From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755690AbdESOt1 (ORCPT ); Fri, 19 May 2017 10:49:27 -0400 Received: from mail-lf0-f47.google.com ([209.85.215.47]:33803 "EHLO mail-lf0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752349AbdESOsb (ORCPT ); Fri, 19 May 2017 10:48:31 -0400 From: Nikita Yushchenko To: Jonathan Cameron , Hartmut Knaack , Lars-Peter Clausen , Peter Meerwald-Stadler , Matt Ranostay , Gregor Boirie , Sanchayan Maity Cc: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Jeff White , Chris Healy , Vladimir Barinov , Nikita Yushchenko Subject: [PATCH 2/4] iio: hi8435: avoid garbage event at first enable Date: Fri, 19 May 2017 17:48:00 +0300 Message-Id: <20170519144802.14427-2-nikita.yoush@cogentembedded.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170519144802.14427-1-nikita.yoush@cogentembedded.com> References: <20170519144802.14427-1-nikita.yoush@cogentembedded.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, driver generates events for channels if new reading differs from previous one. This "previous value" is initialized to zero, which results into event if value is constant-one. Fix that by initializing "previous value" by reading at event enable time. This provides reliable sequence for userspace: - enable event, - AFTER THAT read current value, - AFTER THAT each event will correspond to change. Signed-off-by: Nikita Yushchenko --- drivers/iio/adc/hi8435.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/iio/adc/hi8435.c b/drivers/iio/adc/hi8435.c index cb8e6342eddf..45a92e3e8f2b 100644 --- a/drivers/iio/adc/hi8435.c +++ b/drivers/iio/adc/hi8435.c @@ -141,10 +141,21 @@ static int hi8435_write_event_config(struct iio_dev *idev, enum iio_event_direction dir, int state) { struct hi8435_priv *priv = iio_priv(idev); + int ret; + u32 tmp; + + if (state) { + ret = hi8435_readl(priv, HI8435_SO31_0_REG, &tmp); + if (ret < 0) + return ret; + if (tmp & BIT(chan->channel)) + priv->event_prev_val |= BIT(chan->channel); + else + priv->event_prev_val &= ~BIT(chan->channel); - priv->event_scan_mask &= ~BIT(chan->channel); - if (state) priv->event_scan_mask |= BIT(chan->channel); + } else + priv->event_scan_mask &= ~BIT(chan->channel); return 0; } -- 2.11.0