From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752768AbcKIE2q (ORCPT ); Tue, 8 Nov 2016 23:28:46 -0500 Received: from mail-pf0-f193.google.com ([209.85.192.193]:35187 "EHLO mail-pf0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751783AbcKIE2p (ORCPT ); Tue, 8 Nov 2016 23:28:45 -0500 Subject: Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon Djtag driver To: Arnd Bergmann References: <1478101374-18778-1-git-send-email-anurup.m@huawei.com> <22120038.dbaYpsQoUH@wuerfel> <5821D736.7080803@gmail.com> <4657586.c5MJoh65Ux@wuerfel> Cc: linux-arm-kernel@lists.infradead.org, Tan Xiaojun , anurup.m@huawei.com, linux-kernel@vger.kernel.org, mark.rutland@arm.com, shyju.pv@huawei.com, gabriele.paoloni@huawei.com, john.garry@huawei.com, will.deacon@arm.com, linuxarm@huawei.com, xuwei5@hisilicon.com, zhangshaokun@hisilicon.com, sanil.kumar@hisilicon.com, shiju.jose@huawei.com From: Anurup M Message-ID: <5822A5F6.9040806@gmail.com> Date: Wed, 9 Nov 2016 09:58:38 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <4657586.c5MJoh65Ux@wuerfel> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 08 November 2016 08:38 PM, Arnd Bergmann wrote: > On Tuesday, November 8, 2016 7:16:30 PM CET Anurup M wrote: >>>>>> If these are backwards compatible, just mark them as compatible in DT, >>>>>> e.g. hip06 can use >>>>>> >>>>>> compatible = "hisilicon,hip06-cpu-djtag-v1", "hisilicon,hip05-cpu-djtag-v1"; >>>>>> >>>>>> so you can tell the difference if you need to, but the driver only has to >>>>>> list the oldest one here. >>>>>> >>>>>> What is the difference between the cpu and io djtag interfaces? >>>> On some chips like hip06, the djtag version is different for IO die. >>> In what way? The driver doesn't seem to care about the difference. >> There is a difference in djtag version of CPU and IO die (in some chips). >> For ex: in hip06 djtag for CPU is v1 and for IO is v2. >> so they use different readwrite handlers djtag_readwrite_(v1/2). >> >> + /* for hip06(D03) cpu die */ >> + { .compatible = "hisilicon,hip06-cpu-djtag-v1", >> + .data = (void *)djtag_readwrite_v1 }, >> + /* for hip06(D03) io die */ >> + { .compatible = "hisilicon,hip06-io-djtag-v2", >> + .data = (void *)djtag_readwrite_v2 }, >> >> >> For the same djtag version, there is no difference in handling in the >> driver. > Right, but my point was about the compatibility with the older chips > using the same IP block, marking the ones as compatible that actually > use the same interface. > > I also see that the compatible strings have the version included in > them, and you can probably drop them by requiring them only in the > fallback: > > compatible = "hisilicon,hip05-cpu-djtag", "hisilicon,djtag-v1"; > compatible = "hisilicon,hip05-io-djtag", "hisilicon,djtag-v1"; > compatible = "hisilicon,hip06-cpu-djtag", "hisilicon,djtag-v1"; > compatible = "hisilicon,hip06-io-djtag", "hisilicon,djtag-v2"; > compatible = "hisilicon,hip07-cpu-djtag", "hisilicon,djtag-v2"; > compatible = "hisilicon,hip07-io-djtag", "hisilicon,djtag-v2"; > > We want to have the first entry be as specific as possible, but > the last (second) entry is the one that can be used by the driver > for matching. When a future hip08/hip09/... chip uses an existing > interface, you then don't have to update the driver. Thanks. I had a similar thought on this. So as I have the version string in the second entry "-v(1/2)". I can use it in driver for matching. So i think I will change it as below. Please correct me if my understanding is wrong. static const struct of_device_id djtag_of_match[] = { - /* for hip05(D02) cpu die */ - { .compatible = "hisilicon,hip05-cpu-djtag-v1", + /* for hisi djtag-v1 cpu die */ + { .compatible = "hisilicon,hisi-cpu-djtag-v1", .data = djtag_readwrite_v1 }, - /* for hip05(D02) io die */ - { .compatible = "hisilicon,hip05-io-djtag-v1", + /* for hisi djtag-v1 io die */ + { .compatible = "hisilicon,hisi-io-djtag-v1", .data = djtag_readwrite_v1 }, - /* for hip06(D03) cpu die */ - { .compatible = "hisilicon,hip06-cpu-djtag-v1", - .data = djtag_readwrite_v1 }, - /* for hip06(D03) io die */ - { .compatible = "hisilicon,hip06-io-djtag-v2", - .data = djtag_readwrite_v2 }, - /* for hip07(D05) cpu die */ - { .compatible = "hisilicon,hip07-cpu-djtag-v2", + /* for hisi djtag-v2 cpu die */ + { .compatible = "hisilicon,hisi-cpu-djtag-v2", .data = djtag_readwrite_v2 }, - /* for hip07(D05) io die */ - { .compatible = "hisilicon,hip07-io-djtag-v2", + /* for hisi djtag-v2 io die */ + { .compatible = "hisilicon,hisi-io-djtag-v2", .data = (djtag_readwrite_v2 }, {}, }; Thanks, Anurup > Arnd