From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934615Ab3DGX27 (ORCPT ); Sun, 7 Apr 2013 19:28:59 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:46663 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934488Ab3DGX26 (ORCPT ); Sun, 7 Apr 2013 19:28:58 -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, "Greg Kroah-Hartman" , "Ian Abbott" Date: Sun, 07 Apr 2013 23:45:42 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [29/74] staging: comedi: s626: fix continuous acquisition In-Reply-To: X-SA-Exim-Connect-IP: 2001:470:1f08:1539:b4b3:7e2a:e2d0:3478 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 3.2.43-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Ian Abbott commit e4317ce877a31dbb9d96375391c1c4ad2210d637 upstream. For the s626 driver, there is a bug in the handling of asynchronous commands on the AI subdevice when the stop source is `TRIG_NONE`. The command should run continuously until cancelled, but the interrupt handler stops the command running after the first scan. The command set-up function `s626_ai_cmd()` contains this code: switch (cmd->stop_src) { case TRIG_COUNT: /* data arrives as one packet */ devpriv->ai_sample_count = cmd->stop_arg; devpriv->ai_continous = 0; break; case TRIG_NONE: /* continous acquisition */ devpriv->ai_continous = 1; devpriv->ai_sample_count = 0; break; } The interrupt handler `s626_irq_handler()` contains this code: if (!(devpriv->ai_continous)) devpriv->ai_sample_count--; if (devpriv->ai_sample_count <= 0) { devpriv->ai_cmd_running = 0; /* ... */ } So `devpriv->ai_sample_count` is only decremented for the `TRIG_COUNT` case, but `devpriv->ai_cmd_running` is set to 0 (and the command stopped) regardless. Fix this in `s626_ai_cmd()` by setting `devpriv->ai_sample_count = 1` for the `TRIG_NONE` case. The interrupt handler will not decrement it so it will remain greater than 0 and the check for stopping the acquisition will fail. Signed-off-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- drivers/staging/comedi/drivers/s626.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/staging/comedi/drivers/s626.c +++ b/drivers/staging/comedi/drivers/s626.c @@ -1882,7 +1882,7 @@ static int s626_ai_cmd(struct comedi_dev case TRIG_NONE: /* continous acquisition */ devpriv->ai_continous = 1; - devpriv->ai_sample_count = 0; + devpriv->ai_sample_count = 1; break; }