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=-7.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 0709FC49ED7 for ; Fri, 13 Sep 2019 07:57:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CFFD420830 for ; Fri, 13 Sep 2019 07:57:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ryRgx+jT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727325AbfIMH5L (ORCPT ); Fri, 13 Sep 2019 03:57:11 -0400 Received: from mail-wr1-f66.google.com ([209.85.221.66]:39257 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725446AbfIMH5L (ORCPT ); Fri, 13 Sep 2019 03:57:11 -0400 Received: by mail-wr1-f66.google.com with SMTP id r3so940448wrj.6 for ; Fri, 13 Sep 2019 00:57:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:reply-to:from:date:message-id :subject:to:cc; bh=+/yOZszLKaf9DuLXpXNH++07GcZPakWa5Tih2uKFC7I=; b=ryRgx+jTq3041wljdKgXgmLh1UsyQKTGk4gts6PAdyADs9sB+dhyZEA97wdPT8jGb5 8RPKDGV/Gtcz/vDfeCoxbKwz5nlc6+dG6rles+2RKtAkTJrDOwy8Tq463waSWMe+m0uM CsUfRfygEjo6+VWHCLapaEShIQXhePcSdfuV0AbQyzzq2OifMFuae2iIrlctmAtuTv+D HwSlUocDDQl99r0B5xURv2RpoWUBJ25dcypGPjBWbkoD3xtZ9kcVO+/n5edLYawqQx8D ZE9aEPS8QU3wWHViyF4eY/81TpnsR+RhILxcz/EhXO4xxqaODLLkBqVWPB0Hy/7jJtjK XgeQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:reply-to :from:date:message-id:subject:to:cc; bh=+/yOZszLKaf9DuLXpXNH++07GcZPakWa5Tih2uKFC7I=; b=GuoRVRosS9BZ2HzfMYH3qNOiCBtoq/O8fYlpPFfumDh2OLENacfyzRRCMRhN+RI3tv 61WIKXUqmtFk6YjVK4awKwapylrth3/e7PHQKtwyV5neY2B+oF3fHPuvpwHmYqGGE84q nxS0x5a/Cwo/JmBXNKTmLBP5DkWBa+gNxbXn+GeLaCNNMi60lKj/7B9dkGlZ4kLfIgAM v7K1pFIMOoGbSx6xxfMvik8er01DEiV/eiAryXCqTKaltwiISZrlkj3vEL0mzGl9+C1L nlBSCemgypi+aYCuoMPZ3uuUUN2L/2i/CYtBqcUY+WTeyVfctvjZ84RVCRQjfyjMV0p8 cdOQ== X-Gm-Message-State: APjAAAU6NPpXZfRe7YpB2xfl/i9s1AvcDm1mMo5GGunMsMs7Hy72AtS2 8EjMfYbS5wsRx1dQ0+MMxRzc3kDiYqlsI3NXUIcwsZha X-Google-Smtp-Source: APXvYqxrrAYAk8/PrZafTfiWoHjIdZ+L0VJ0eFz3RCQOEsqollJl/6I8p9mBFg3KXXYWWiuRU2VQv4LnpL/kyE+SH+k= X-Received: by 2002:a5d:5281:: with SMTP id c1mr6626871wrv.339.1568361427336; Fri, 13 Sep 2019 00:57:07 -0700 (PDT) MIME-Version: 1.0 References: <20190912144310.7458-1-andrea.merello@gmail.com> <20190912144310.7458-3-andrea.merello@gmail.com> <3fe869be01ce7c81fd463158c05e0a4a115bdd6a.camel@analog.com> In-Reply-To: <3fe869be01ce7c81fd463158c05e0a4a115bdd6a.camel@analog.com> Reply-To: andrea.merello@gmail.com From: Andrea Merello Date: Fri, 13 Sep 2019 09:56:56 +0200 Message-ID: Subject: Re: [PATCH 2/4] iio: ad7949: fix incorrect SPI xfer len To: "Ardelean, Alexandru" Cc: "Hennerich, Michael" , "lars@metafoo.de" , "jic23@kernel.org" , "pmeerw@pmeerw.net" , "knaack.h@gmx.de" , "linux-iio@vger.kernel.org" , antoine.couret@essensium.com Content-Type: text/plain; charset="UTF-8" Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org Il giorno ven 13 set 2019 alle ore 08:46 Ardelean, Alexandru ha scritto: > > On Thu, 2019-09-12 at 16:43 +0200, Andrea Merello wrote: > > [External] > > > > This driver supports 14-bits and 16-bits devices. All of them have a 14-bit > > configuration registers. All SPI trasfers, for reading AD conversion > > results and for writing the configuration register, fit in two bytes. > > > > The driver always uses 4-bytes xfers which seems at least pointless (maybe > > even harmful). This patch trims the SPI xfer len and the buffer size to > > two bytes. > > > > The length reduction proposal is fine. > > But, this patch raises a question about endianess. > I'm actually wondering here if we need to see about maybe using a __be16 vs u16. > > I'm not that kernel-savy yet about some of these low-level things to be completely sure here. > So, I'd let someone else maybe handle it. Good point.. It seems that indeed not much care has been taken about endianess here.. Probably we need also some le16_to_cpu() and firends.. Maybe another separate patch can be made to take care about endianess later on? BTW Also, the ____cacheline_aligned is a bit scaring :) I don't know what is that for... > > Thanks > Alex > > > Signed-off-by: Andrea Merello > > --- > > drivers/iio/adc/ad7949.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/iio/adc/ad7949.c b/drivers/iio/adc/ad7949.c > > index 518044c31a73..5c2b3446fa4a 100644 > > --- a/drivers/iio/adc/ad7949.c > > +++ b/drivers/iio/adc/ad7949.c > > @@ -54,7 +54,7 @@ struct ad7949_adc_chip { > > u8 resolution; > > u16 cfg; > > unsigned int current_channel; > > - u32 buffer ____cacheline_aligned; > > + u16 buffer ____cacheline_aligned; > > }; > > > > static int ad7949_spi_write_cfg(struct ad7949_adc_chip *ad7949_adc, u16 val, > > @@ -67,7 +67,7 @@ static int ad7949_spi_write_cfg(struct ad7949_adc_chip *ad7949_adc, u16 val, > > struct spi_transfer tx[] = { > > { > > .tx_buf = &ad7949_adc->buffer, > > - .len = 4, > > + .len = 2, > > .bits_per_word = bits_per_word, > > }, > > }; > > @@ -95,7 +95,7 @@ static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val, > > struct spi_transfer tx[] = { > > { > > .rx_buf = &ad7949_adc->buffer, > > - .len = 4, > > + .len = 2, > > .bits_per_word = bits_per_word, > > }, > > };