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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 23ADAC2D0DB for ; Fri, 31 Jan 2020 16:26:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F073821734 for ; Fri, 31 Jan 2020 16:26:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726322AbgAaQ0v (ORCPT ); Fri, 31 Jan 2020 11:26:51 -0500 Received: from lhrrgout.huawei.com ([185.176.76.210]:2343 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726114AbgAaQ0u (ORCPT ); Fri, 31 Jan 2020 11:26:50 -0500 Received: from LHREML714-CAH.china.huawei.com (unknown [172.18.7.108]) by Forcepoint Email with ESMTP id BC5B4EA82E605F00057D; Fri, 31 Jan 2020 16:26:48 +0000 (GMT) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by LHREML714-CAH.china.huawei.com (10.201.108.37) with Microsoft SMTP Server (TLS) id 14.3.408.0; Fri, 31 Jan 2020 16:26:48 +0000 Received: from [127.0.0.1] (10.202.226.43) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1713.5; Fri, 31 Jan 2020 16:26:47 +0000 Subject: Re: [PATCH v2 2/3] spi: Add HiSilicon v3xx SPI NOR flash controller driver To: Andy Shevchenko CC: Jiancheng Xue , , Linux Kernel Mailing List , , Linuxarm , linux-spi , Marek Vasut , Mark Brown , "open list:MEMORY TECHNOLOGY..." , , Mika Westerberg , wanghuiqiang , References: <20200110140726.GB5889@sirena.org.uk> <6db83881-927c-d11c-9c77-23a45892ddab@huawei.com> <20200110193119.GI32742@smile.fi.intel.com> <612a3c5d-69a4-af6b-5c79-c3fb853193ab@huawei.com> <20200113114256.GH3897@sirena.org.uk> <6dd45da9-9ccf-45f7-ed12-8f1406a0a56b@huawei.com> <20200113140627.GJ3897@sirena.org.uk> <20200113142754.GL3897@sirena.org.uk> <20200113143403.GQ32742@smile.fi.intel.com> <0252a76d-7e2b-2c70-8b1b-0d041d972098@huawei.com> <136bd652-dcb9-3efa-a92f-2263cbf840ad@huawei.com> From: John Garry Message-ID: Date: Fri, 31 Jan 2020 16:26:46 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.226.43] X-ClientProxiedBy: lhreml735-chm.china.huawei.com (10.201.108.86) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 31/01/2020 15:46, Andy Shevchenko wrote: > On Fri, Jan 31, 2020 at 2:03 PM John Garry wrote: >> On 31/01/2020 11:39, Andy Shevchenko wrote: >>> On Fri, Jan 31, 2020 at 12:08 PM John Garry wrote: >>>> On 13/01/2020 14:34, Andy Shevchenko wrote: > > ... > >>>> About this topic of ACPI having no method to describe device buswidth in >>>> the resource descriptor, it may be an idea for me to raise a Tianocore >>>> feature request @ https://bugzilla.tianocore.org/ >>>> >>> >>> The 19.6.126 describes the SPI resource, in particular: >>> >>> ---8<---8<--- >>> DataBitLength is the size, in bits, of the smallest transfer unit for >>> this connection. _LEN is automatically >>> created to refer to this portion of the resource descriptor. >>> ---8<---8<--- >>> Hi Andy, >>> Is it what you are looking for? (As far as I know most of the >>> firmwares simple abuse this field among others) >> >> I didn't think so - I thought that there was a distinction between width >> and length in SPI terms. > > My interpretation of this field is a data width of the slave. > Basically what we have as transfer->size inside SPI in the Linux > kernel. > >> So how do you find that most firmwares abuse this field? AFAICS, linux >> kernel doesn't interpret this field at all. > >>>From all tables I have this is the result of appearance (some of the > tables are like 10x times present in my data base, but nevertheless) > > 140 SpiSerialBusV2(0x0000,PolarityHigh,FourWireMode,0x08, > 411 SpiSerialBusV2(0x0000,PolarityLow,FourWireMode,0x08, > 1 SpiSerialBusV2(0x0000,PolarityLow,FourWireMode,0x08, > 36 SpiSerialBusV2(0x0000,PolarityLow,FourWireMode,0x10, > 35 SpiSerialBusV2(0x0000,PolarityLow,FourWireMode,0x18, > 35 SpiSerialBusV2(0x0000,PolarityLow,FourWireMode,0x20, > 1 SpiSerialBusV2(0x0000,PolarityLow,ThreeWireMode,0x10, > 8 SpiSerialBusV2(0x0001,PolarityLow,FourWireMode,0x08, > 1 SpiSerialBusV2(0x0001,PolarityLow,FourWireMode,0x10, > > So, it seems I stand corrected, the field is in right use, although > cases like 0x10 and 0x20 should be carefully checked. > > We may teach kernel to get something meaningful out of it. > It seems that someone already had a go at that: https://lore.kernel.org/lkml/20170317212143.bogj6efzyvvf24yd@sirena.org.uk/ Thanks, John