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=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 79F2CC282C4 for ; Mon, 4 Feb 2019 07:17:21 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 404B3217D9 for ; Mon, 4 Feb 2019 07:17:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="GPkkGiay" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 404B3217D9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=abatec.at Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:In-Reply-To:References: Message-ID:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=72uWws98UZvavJ/RJxU3JaxB7xuwkZ4tGtPpqCELRsU=; b=GPkkGiayEZ3/Ui WvzwcZNc/9vFspZm2GPlv2CrW76EzHZ4rjC1AhUfoS+3mwrfggcGFq4gIB4+pz1F3/j25fyiUdwDf o1cf/qaZHRTy+qGbTjHMXt2gWZk8ge8JMCIAt7M2fD5I8YMnIfjTiuf4lTSbTSu7URSu7aDZpKk/0 +BboLRr8qoMZz91VKK0K0EIpSMvzxyX1ygx8TvmqD4aRVTA7DlyPMc0UMEM2IEaLi9nwFqLdh6TL1 Eja1eVKnc11BM+EOR9WqP2qGGOQV3v2vdimGgGOii0PfjeNgeCOFDv0Z++Nfb0w1SAG9Fvh32hUaw pmGNfzKU9BFN05ynP+pg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gqYVI-0007jl-Aj; Mon, 04 Feb 2019 07:17:16 +0000 Received: from mail1.abatec.at ([81.10.186.19]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gqYVD-0007gx-EH for linux-arm-kernel@lists.infradead.org; Mon, 04 Feb 2019 07:17:14 +0000 Received: from exchange02.regau.abatec.at (192.168.100.22) by exchange02.regau.abatec.at (192.168.100.22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1415.2; Mon, 4 Feb 2019 08:17:07 +0100 Received: from exchange02.regau.abatec.at ([::1]) by exchange02.regau.abatec.at ([::1]) with mapi id 15.01.1415.002; Mon, 4 Feb 2019 08:17:07 +0100 From: Georg Ottinger To: Jonathan Cameron Subject: AW: [PATCH] iio: adc: at91: disable adc channel interrupt in timeout case Thread-Topic: [PATCH] iio: adc: at91: disable adc channel interrupt in timeout case Thread-Index: AQHUuKGafWrpkxg4ckeOny6mkh/hBaXMP+cAgAMB7lA= Date: Mon, 4 Feb 2019 07:17:07 +0000 Message-ID: <0974ce54b3da4d82b6bd3026a3de5ff3@abatec.at> References: <20190130134202.5831-1-g.ottinger@abatec.at> <20190202102021.12bb0a72@archlinux> In-Reply-To: <20190202102021.12bb0a72@archlinux> Accept-Language: de-AT, en-US Content-Language: de-DE X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [192.168.115.56] MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190203_231711_662595_EB72C8AC X-CRM114-Status: GOOD ( 19.47 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Alexandre Belloni , Lars-Peter Clausen , Kees Cook , Ard Biesheuvel , "linux-iio@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Maxime Ripard , Ludovic Desroches , Peter Meerwald-Stadler , Hartmut Knaack , "eugen.hristev@microchip.com" , Stefan Etzlstorfer , "David S. Miller" , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Actually this issue occurred to us with an concrete product, where we exper= ienced a system hang at -20 =B0C. It was triggered by a race condition between the Touch Trigger and the Chan= nel Trigger of the ADC. Once triggered we got in to the situation where an = ongoing Channel Conversion was lost (Timeout case).When we queried a second= channel than we got a system hang. Investigating this issue we developed a= n error demonstrator - reading alternating two channels as fast as possible= (when Touch is enabled). This also provokes this issue at room temperature. For the error demonstrator use following commandline to compile: $ arm-buildroot-linux-gnueabihf-gcc adc_demo_error.c -D2ND_CHANNEL -o adc_d= emo_error2 ------------- // adc_demo_error.c #include #include #define VLEN 10 int main() { int fd_adc,fd_adc2; int ret; char dummy[VLEN]; = fd_adc =3D open ("/sys/devices/platform/ahb/ahb:apb/f8018000.adc/iio:devi= ce0/in_voltage4_raw",O_RDONLY); = #ifdef 2ND_CHANNEL fd_adc2 =3D open ("/sys/devices/platform/ahb/ahb:apb/f8018000.adc/iio:dev= ice0/in_voltage5_raw",O_RDONLY); #endif while(1) { lseek(fd_adc, 0, SEEK_SET); ret =3D read(fd_adc, dummy, VLEN); #ifdef 2ND_CHANNEL lseek(fd_adc2, 0, SEEK_SET); ret =3D read(fd_adc2, dummy, VLEN); #endif } } ------------ Greeting, Georg -----Urspr=FCngliche Nachricht----- Von: Jonathan Cameron [mailto:jic23@kernel.org] = Gesendet: Samstag, 02. Februar 2019 11:21 An: Georg Ottinger Cc: eugen.hristev@microchip.com; Stefan Etzlstorfer ; Hartmut Knaack ; Lars-Peter Clausen ;= Peter Meerwald-Stadler ; Nicolas Ferre ; Alexandre Belloni ; Ludovic D= esroches ; David S. Miller ; Ard Biesheuvel ; Kees Cook ; linux-iio@vger.kernel.org; linux-arm-kernel@lists.infradead.org= ; linux-kernel@vger.kernel.org; Maxime Ripard Betreff: Re: [PATCH] iio: adc: at91: disable adc channel interrupt in timeo= ut case 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 tak= e 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 failur= e 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 =3D wait_event_interruptible_timeout(st->wq_data_avail, > st->done, > msecs_to_jiffies(1000)); > - if (ret =3D=3D 0) > - ret =3D -ETIMEDOUT; > - if (ret < 0) { > - mutex_unlock(&st->lock); > - return ret; > - } > - > - *val =3D 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 =3D 0; > - st->done =3D false; > + if (ret > 0) { > + /* a valid conversion took place */ > + *val =3D st->last_value; > + st->last_value =3D 0; > + st->done =3D false; > + ret =3D IIO_VAL_INT; > + } else if (ret =3D=3D 0) { > + /* conversion timeout */ > + dev_err(&idev->dev, "ADC Channel %d timeout.\n", > + chan->channel); > + ret =3D -ETIMEDOUT; > + } > + > mutex_unlock(&st->lock); > - return IIO_VAL_INT; > + return ret; > = > case IIO_CHAN_INFO_SCALE: > *val =3D st->vref_mv; _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel