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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 EF8B1ECDE44 for ; Wed, 24 Oct 2018 22:52:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BC87A2075D for ; Wed, 24 Oct 2018 22:52:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BC87A2075D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bootlin.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726804AbeJYHWx (ORCPT ); Thu, 25 Oct 2018 03:22:53 -0400 Received: from mail.bootlin.com ([62.4.15.54]:57611 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726238AbeJYHWw (ORCPT ); Thu, 25 Oct 2018 03:22:52 -0400 Received: by mail.bootlin.com (Postfix, from userid 110) id B0003207F4; Thu, 25 Oct 2018 00:52:51 +0200 (CEST) Received: from bbrezillon (unknown [91.160.177.164]) by mail.bootlin.com (Postfix) with ESMTPSA id D644720766; Thu, 25 Oct 2018 00:52:40 +0200 (CEST) Date: Thu, 25 Oct 2018 00:52:39 +0200 From: Boris Brezillon To: Grygorii Strashko Cc: Wolfram Sang , , Jonathan Corbet , , Greg Kroah-Hartman , Arnd Bergmann , Przemyslaw Sroka , Arkadiusz Golec , Alan Douglas , Bartosz Folta , Damian Kos , Alicja Jurasik-Urbaniak , Cyprian Wronka , Suresh Punnoose , Rafal Ciepiela , Thomas Petazzoni , Nishanth Menon , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , , , Vitor Soares , Geert Uytterhoeven , Linus Walleij , Xiang Lin , , Sekhar Nori , Przemyslaw Gaj , Peter Rosin , Mike Shettel , Stephen Boyd , Joe Perches Subject: Re: [PATCH v9 6/9] i3c: master: Add driver for Cadence IP Message-ID: <20181025005239.15506a63@bbrezillon> In-Reply-To: <380d73a8-2e54-3cee-2fdd-c6e891df93f7@ti.com> References: <20181022133404.2061-1-boris.brezillon@bootlin.com> <20181022133404.2061-7-boris.brezillon@bootlin.com> <20181024202048.7e3534f7@bbrezillon> <99a506e3-d9d5-0d3e-26e1-031447c14857@ti.com> <20181024230432.66dd71df@bbrezillon> <380d73a8-2e54-3cee-2fdd-c6e891df93f7@ti.com> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 24 Oct 2018 17:43:00 -0500 Grygorii Strashko wrote: > On 10/24/18 4:04 PM, Boris Brezillon wrote: > > On Wed, 24 Oct 2018 15:25:17 -0500 > > Grygorii Strashko wrote: > > > >> On 10/24/18 1:20 PM, Boris Brezillon wrote: > >>> Hi Arnd, > >>> > >>> On Mon, 22 Oct 2018 15:34:01 +0200 > >>> Boris Brezillon wrote: > >>> > >>> > >>>> + > >>>> +static void cdns_i3c_master_rd_from_rx_fifo(struct cdns_i3c_master *master, > >>>> + u8 *bytes, int nbytes) > >>>> +{ > >>>> + readsl(master->regs + RX_FIFO, bytes, nbytes / 4); > >>> > >>> Vitor reported a problem with readsl(): this function expects the 2nd > >>> argument to be aligned on 32-bit, which is not guaranteed here. Unless > >>> you see a better solution, I'll switch back to a loop doing: > >>> > >>> for (i = 0; i < nbytes; i += 4) { > >>> u32 tmp = __raw_readl(...); > >> > >> Pls, do not use __raw io. > > > > Except this is exactly what I want here, unless you have a > > replacement for "readl() without a mem-barrier and without endianness > > conversion" > > > > Not sure why endianness is the problem. readl_relaxed? Because we want to read a stream of bytes, and, if we have a CPU that is operating in big-endian (ARM kernels can configured in BE or LE), byte ordering will be messed up (the controller is LE). If I use readl_relaxed(), I'll then have to call cpu_to_le32(), and finally copy the result to the buffer. > Sry, I've missed that this is part of the driver not i3c core, > so minor/ignore. >