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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 66F54C433B4 for ; Sun, 9 May 2021 16:55:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3ED496140B for ; Sun, 9 May 2021 16:55:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229934AbhEIQ4J convert rfc822-to-8bit (ORCPT ); Sun, 9 May 2021 12:56:09 -0400 Received: from eu-smtp-delivery-151.mimecast.com ([185.58.85.151]:50170 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229925AbhEIQ4I (ORCPT ); Sun, 9 May 2021 12:56:08 -0400 Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-198-FopczfqiPWaL-OVgYN3BgQ-1; Sun, 09 May 2021 17:54:54 +0100 X-MC-Unique: FopczfqiPWaL-OVgYN3BgQ-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) by AcuMS.aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Sun, 9 May 2021 17:54:52 +0100 Received: from AcuMS.Aculab.com ([fe80::994c:f5c2:35d6:9b65]) by AcuMS.aculab.com ([fe80::994c:f5c2:35d6:9b65%12]) with mapi id 15.00.1497.015; Sun, 9 May 2021 17:54:52 +0100 From: David Laight To: 'Russell King - ARM Linux admin' , Ansuel Smith CC: "stable@vger.kernel.org" , Palmer Dabbelt , Luis Chamberlain , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" Subject: RE: [RESEND PATCH] arm: Enlarge IO_SPACE_LIMIT needed for some SoC Thread-Topic: [RESEND PATCH] arm: Enlarge IO_SPACE_LIMIT needed for some SoC Thread-Index: AQHXRNSfOfqwrTJOkUK/ibckCmgRtKrbXBSg Date: Sun, 9 May 2021 16:54:51 +0000 Message-ID: <4f6e5115e00e4df2a84a57ed0359e907@AcuMS.aculab.com> References: <20210508175537.202-1-ansuelsmth@gmail.com> <20210508185043.GF1336@shell.armlinux.org.uk> <20210509130956.GI1336@shell.armlinux.org.uk> In-Reply-To: <20210509130956.GI1336@shell.armlinux.org.uk> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ... > Well, an obvious question would be: do you really need that much IO > space? PCs have got away with 64K of IO space without having a problem > for years, so 64K per bus should be fine. If you have 3 buses, that > should be 3 * 64K or 192K. Not only that, but most modern PCI (even) cards don't require IO space. Or does this include memory space - which can be much bigger. I have cut one of our FPGA PCIe slaves down from two 8MB BARs to two 1MB ones, with the extra small BARs (eg for MSI-X) the bridge would have allocated 32MB, now 4MB. Fortunately that card only needs to work on x86-64. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)