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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 A6A5AC83003 for ; Wed, 29 Apr 2020 07:32:47 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 710A9206D6 for ; Wed, 29 Apr 2020 07:32:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ehSyKLh+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 710A9206D6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:35426 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jThD4-0001i4-F0 for qemu-devel@archiver.kernel.org; Wed, 29 Apr 2020 03:32:46 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:46188) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jTh1y-0007tt-S9 for qemu-devel@nongnu.org; Wed, 29 Apr 2020 03:22:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.90_1) (envelope-from ) id 1jTh1i-0003xv-Gv for qemu-devel@nongnu.org; Wed, 29 Apr 2020 03:21:18 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:56736 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jTh1g-0003v2-HQ for qemu-devel@nongnu.org; Wed, 29 Apr 2020 03:21:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588144857; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=yF+PmgERbTWXmJQUaeokDtWDsSNx4xCM1rtQqZprl0M=; b=ehSyKLh+otWHgMR4Rpx2MN/UQkucbt9XrVLIPTCWHGMJXQOJQPdZuhjz88nEecBlgcOI6b kmQ4iRe/2OwT2cQiED407GDyE60/kSC9jz8VMyJ9I1RuwmbHk7meFshRuL/NSHch6oU/mE RknktOpjr6tmGy/P6FcIzi4HNWeQKy8= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-289-ZhFa8XY5PACWZ3LIDjQ3Ug-1; Wed, 29 Apr 2020 03:20:55 -0400 X-MC-Unique: ZhFa8XY5PACWZ3LIDjQ3Ug-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1BBFC80058A for ; Wed, 29 Apr 2020 07:20:55 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-113-6.ams2.redhat.com [10.36.113.6]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DF4EE5D9F1 for ; Wed, 29 Apr 2020 07:20:54 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 7388811358D9; Wed, 29 Apr 2020 09:20:49 +0200 (CEST) From: Markus Armbruster To: qemu-devel@nongnu.org Subject: [PULL 28/32] smbus: Fix spd_data_generate() for number of banks > 2 Date: Wed, 29 Apr 2020 09:20:44 +0200 Message-Id: <20200429072048.29963-29-armbru@redhat.com> In-Reply-To: <20200429072048.29963-1-armbru@redhat.com> References: <20200429072048.29963-1-armbru@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=207.211.31.81; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/04/29 01:28:11 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" spd_data_generate() splits @ram_size bytes into @nbanks RAM banks of 1 << sz_log2 MiB each, like this: size =3D ram_size >> 20; /* work in terms of megabytes */ [...] nbanks =3D 1; while (sz_log2 > max_log2 && nbanks < 8) { sz_log2--; nbanks++; } Each iteration halves the size of a bank, and increments the number of banks. Wrong: it should double the number of banks. The bug goes back all the way to commit b296b664ab "smbus: Add a helper to generate SPD EEPROM data". It can't bite because spd_data_generate()'s current users pass only @ram_size that result in *zero* iterations: machine RAM size #banks type bank size fulong2e 256 MiB 1 DDR 256 MiB sam460ex 2048 MiB 1 DDR2 2048 MiB 1024 MiB 1 DDR2 1024 MiB 512 MiB 1 DDR2 512 MiB 256 MiB 1 DDR2 256 MiB 128 MiB 1 SDR 128 MiB 64 MiB 1 SDR 64 MiB 32 MiB 1 SDR 32 MiB Apply the obvious, minimal fix. I admit I'm tempted to rip out the unused (and obviously untested) feature instead, because YAGNI. Note that this is not the final result, as spd_data_generate() next increases #banks from 1 to 2 if possible. This is done "to avoid a bug in MIPS Malta firmware". We don't even use this function with machine type malta. *Shrug* Signed-off-by: Markus Armbruster Message-Id: <20200422134815.1584-5-armbru@redhat.com> --- hw/i2c/smbus_eeprom.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/i2c/smbus_eeprom.c b/hw/i2c/smbus_eeprom.c index 07fbbf87f1..e199fc8678 100644 --- a/hw/i2c/smbus_eeprom.c +++ b/hw/i2c/smbus_eeprom.c @@ -229,7 +229,7 @@ uint8_t *spd_data_generate(enum sdram_type type, ram_ad= dr_t ram_size) nbanks =3D 1; while (sz_log2 > max_log2 && nbanks < 8) { sz_log2--; - nbanks++; + nbanks *=3D 2; } =20 assert(size =3D=3D (1ULL << sz_log2) * nbanks); --=20 2.21.1