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=-15.5 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 2AB38C433DB for ; Sun, 24 Jan 2021 15:23:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EF37622DFA for ; Sun, 24 Jan 2021 15:23:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725948AbhAXPXB (ORCPT ); Sun, 24 Jan 2021 10:23:01 -0500 Received: from mail.kernel.org ([198.145.29.99]:36426 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725880AbhAXPXA (ORCPT ); Sun, 24 Jan 2021 10:23:00 -0500 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 Cc: Lars-Peter Clausen , Peter Meerwald-Stadler , Maxime Coquelin , Alexandre Torgue , kernel@pengutronix.de, Holger Assmann , Fabrice Gasnier , linux-iio@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org 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 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.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,