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=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 C8E49C433E0 for ; Sun, 24 Jan 2021 15:23:54 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 72AAB22DFA for ; Sun, 24 Jan 2021 15:23:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 72AAB22DFA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=FuuP0DXJt5RppRnBpB8y3M1A5A7zPWhWbn3D1zpXkvI=; b=lZQGj2x6kVfpqTBowjuPPnudG 43GlZvr7CeF8H3nivRA3kKlzVJ2odJ49us0LVTNdLRFQkFyzYQlo0WfEpOn/kraf96lc2IT13L2UE QchoGWU72qIpkkcK0TRkdqdn3uOHU8rymNmEu0Mm3qvK1wAjD5RiSrlX5vf4Vz6qIkZsWJ6VpYtSa UVjcTUPILBoStZCoIdhLgNu94dy9pdFbBGe6SGG2tZSNsrWEcoHxsObngTw3SURG5hVpBZDufyKv3 PxtBMV+UJtT+032JBEpEh1ehbMBYk/CrbcjCpfi7vL1QVZjg8W5LT/R+I2hsFUE0+A2/K7UC0TNd3 knqAOV/HA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l3hDd-0004sY-4H; Sun, 24 Jan 2021 15:22:25 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l3hDZ-0004sC-Qh for linux-arm-kernel@lists.infradead.org; Sun, 24 Jan 2021 15:22:22 +0000 Received: from archlinux (cpc108967-cmbg20-2-0-cust86.5-4.cable.virginm.net [81.101.6.87]) (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 E953B22DFA; Sun, 24 Jan 2021 15:22:16 +0000 (UTC) Date: Sun, 24 Jan 2021 15:22:12 +0000 From: Jonathan Cameron To: Ahmad Fatoum Subject: Re: [PATCH v2] iio: adc: stm32-adc: enable timestamping for non-DMA usage Message-ID: <20210124152212.5bc39e57@archlinux> In-Reply-To: <20210122113355.32384-1-a.fatoum@pengutronix.de> References: <20210122113355.32384-1-a.fatoum@pengutronix.de> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210124_102221_976776_7F784382 X-CRM114-Status: GOOD ( 30.01 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Lars-Peter Clausen , Holger Assmann , Maxime Coquelin , linux-iio@vger.kernel.org, Peter Meerwald-Stadler , linux-kernel@vger.kernel.org, Fabrice Gasnier , kernel@pengutronix.de, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, Alexandre Torgue Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, 22 Jan 2021 12:33:55 +0100 Ahmad Fatoum wrote: > For non-DMA usage, we have an easy way to associate a timestamp with a > sample: iio_pollfunc_store_time stores a timestamp in the primary > trigger IRQ handler and stm32_adc_trigger_handler runs in the IRQ thread > to push out the buffer along with the timestamp. > > For this to work, the driver needs to register an IIO_TIMESTAMP channel. > Do this. > > For DMA, it's not as easy, because we don't push the buffers out of > stm32_adc_trigger, but out of stm32_adc_dma_buffer_done, which runs in > a tasklet scheduled after a DMA completion. > > Preferably, the DMA controller would copy us the timestamp into that buffer > as well. Until this is implemented, restrict timestamping support to > only PIO. For low-frequency sampling, PIO is probably good enough. > > Cc: Holger Assmann > Acked-by: Fabrice Gasnier > Signed-off-by: Ahmad Fatoum This patch itself is fine, but it will expose a potential bug. The buffer passed to iio_push_to_buffers_with_timestamp needs to be suitably aligned to take an 8 byte timestamp and large enough to do so. Currently, in this driver it isn't. u16 buffer[STM32_ADC_MAX_SQ]; Appears to be the same length as the channel count, and isn't 8 byte aligned. (add __aligned(8) to fix that) Could you add that fix to this patch as well? Thanks, Jonathan > --- > v1 -> v2: > - Added comment about timestamping being PIO only (Fabrice) > - Added missing DMA resource clean up in error path (Fabrice) > - Added Fabrice's Acked-by > --- > drivers/iio/adc/stm32-adc.c | 35 +++++++++++++++++++++++++++++------ > 1 file changed, 29 insertions(+), 6 deletions(-) > > diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c > index c067c994dae2..885bb514503c 100644 > --- a/drivers/iio/adc/stm32-adc.c > +++ b/drivers/iio/adc/stm32-adc.c > @@ -1718,7 +1718,7 @@ static void stm32_adc_chan_init_one(struct iio_dev *indio_dev, > } > } > > -static int stm32_adc_chan_of_init(struct iio_dev *indio_dev) > +static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping) > { > struct device_node *node = indio_dev->dev.of_node; > struct stm32_adc *adc = iio_priv(indio_dev); > @@ -1766,6 +1766,9 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev) > return -EINVAL; > } > > + if (timestamping) > + num_channels++; > + > channels = devm_kcalloc(&indio_dev->dev, num_channels, > sizeof(struct iio_chan_spec), GFP_KERNEL); > if (!channels) > @@ -1816,6 +1819,19 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev) > stm32_adc_smpr_init(adc, channels[i].channel, smp); > } > > + if (timestamping) { > + struct iio_chan_spec *timestamp = &channels[scan_index]; > + > + timestamp->type = IIO_TIMESTAMP; > + timestamp->channel = -1; > + timestamp->scan_index = scan_index; > + timestamp->scan_type.sign = 's'; > + timestamp->scan_type.realbits = 64; > + timestamp->scan_type.storagebits = 64; > + > + scan_index++; > + } > + > indio_dev->num_channels = scan_index; > indio_dev->channels = channels; > > @@ -1875,6 +1891,7 @@ static int stm32_adc_probe(struct platform_device *pdev) > struct device *dev = &pdev->dev; > irqreturn_t (*handler)(int irq, void *p) = NULL; > struct stm32_adc *adc; > + bool timestamping = false; > int ret; > > if (!pdev->dev.of_node) > @@ -1931,16 +1948,22 @@ static int stm32_adc_probe(struct platform_device *pdev) > if (ret < 0) > return ret; > > - ret = stm32_adc_chan_of_init(indio_dev); > - if (ret < 0) > - return ret; > - > ret = stm32_adc_dma_request(dev, indio_dev); > if (ret < 0) > return ret; > > - if (!adc->dma_chan) > + if (!adc->dma_chan) { > + /* For PIO mode only, iio_pollfunc_store_time stores a timestamp > + * in the primary trigger IRQ handler and stm32_adc_trigger_handler > + * runs in the IRQ thread to push out buffer along with timestamp. > + */ > handler = &stm32_adc_trigger_handler; > + timestamping = true; > + } > + > + ret = stm32_adc_chan_of_init(indio_dev, timestamping); > + if (ret < 0) > + goto err_dma_disable; > > ret = iio_triggered_buffer_setup(indio_dev, > &iio_pollfunc_store_time, handler, _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel