Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757273Ab3HPWlS (ORCPT ); Fri, 16 Aug 2013 18:41:18 -0400 Received: from mail-ea0-f178.google.com ([209.85.215.178]:53229 "EHLO mail-ea0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757212Ab3HPWlI (ORCPT ); Fri, 16 Aug 2013 18:41:08 -0400 Date: Fri, 16 Aug 2013 22:42:24 +0100 From: "Zubair Lutfullah :" To: Sebastian Andrzej Siewior Cc: Zubair Lutfullah , jic23@cam.ac.uk, dmitry.torokhov@gmail.com, sameo@linux.intel.com, lee.jones@linaro.org, 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 1/4] input: ti_am335x_tsc: correct step mask update after IRQ Message-ID: <20130816214224.GE2636@gmail.com> References: <1376412499-21007-1-git-send-email-zubair.lutfullah@gmail.com> <1376412499-21007-2-git-send-email-zubair.lutfullah@gmail.com> <20130816085350.GA26895@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130816085350.GA26895@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: 1900 Lines: 52 On Fri, Aug 16, 2013 at 10:53:50AM +0200, Sebastian Andrzej Siewior wrote: > * Zubair Lutfullah | 2013-08-13 17:48:16 [+0100]: > > >@@ -316,7 +318,7 @@ static irqreturn_t titsc_irq(int irq, void *dev) > > > > if (irqclr) { > > titsc_writel(ts_dev, REG_IRQSTATUS, irqclr); > >- am335x_tsc_se_update(ts_dev->mfd_tscadc); > >+ am335x_tsc_se_set(ts_dev->mfd_tscadc, ts_dev->step_mask); > > return IRQ_HANDLED; > > } > > return IRQ_NONE; > > titsc_step_config() computes the mask once since it does not change. It > is then assigned via am335x_tsc_se_set() to ->reg_se_cache() and later > always udpated via am335x_tsc_se_update(). This should ensure that ADC's > and TSC's bits are in sync and clear each other out. > Now you call am335x_tsc_se_set() in every irq which adds the TSC's mask > to ->reg_se_cache but why? It was never removed. > > Sebastian The problem is when ADC/TSC are used together. reg_se_cache would get updated with masks in the se_set function in MFD core. >From TSC driver, the TSC steps would be set in the reg_se_cache variable. >From ADC driver, the ADC steps would be set in the reg_se_cache variable. But the ADC masks weren't being cleared from the reg_se_cache variable anywhere. After a while of using ADC/TSC together, the reg_se_cache variable would have FFFF always. Resulting in redundant sampling and data in ADC FIFO0. MFD has received fixes to update the reg_se_cache upon every call to the se_set functions. Thus, the step_mask must be set every time to ensure that it is updated correctly every time. Hope that clears the confusion. This TSC/ADC sharing can be pretty confusing. 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/