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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 250C7C433FE for ; Wed, 29 Sep 2021 10:00:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 03F8C613D0 for ; Wed, 29 Sep 2021 10:00:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245254AbhI2KBs (ORCPT ); Wed, 29 Sep 2021 06:01:48 -0400 Received: from www381.your-server.de ([78.46.137.84]:52692 "EHLO www381.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245245AbhI2KBs (ORCPT ); Wed, 29 Sep 2021 06:01:48 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=metafoo.de; s=default2002; h=Content-Transfer-Encoding:Content-Type:In-Reply-To: MIME-Version:Date:Message-ID:From:References:Cc:To:Subject:Sender:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID; bh=1WjBcHbtUHWwynb8HCYwJabWRtgbg4lrsK8hlGVcLMI=; b=f1evM4TI1bcX9clqH5czWYaIgd k3LQLnxdvJqhmvWCfCXt/ioxAOA67GoC/wZe4uYWHgV7J2qIm8uvGa3mD3wiafscpj9losoih54I3 LA1qT6bOilB5TFWLsAhFwG5UOt6IOK/ngiwVUCD3qovwoJhBNhiTUZvVsgRWrQDisBWBD1fW9UAMi VfNLNgnnVJ0fTyJyOkaC9Q+J0pESTGkMpYM+Kx354SulHYCnHhT3odFfDPfs0GxYkNy5fgVe0FBYh tiyna+k21z9SGlIkpexEn31zzoF4e8zv7Ht25jIX7B3mnJv7zbrS5KvWAuIEQOc5NToBf/TeQ1ulh b/2RDeiw==; Received: from sslproxy05.your-server.de ([78.46.172.2]) by www381.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92.3) (envelope-from ) id 1mVWNc-0001Nh-Ev; Wed, 29 Sep 2021 12:00:00 +0200 Received: from [82.135.83.152] (helo=[192.168.178.20]) by sslproxy05.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1mVWNc-000Rpa-55; Wed, 29 Sep 2021 12:00:00 +0200 Subject: Re: [PATCH] iio: dac: ad5446: Fix ad5622_write() return value To: Pekka Korpinen Cc: Michael Hennerich , Jonathan Cameron , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210928195548.17846-1-pekka.korpinen@iki.fi> From: Lars-Peter Clausen Message-ID: <20d11fbb-ba93-802c-1abc-60d7f5ec0c0c@metafoo.de> Date: Wed, 29 Sep 2021 11:59:59 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20210928195548.17846-1-pekka.korpinen@iki.fi> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Authenticated-Sender: lars@metafoo.de X-Virus-Scanned: Clear (ClamAV 0.103.3/26306/Tue Sep 28 11:05:37 2021) Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org On 9/28/21 9:55 PM, Pekka Korpinen wrote: > On success i2c_master_send() returns the number of bytes written. The > call from iio_write_channel_info(), however, expects the return value to > be zero on success. > > Signed-off-by: Pekka Korpinen > --- > This bug causes incorrect consumption of the sysfs buffer in > iio_write_channel_info(). When writing more than two characters to > out_voltage0_raw, the ad5446 write handler is called multiple times > causing unexpected behavior. I'd put this into the commit message itself. This is useful information that should be part of the commit log. > > A similar fix was applied for ad5064.c in 2015 - commit 03fe472ef33b > ("iio:ad5064: Make sure ad5064_i2c_write() returns 0 on success"). > > drivers/iio/dac/ad5446.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/iio/dac/ad5446.c b/drivers/iio/dac/ad5446.c > index 488ec69967d6..dfd541bbde5b 100644 > --- a/drivers/iio/dac/ad5446.c > +++ b/drivers/iio/dac/ad5446.c > @@ -531,8 +531,13 @@ static int ad5622_write(struct ad5446_state *st, unsigned val) > { > struct i2c_client *client = to_i2c_client(st->dev); > __be16 data = cpu_to_be16(val); > + int ret; > + > + ret = i2c_master_send(client, (char *)&data, sizeof(data)); > + if (ret < 0) > + return ret; Like you wrote in the commit message the function returns the number of bytes written. We should check that this matches the number of bytes we wanted to send and return an error (EIO) otherwise. > > - return i2c_master_send(client, (char *)&data, sizeof(data)); > + return 0; > } > > /*