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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 5440AC433ED for ; Thu, 22 Apr 2021 02:36:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 304966142F for ; Thu, 22 Apr 2021 02:36:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234375AbhDVChY (ORCPT ); Wed, 21 Apr 2021 22:37:24 -0400 Received: from mailout.easymail.ca ([64.68.200.34]:53574 "EHLO mailout.easymail.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234140AbhDVChV (ORCPT ); Wed, 21 Apr 2021 22:37:21 -0400 Received: from localhost (localhost [127.0.0.1]) by mailout.easymail.ca (Postfix) with ESMTP id 11DED9FEE6; Thu, 22 Apr 2021 02:36:47 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at emo05-pco.easydns.vpn Received: from mailout.easymail.ca ([127.0.0.1]) by localhost (emo05-pco.easydns.vpn [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id jwBa7HQajX4Z; Thu, 22 Apr 2021 02:36:46 +0000 (UTC) Received: from mail.gonehiking.org (c-24-9-64-241.hsd1.co.comcast.net [24.9.64.241]) by mailout.easymail.ca (Postfix) with ESMTPA id 976309FE94; Thu, 22 Apr 2021 02:36:38 +0000 (UTC) Received: from [192.168.1.4] (internal [192.168.1.4]) by mail.gonehiking.org (Postfix) with ESMTP id 679133EE45; Wed, 21 Apr 2021 20:36:37 -0600 (MDT) To: "Maciej W. Rozycki" Cc: Ondrej Zary , "James E.J. Bottomley" , "Martin K. Petersen" , Christoph Hellwig , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org References: <202104182221.21533.linux@zary.sk> From: Khalid Aziz Subject: Re: [PATCH 0/5] Bring the BusLogic host bus adapter driver up to Y2021 Message-ID: Date: Wed, 21 Apr 2021 20:36:37 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/20/21 12:02 PM, Maciej W. Rozycki wrote: > On Mon, 19 Apr 2021, Khalid Aziz wrote: > >>> Khalid: I have skimmed over these documents and I infer 24-bit addressing >>> can be verified with any MultiMaster adapter, including ones that do have >>> 32-bit addressing implemented, by using the legacy Initialize Mailbox HBA >>> command. That could be used to stop Christoph's recent changes for older >>> adapter support removal and replace them with proper fixes for whatever >>> has become broken. Is that something you'd be willing as the driver's >>> maintainer to look into, or shall I? >> >> Do you mean use OpCode 01 (INITIALIZE MAILBOX) to set a 24-bit address >> for mailbox in place of OpCode 81? Verifying the change would be a >> challenge. Do you have an old adapter to test it with? If you do, go >> ahead and make the changes. I will be happy to review. I have only a >> BT-757 adapter. > > Yes, but upon inspection it looks like our driver doesn't use that opcode > and relies solely on 32-bit Mode Initialize Mailbox (0x81) even with ISA > devices. That makes sense as documentation indicates the firmware has > been designed to be unified so that the same binary microcontroller code > runs across all BusLogic MultiMaster devices. > > Anyway given the unified API it should be straightforward to simulate an > older adapter with a newer one, except for host bus protocol differences. > So verifying the workaround for broken BT-445S adapters continues to work > once modernised is not going to be a problem as it can be unconditionally > activated in a debug environment. That would verify correct DMA bounce > buffer operation under the new scheme. > > Verifying actual ISA operations (third-party DMA, etc.) cannot be made > this way, but as I understand the issue there is merely with passing data > structures around and that may not require too much attention beyond > getting things syntactically correct, which I gather someone forgot to do > with a change made a while ago. So that should be doable as well. In theory this sounds reasonable, but without being able to test with a real hardware I would be concerned about making this change. > > NB as noted before I only have a BT-958 readily wired for operation. I > don't expect I have any other BusLogic hardware, but I may yet have to > double-check a stash of hardware I have accumulated over the years. But > that is overseas, so I won't be able to get at it before we're at least > somewhat closer to normality. If all else fails I could possibly buy one. > > I have respun the series now as promised. Does your BT-757 adapter avoid > the issue with trailing allocation somehow? > Well, my only test machine with a legacy PCI slot died some time back. I have been working on putting together a replacement and have now been able to get a working machine with a BT-950 adapter. I have not seen issue with trailing allocation upto 5.12-rc8. I am going to try the top of tree as well to make sure I do not run into this issue. -- Khalid