From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934779Ab3GRWXg (ORCPT ); Thu, 18 Jul 2013 18:23:36 -0400 Received: from mail-ee0-f51.google.com ([74.125.83.51]:37000 "EHLO mail-ee0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934640Ab3GRWVr (ORCPT ); Thu, 18 Jul 2013 18:21:47 -0400 From: Zubair Lutfullah To: jic23@cam.ac.uk Cc: gregkh@linuxfoundation.org, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, koen@dominion.thruhere.net Subject: [PATCH 09/15] iio: ti_am335x_adc: Avoid double threshold event Date: Thu, 18 Jul 2013 23:21:20 +0100 Message-Id: <1374186086-5015-10-git-send-email-zubair.lutfullah@gmail.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1374186086-5015-1-git-send-email-zubair.lutfullah@gmail.com> References: <1374186086-5015-1-git-send-email-zubair.lutfullah@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Russ Dill The threshold event handler is being called before the FIFO has actually reached the threshold. The current code receives a FIFO threshold event, masks the interrupt, clears the event, and schedules a workqueue. The workqueue is run, it empties the FIFO, and unmasks the interrupt. In the above sequence, after the event is cleared, it immediately retriggers since the FIFO remains beyond the threshold. When the IRQ is unmasked, this triggered event generates another IRQ. However, as the FIFO has just been emptied, it is likely to not contain enough samples. The waits to clear the event until the FIFO has actually been emptied, in the workqueue. The unmasking and masking of the interrupt remains unchanged. Signed-off-by: Russ Dill Signed-off-by: Zubair Lutfullah --- drivers/iio/adc/ti_am335x_adc.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c index 7ac28a9..8dc070d 100644 --- a/drivers/iio/adc/ti_am335x_adc.c +++ b/drivers/iio/adc/ti_am335x_adc.c @@ -183,11 +183,9 @@ static irqreturn_t tiadc_irq(int irq, void *private) if (iio_buffer_enabled(idev)) { if (!work_pending(&adc_dev->poll_work)) schedule_work(&adc_dev->poll_work); - } else { + } else wake_up_interruptible(&adc_dev->wq_data_avail); - } - tiadc_writel(adc_dev, REG_IRQSTATUS, - IRQENB_FIFO1THRES); + return IRQ_HANDLED; } else { return IRQ_NONE; @@ -216,6 +214,8 @@ static void tiadc_poll_handler(struct work_struct *work_s) } buffer->access->store_to(buffer, (u8 *) inputbuffer); + tiadc_writel(adc_dev, REG_IRQSTATUS, + IRQENB_FIFO1THRES); tiadc_writel(adc_dev, REG_IRQENABLE, IRQENB_FIFO1THRES); -- 1.7.9.5