From mboxrd@z Thu Jan 1 00:00:00 1970 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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED autolearn=ham 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 91CD5C282D7 for ; Sat, 2 Feb 2019 10:20:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 59C75217D6 for ; Sat, 2 Feb 2019 10:20:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549102857; bh=+fdH/w2zAugmHdwEMMQcXoW9UFPDCuiV2igdmI2iw1I=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=l6Z6kLrl+aQvGtbr35i2xG8UB1iN5Zly9xKOlUTJl5OoN6a2YqYukVQLY4UVhGq74 XkwFQMwpIf4ke+ZhzONJbT+5+3LvhwVZVV0LlJNa7sPntuxdF7CxgomLuY3YvxNAH5 CbsF2/Tp8PYqhbAQE5W8qQER0dyaGF107XiRjRxY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726571AbfBBKU4 (ORCPT ); Sat, 2 Feb 2019 05:20:56 -0500 Received: from mail.kernel.org ([198.145.29.99]:45016 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726540AbfBBKU4 (ORCPT ); Sat, 2 Feb 2019 05:20:56 -0500 Received: from archlinux (cpc91196-cmbg18-2-0-cust659.5-4.cable.virginm.net [81.96.234.148]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B247020870; Sat, 2 Feb 2019 10:20:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549102855; bh=+fdH/w2zAugmHdwEMMQcXoW9UFPDCuiV2igdmI2iw1I=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=i2bZLGxzujncRYN/k8bXege1x2mJt3q3jmNUPvLeKJc6HDt+ixFcXRK1iouTUsjZE H4JcxMZMFuSjj/da+1GyIWu8+6qtY7QkABU+rToJefd5jmUkKvpm6IUMQduWFeJXkN co9qcgROXoXKQljTiJtyNSKa2zSTzJ7SzRjw+ISM= Date: Sat, 2 Feb 2019 10:20:48 +0000 From: Jonathan Cameron To: Cc: , , Hartmut Knaack , Lars-Peter Clausen , Peter Meerwald-Stadler , Nicolas Ferre , Alexandre Belloni , Ludovic Desroches , "David S. Miller" , Ard Biesheuvel , Kees Cook , , , , Maxime Ripard Subject: Re: [PATCH] iio: adc: at91: disable adc channel interrupt in timeout case Message-ID: <20190202102021.12bb0a72@archlinux> In-Reply-To: <20190130134202.5831-1-g.ottinger@abatec.at> References: <20190130134202.5831-1-g.ottinger@abatec.at> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org On Wed, 30 Jan 2019 14:42:02 +0100 wrote: > From: Georg Ottinger > > Having a brief look at at91_adc_read_raw() it is obvious that in the case > of a timeout the setting of AT91_ADC_CHDR and AT91_ADC_IDR registers is > omitted. If 2 different channels are queried we can end up with a > situation where two interrupts are enabled, but only one interrupt is > cleared in the interrupt handler. Resulting in a interrupt loop and a > system hang. > > Signed-off-by: Georg Ottinger Whilst I agree this looks like a correct change, I would like Maxime to take a look as he is obviously much more familiar with the driver than I am. I suspect you can only actually get there in the event of a hardware failure as that isn't actually a timeout you should ever see. Could be wrong though! Thanks, Jonathan > --- > drivers/iio/adc/at91_adc.c | 28 +++++++++++++++++----------- > 1 file changed, 17 insertions(+), 11 deletions(-) > > diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c > index 75d2f7358..596841a3c 100644 > --- a/drivers/iio/adc/at91_adc.c > +++ b/drivers/iio/adc/at91_adc.c > @@ -704,23 +704,29 @@ static int at91_adc_read_raw(struct iio_dev *idev, > ret = wait_event_interruptible_timeout(st->wq_data_avail, > st->done, > msecs_to_jiffies(1000)); > - if (ret == 0) > - ret = -ETIMEDOUT; > - if (ret < 0) { > - mutex_unlock(&st->lock); > - return ret; > - } > - > - *val = st->last_value; > > + /* Disable interrupts, regardless if adc conversion was > + * successful or not > + */ > at91_adc_writel(st, AT91_ADC_CHDR, > AT91_ADC_CH(chan->channel)); > at91_adc_writel(st, AT91_ADC_IDR, BIT(chan->channel)); > > - st->last_value = 0; > - st->done = false; > + if (ret > 0) { > + /* a valid conversion took place */ > + *val = st->last_value; > + st->last_value = 0; > + st->done = false; > + ret = IIO_VAL_INT; > + } else if (ret == 0) { > + /* conversion timeout */ > + dev_err(&idev->dev, "ADC Channel %d timeout.\n", > + chan->channel); > + ret = -ETIMEDOUT; > + } > + > mutex_unlock(&st->lock); > - return IIO_VAL_INT; > + return ret; > > case IIO_CHAN_INFO_SCALE: > *val = st->vref_mv;