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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 44F01C48BDE for ; Sun, 7 Jul 2019 19:46:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1849A20663 for ; Sun, 7 Jul 2019 19:46:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728748AbfGGTq4 (ORCPT ); Sun, 7 Jul 2019 15:46:56 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:56876 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727460AbfGGTiB (ORCPT ); Sun, 7 Jul 2019 15:38:01 -0400 Received: from 94.197.121.43.threembb.co.uk ([94.197.121.43] helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1hkCz1-0006dY-Fl; Sun, 07 Jul 2019 20:37:59 +0100 Received: from ben by deadeye with local (Exim 4.92) (envelope-from ) id 1hkCz0-0005Xd-FF; Sun, 07 Jul 2019 20:37:58 +0100 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, Denis Kirjanov , "Jeremy Fertic" , "Jonathan Cameron" Date: Sun, 07 Jul 2019 17:54:17 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 017/129] staging: iio: adt7316: fix the dac write calculation In-Reply-To: X-SA-Exim-Connect-IP: 94.197.121.43 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.70-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Jeremy Fertic commit 78accaea117c1ae878774974fab91ac4a0b0e2b0 upstream. The lsb calculation is not masking the correct bits from the user input. Subtract 1 from (1 << offset) to correctly set up the mask to be applied to user input. The lsb register stores its value starting at the bit 7 position. adt7316_store_DAC() currently assumes the value is at the other end of the register. Shift the lsb value before storing it in a new variable lsb_reg, and write this variable to the lsb register. Fixes: 35f6b6b86ede ("staging: iio: new ADT7316/7/8 and ADT7516/7/9 driver") Signed-off-by: Jeremy Fertic Signed-off-by: Jonathan Cameron Signed-off-by: Ben Hutchings --- drivers/staging/iio/addac/adt7316.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) --- a/drivers/staging/iio/addac/adt7316.c +++ b/drivers/staging/iio/addac/adt7316.c @@ -1448,7 +1448,7 @@ static ssize_t adt7316_show_DAC(struct a static ssize_t adt7316_store_DAC(struct adt7316_chip_info *chip, int channel, const char *buf, size_t len) { - u8 msb, lsb, offset; + u8 msb, lsb, lsb_reg, offset; u16 data; int ret; @@ -1466,9 +1466,13 @@ static ssize_t adt7316_store_DAC(struct return -EINVAL; if (chip->dac_bits > 8) { - lsb = data & (1 << offset); + lsb = data & ((1 << offset) - 1); + if (chip->dac_bits == 12) + lsb_reg = lsb << ADT7316_DA_12_BIT_LSB_SHIFT; + else + lsb_reg = lsb << ADT7316_DA_10_BIT_LSB_SHIFT; ret = chip->bus.write(chip->bus.client, - ADT7316_DA_DATA_BASE + channel * 2, lsb); + ADT7316_DA_DATA_BASE + channel * 2, lsb_reg); if (ret) return -EIO; }