From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755102AbaCaACx (ORCPT ); Sun, 30 Mar 2014 20:02:53 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:37332 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754475AbaC3XnF (ORCPT ); Sun, 30 Mar 2014 19:43:05 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "H Hartley Sweeten" , "Ian Abbott" , "Greg Kroah-Hartman" Date: Mon, 31 Mar 2014 00:23:35 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 095/200] staging: comedi: adv_pci1710: fix analog output readback value In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.56-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: H Hartley Sweeten commit 1e85c1ea1ff2a60659e790ef8ec76c7339445841 upstream. The last value written to a analog output channel is cached in the private data of this driver for readback. Currently, the wrong value is cached in the (*insn_write) functions. The current code stores the data[n] value for readback afer the loop has written all the values. At this time 'n' points past the end of the data array. Fix the functions by using a local variable to hold the data being written to the analog output channel. This variable is then used after the loop is complete to store the readback value. The current value is retrieved before the loop in case no values are actually written.. Signed-off-by: H Hartley Sweeten Reviewed-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- drivers/staging/comedi/drivers/adv_pci1710.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) --- a/drivers/staging/comedi/drivers/adv_pci1710.c +++ b/drivers/staging/comedi/drivers/adv_pci1710.c @@ -414,6 +414,7 @@ static int pci171x_insn_write_ao(struct struct comedi_subdevice *s, struct comedi_insn *insn, unsigned int *data) { + unsigned int val; int n, chan, range, ofs; chan = CR_CHAN(insn->chanspec); @@ -429,11 +430,14 @@ static int pci171x_insn_write_ao(struct outw(devpriv->da_ranges, dev->iobase + PCI171x_DAREF); ofs = PCI171x_DA1; } + val = devpriv->ao_data[chan]; - for (n = 0; n < insn->n; n++) - outw(data[n], dev->iobase + ofs); + for (n = 0; n < insn->n; n++) { + val = data[n]; + outw(val, dev->iobase + ofs); + } - devpriv->ao_data[chan] = data[n]; + devpriv->ao_data[chan] = val; return n; @@ -582,6 +586,7 @@ static int pci1720_insn_write_ao(struct struct comedi_subdevice *s, struct comedi_insn *insn, unsigned int *data) { + unsigned int val; int n, rangereg, chan; chan = CR_CHAN(insn->chanspec); @@ -591,13 +596,15 @@ static int pci1720_insn_write_ao(struct outb(rangereg, dev->iobase + PCI1720_RANGE); devpriv->da_ranges = rangereg; } + val = devpriv->ao_data[chan]; for (n = 0; n < insn->n; n++) { - outw(data[n], dev->iobase + PCI1720_DA0 + (chan << 1)); + val = data[n]; + outw(val, dev->iobase + PCI1720_DA0 + (chan << 1)); outb(0, dev->iobase + PCI1720_SYNCOUT); /* update outputs */ } - devpriv->ao_data[chan] = data[n]; + devpriv->ao_data[chan] = val; return n; }