From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6400CC4724C for ; Fri, 1 May 2020 13:58:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 39031206D6 for ; Fri, 1 May 2020 13:58:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588341533; bh=VsYap1cvGow2jSCcWvjNno49atcuMeOuC56eocJemgs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=2OwBTwFmBNkk0e/2bKel76EgYFYTJljWv0zyQsTODWwFS0XmVqPCgdUlVtm1Sa0sg qFCXUP/ZfxSii2t4gDnA6w86QUYAHm4D8evn/3N7bcCoPadcjmEtBtsoWJAzqybQ5J yaSH74sGNNKV46Z4z27hBRLzGIJ3E9jL/0ri/Ai0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730036AbgEAN6w (ORCPT ); Fri, 1 May 2020 09:58:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:53800 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729848AbgEANaB (ORCPT ); Fri, 1 May 2020 09:30:01 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E710F208DB; Fri, 1 May 2020 13:29:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588339800; bh=VsYap1cvGow2jSCcWvjNno49atcuMeOuC56eocJemgs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WvCIrqsfZu8qMHxmW4T5+hCvr4eOIoFup0VkiGIy4vzda1loqQs07gzAOxOTpeGJZ Ux/VeUtt1VdhCZYV108nhgWrmoBlhSuJ/s6tX6Gf3W4Q9EVUYgWILPuuuN2y925Ifc yBGA/SKuoq467JBov0RwTJAJcDocYg1+tTAjsH24= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ian Abbott Subject: [PATCH 4.9 52/80] staging: comedi: dt2815: fix writing hi byte of analog output Date: Fri, 1 May 2020 15:21:46 +0200 Message-Id: <20200501131529.726360587@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200501131513.810761598@linuxfoundation.org> References: <20200501131513.810761598@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ian Abbott commit ed87d33ddbcd9a1c3b5ae87995da34e6f51a862c upstream. The DT2815 analog output command is 16 bits wide, consisting of the 12-bit sample value in bits 15 to 4, the channel number in bits 3 to 1, and a voltage or current selector in bit 0. Both bytes of the 16-bit command need to be written in turn to a single 8-bit data register. However, the driver currently only writes the low 8-bits. It is broken and appears to have always been broken. Electronic copies of the DT2815 User's Manual seem impossible to find online, but looking at the source code, a best guess for the sequence the driver intended to use to write the analog output command is as follows: 1. Wait for the status register to read 0x00. 2. Write the low byte of the command to the data register. 3. Wait for the status register to read 0x80. 4. Write the high byte of the command to the data register. Step 4 is missing from the driver. Add step 4 to (hopefully) fix the driver. Also add a "FIXME" comment about setting bit 0 of the low byte of the command. Supposedly, it is used to choose between voltage output and current output, but the current driver always sets it to 1. Signed-off-by: Ian Abbott Cc: stable Link: https://lore.kernel.org/r/20200406142015.126982-1-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/drivers/dt2815.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/staging/comedi/drivers/dt2815.c +++ b/drivers/staging/comedi/drivers/dt2815.c @@ -101,6 +101,7 @@ static int dt2815_ao_insn(struct comedi_ int ret; for (i = 0; i < insn->n; i++) { + /* FIXME: lo bit 0 chooses voltage output or current output */ lo = ((data[i] & 0x0f) << 4) | (chan << 1) | 0x01; hi = (data[i] & 0xff0) >> 4; @@ -114,6 +115,8 @@ static int dt2815_ao_insn(struct comedi_ if (ret) return ret; + outb(hi, dev->iobase + DT2815_DATA); + devpriv->ao_readback[chan] = data[i]; } return i;