Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754170Ab3HPW0Y (ORCPT ); Fri, 16 Aug 2013 18:26:24 -0400 Received: from mail-ee0-f52.google.com ([74.125.83.52]:48123 "EHLO mail-ee0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752216Ab3HPW0U (ORCPT ); Fri, 16 Aug 2013 18:26:20 -0400 Date: Fri, 16 Aug 2013 22:18:10 +0100 From: "Zubair Lutfullah :" To: Sebastian Andrzej Siewior Cc: Zubair Lutfullah , jic23@cam.ac.uk, dmitry.torokhov@gmail.com, linux-iio@vger.kernel.org, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, Russ.Dill@ti.com Subject: Re: [PATCH 4/4] iio: ti_am335x_adc: Add continuous sampling and trigger support Message-ID: <20130816211809.GA2636@gmail.com> References: <1376424303-22740-1-git-send-email-zubair.lutfullah@gmail.com> <1376424303-22740-5-git-send-email-zubair.lutfullah@gmail.com> <20130816125340.GC1263@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20130816125340.GC1263@linutronix.de> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1834 Lines: 49 On Fri, Aug 16, 2013 at 02:53:40PM +0200, Sebastian Andrzej Siewior wrote: > * Zubair Lutfullah | 2013-08-13 21:05:03 [+0100]: > > >diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c > >index 3ceac3e..0d7e313 100644 > >--- a/drivers/iio/adc/ti_am335x_adc.c > >+++ b/drivers/iio/adc/ti_am335x_adc.c > >@@ -24,16 +24,28 @@ > … > >+static irqreturn_t tiadc_irq(int irq, void *private) > >+{ > >+ struct iio_dev *idev = private; > >+ struct tiadc_device *adc_dev = iio_priv(idev); > >+ unsigned int status, config; > >+ status = tiadc_readl(adc_dev, REG_IRQSTATUS); > >+ > >+ /* FIFO Overrun. Clear flag. Disable/Enable ADC to recover */ > >+ if (status & IRQENB_FIFO1OVRRUN) { > >+ config = tiadc_readl(adc_dev, REG_CTRL); > >+ config &= ~(CNTRLREG_TSCSSENB); > >+ tiadc_writel(adc_dev, REG_CTRL, config); > >+ tiadc_writel(adc_dev, REG_IRQSTATUS, IRQENB_FIFO1OVRRUN | > >+ IRQENB_FIFO1UNDRFLW | IRQENB_FIFO1THRES); > >+ tiadc_writel(adc_dev, REG_CTRL, (config | CNTRLREG_TSCSSENB)); > > I have no idea how other handle this but shouldn't you somehow inform > *anyone* that you lost some samples due to this overrun? > > Sebastian The ref manual states that TSCADC module doesn't recover from overrun interrupts. Thats why the disable enable of the module here to handle the situation. And of course, clearing interrupt flags. The data is lost. Informing someone about lost samples is important indeed. But a print statement in this area causes more overruns. I'm open to some input on how to inform userspace of such a situation. Thanks Zubair -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/