fri Jun 25 06:59:22 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oleksij Rempel X-Patchwork-Id: 12343715 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 83EFCC49EB7 for ; Fri, 25 Jun 2021 06:59:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6D701613F3 for ; Fri, 25 Jun 2021 06:59:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230004AbhFYHBz (ORCPT ); Fri, 25 Jun 2021 03:01:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40070 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229974AbhFYHBy (ORCPT ); Fri, 25 Jun 2021 03:01:54 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF9F8C061756 for ; Thu, 24 Jun 2021 23:59:33 -0700 (PDT) Received: from dude.hi.pengutronix.de ([2001:67c:670:100:1d::7]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lwfoD-0007c2-8u; Fri, 25 Jun 2021 08:59:25 +0200 Received: from ore by dude.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1lwfoC-0002BY-16; Fri, 25 Jun 2021 08:59:24 +0200 From: Oleksij Rempel To: Rob Herring , Jonathan Cameron Cc: Oleksij Rempel , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Pengutronix Kernel Team , David Jander , Robin van der Gracht , linux-iio@vger.kernel.org, Lars-Peter Clausen , Peter Meerwald-Stadler , Dmitry Torokhov Subject: [PATCH v1 2/2] iio: adc: tsc2046: fix sleeping in atomic context warning and a deadlock after iio_trigger_poll() call Date: Fri, 25 Jun 2021 08:59:22 +0200 Message-Id: <20210625065922.8310-2-o.rempel@pengutronix.de> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210625065922.8310-1-o.rempel@pengutronix.de> References: <20210625065922.8310-1-o.rempel@pengutronix.de> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::7 X-SA-Exim-Mail-From: ore@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-iio@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org If iio_trigger_poll() is called after IRQ was disabled, we will call reenable_trigger() directly from hard IRQ or hrtimer context instead of IRQ thread. In this case we will run in to multiple issue as sleeping in atomic context and a deadlock. To avoid this issue, rework the trigger to use state machine. All state changes are done over the hrtimer, so it allows us to drop fsleep() and avoid the deadlock. Fixes: 9374e8f5a38d ("iio: adc: add ADC driver for the TI TSC2046 controller") Signed-off-by: Oleksij Rempel --- drivers/iio/adc/ti-tsc2046.c | 102 ++++++++++++++++++++--------------- 1 file changed, 58 insertions(+), 44 deletions(-) diff --git a/drivers/iio/adc/ti-tsc2046.c b/drivers/iio/adc/ti-tsc2046.c index d84ae6b008c1..91f6bd5effe7 100644 --- a/drivers/iio/adc/ti-tsc2046.c +++ b/drivers/iio/adc/ti-tsc2046.c @@ -123,14 +123,21 @@ struct tsc2046_adc_ch_cfg { unsigned int oversampling_ratio; }; +enum tsc2046_state { + TSC2046_STATE_STANDBY, + TSC2046_STATE_ENABLE_IRQ_POLL, + TSC2046_STATE_POLL, + TSC2046_STATE_ENABLE_IRQ, +}; + struct tsc2046_adc_priv { struct spi_device *spi; const struct tsc2046_adc_dcfg *dcfg; struct iio_trigger *trig; struct hrtimer trig_timer; - spinlock_t trig_lock; - unsigned int trig_more_count; + enum tsc2046_state state; + spinlock_t state_lock; struct spi_transfer xfer; struct spi_message msg; @@ -411,21 +418,47 @@ static const struct iio_info tsc2046_adc_info = { .update_scan_mode = tsc2046_adc_update_scan_mode, }; -static enum hrtimer_restart tsc2046_adc_trig_more(struct hrtimer *hrtimer) +static enum hrtimer_restart tsc2046_adc_timer(struct hrtimer *hrtimer) { struct tsc2046_adc_priv *priv = container_of(hrtimer, struct tsc2046_adc_priv, trig_timer); unsigned long flags; - spin_lock_irqsave(&priv->trig_lock, flags); - - disable_irq_nosync(priv->spi->irq); - - priv->trig_more_count++; - iio_trigger_poll(priv->trig); - - spin_unlock_irqrestore(&priv->trig_lock, flags); + spin_lock_irqsave(&priv->state_lock, flags); + switch (priv->state) { + case TSC2046_STATE_ENABLE_IRQ_POLL: + /* + * IRQ handler called iio_trigger_poll() to sample ADC. + * Here we + * - re-enable IRQs + * - start hrtimer for timeout if no IRQ will occur + */ + priv->state = TSC2046_STATE_POLL; + enable_irq(priv->spi->irq); + hrtimer_start(&priv->trig_timer, + ns_to_ktime(priv->scan_interval_us * + NSEC_PER_USEC), + HRTIMER_MODE_REL_SOFT); + break; + case TSC2046_STATE_POLL: + disable_irq_nosync(priv->spi->irq); + priv->state = TSC2046_STATE_ENABLE_IRQ; + /* iio_trigger_poll() starts hrtimer */ + iio_trigger_poll(priv->trig); + break; + case TSC2046_STATE_ENABLE_IRQ: + priv->state = TSC2046_STATE_STANDBY; + enable_irq(priv->spi->irq); + break; + case TSC2046_STATE_STANDBY: + fallthrough; + default: + dev_warn(&priv->spi->dev, "Got unexpected state: %i\n", + priv->state); + break; + } + spin_unlock_irqrestore(&priv->state_lock, flags); return HRTIMER_NORESTART; } @@ -434,16 +467,17 @@ static irqreturn_t tsc2046_adc_irq(int irq, void *dev_id) { struct iio_dev *indio_dev = dev_id; struct tsc2046_adc_priv *priv = iio_priv(indio_dev); - - spin_lock(&priv->trig_lock); + unsigned long flags; hrtimer_try_to_cancel(&priv->trig_timer); - priv->trig_more_count = 0; + spin_lock_irqsave(&priv->state_lock, flags); disable_irq_nosync(priv->spi->irq); - iio_trigger_poll(priv->trig); + priv->state = TSC2046_STATE_ENABLE_IRQ_POLL; - spin_unlock(&priv->trig_lock); + /* iio_trigger_poll() starts hrtimer */ + iio_trigger_poll(priv->trig); + spin_unlock_irqrestore(&priv->state_lock, flags); return IRQ_HANDLED; } @@ -452,37 +486,16 @@ static void tsc2046_adc_reenable_trigger(struct iio_trigger *trig) { struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig); struct tsc2046_adc_priv *priv = iio_priv(indio_dev); - unsigned long flags; - int delta; + ktime_t tim; /* * We can sample it as fast as we can, but usually we do not need so * many samples. Reduce the sample rate for default (touchscreen) use * case. - * Currently we do not need a highly precise sample rate. It is enough - * to have calculated numbers. - */ - delta = priv->scan_interval_us - priv->time_per_scan_us; - if (delta > 0) - fsleep(delta); - - spin_lock_irqsave(&priv->trig_lock, flags); - - /* - * We need to trigger at least one extra sample to detect state - * difference on ADC side. */ - if (!priv->trig_more_count) { - int timeout_ms = DIV_ROUND_UP(priv->scan_interval_us, - USEC_PER_MSEC); - - hrtimer_start(&priv->trig_timer, ms_to_ktime(timeout_ms), - HRTIMER_MODE_REL_SOFT); - } - - enable_irq(priv->spi->irq); - - spin_unlock_irqrestore(&priv->trig_lock, flags); + tim = ns_to_ktime((priv->scan_interval_us - priv->time_per_scan_us) * + NSEC_PER_USEC); + hrtimer_start(&priv->trig_timer, tim, HRTIMER_MODE_REL_SOFT); } static int tsc2046_adc_set_trigger_state(struct iio_trigger *trig, bool enable) @@ -493,8 +506,8 @@ static int tsc2046_adc_set_trigger_state(struct iio_trigger *trig, bool enable) if (enable) { enable_irq(priv->spi->irq); } else { + hrtimer_cancel(&priv->trig_timer); disable_irq(priv->spi->irq); - hrtimer_try_to_cancel(&priv->trig_timer); } return 0; @@ -668,10 +681,11 @@ static int tsc2046_adc_probe(struct spi_device *spi) iio_trigger_set_drvdata(trig, indio_dev); trig->ops = &tsc2046_adc_trigger_ops; - spin_lock_init(&priv->trig_lock); + spin_lock_init(&priv->state_lock); + priv->state = TSC2046_STATE_STANDBY; hrtimer_init(&priv->trig_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT); - priv->trig_timer.function = tsc2046_adc_trig_more; + priv->trig_timer.function = tsc2046_adc_timer; ret = devm_iio_trigger_register(dev, trig); if (ret) {