From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vineet Gupta Subject: Re: [PATCH] arc: use little endian accesses Date: Thu, 10 Mar 2016 05:19:37 +0000 Message-ID: References: <1457544064-16167-1-git-send-email-ltrimas@synopsys.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Return-path: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Lada Trimasova , "linux-snps-arc@lists.infradead.org" Cc: "linux-kernel@vger.kernel.org" , "linux-arch@vger.kernel.org" , Alexey Brodkin , Noam Camus List-Id: linux-arch.vger.kernel.org On Thursday 10 March 2016 10:35 AM, Vineet Gupta wrote: > +CC Noam > > On Wednesday 09 March 2016 10:51 PM, Lada Trimasova wrote: >> > Memory access primitives should use cpu_to_le16, cpu_to_le32, le16_to_cpu >> > and le32_to_cpu because it is not really guaranteed that drivers handles >> > any ordering themselves. > That is the driver issue. readxx as API simply returns data in native endianness. > We've had EZChip running big endian and so far and they didn't need this change. > >> > For example, serial port driver doesn't work when kernel is build for >> > arc big endian architecture. > Last I tested Big Endian on SDP with 8250 part + 8250 driver it was working fine. > I presume this is the systemC model for device and standard 8250 driver and very > likely the model is not fixed endian or something. > > Alexey knows about this stuff - this was discussed on lkml back in 2013 when he > was fighting the Xilinx systemAce driver endian issues > Do you need "native-endian" DT entry in nsimosci DT bindings for uart ? From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtprelay2.synopsys.com ([198.182.60.111]:38049 "EHLO smtprelay.synopsys.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750950AbcCJFTj convert rfc822-to-8bit (ORCPT ); Thu, 10 Mar 2016 00:19:39 -0500 From: Vineet Gupta Subject: Re: [PATCH] arc: use little endian accesses Date: Thu, 10 Mar 2016 05:19:37 +0000 Message-ID: References: <1457544064-16167-1-git-send-email-ltrimas@synopsys.com> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-arch-owner@vger.kernel.org List-ID: To: Lada Trimasova , "linux-snps-arc@lists.infradead.org" Cc: "linux-kernel@vger.kernel.org" , "linux-arch@vger.kernel.org" , Alexey Brodkin , Noam Camus Message-ID: <20160310051937.l5vcpZHeu-61Ywn4AvIC5YmUu9PVpr67CzKIYyOQdok@z> On Thursday 10 March 2016 10:35 AM, Vineet Gupta wrote: > +CC Noam > > On Wednesday 09 March 2016 10:51 PM, Lada Trimasova wrote: >> > Memory access primitives should use cpu_to_le16, cpu_to_le32, le16_to_cpu >> > and le32_to_cpu because it is not really guaranteed that drivers handles >> > any ordering themselves. > That is the driver issue. readxx as API simply returns data in native endianness. > We've had EZChip running big endian and so far and they didn't need this change. > >> > For example, serial port driver doesn't work when kernel is build for >> > arc big endian architecture. > Last I tested Big Endian on SDP with 8250 part + 8250 driver it was working fine. > I presume this is the systemC model for device and standard 8250 driver and very > likely the model is not fixed endian or something. > > Alexey knows about this stuff - this was discussed on lkml back in 2013 when he > was fighting the Xilinx systemAce driver endian issues > Do you need "native-endian" DT entry in nsimosci DT bindings for uart ?