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=-8.6 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,URIBL_BLOCKED, USER_AGENT_SANE_1 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 F0BC7C433DF for ; Tue, 23 Jun 2020 20:18:20 +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 BBC7E20EDD for ; Tue, 23 Jun 2020 20:18:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="hSlHMvvB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BBC7E20EDD 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]:46520 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jnpN6-0002tK-3m for qemu-devel@archiver.kernel.org; Tue, 23 Jun 2020 16:18:20 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57112) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jnpCM-0006Vl-Em for qemu-devel@nongnu.org; Tue, 23 Jun 2020 16:07:14 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:44559 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 1jnpCJ-0007xm-UT for qemu-devel@nongnu.org; Tue, 23 Jun 2020 16:07:13 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1592942829; 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=D8DDXpCiCqgDBIlGB9H8jtR7RVjHz7qjOEHA78Vivlc=; b=hSlHMvvBQTMWJpPJxweBjEEDMEZIjnAvXvWHdgEq/NegI1JpBZi8ECk0ZkfK7S0RMPypj7 YfwJbBAdyLQasxFks6GniAVH/ks1XKswIdWBmzdcHeELxyq1144z4eNo6OI2mpCkMTae74 3YxsJe8TzbxRwr37cXJXl+YEVMQuKmI= 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-481-0N7K-TZPP5SUmDo07VFzzg-1; Tue, 23 Jun 2020 16:07:03 -0400 X-MC-Unique: 0N7K-TZPP5SUmDo07VFzzg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6DA0B10309B1 for ; Tue, 23 Jun 2020 20:07:02 +0000 (UTC) Received: from [10.3.114.107] (ovpn-114-107.phx2.redhat.com [10.3.114.107]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3920E19D82; Tue, 23 Jun 2020 20:07:02 +0000 (UTC) Subject: Re: [PATCH] ibex_uart: fix XOR-as-pow To: Paolo Bonzini , qemu-devel@nongnu.org References: <20200623195441.14646-1-pbonzini@redhat.com> From: Eric Blake Organization: Red Hat, Inc. Message-ID: Date: Tue, 23 Jun 2020 15:07:01 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <20200623195441.14646-1-pbonzini@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=207.211.31.81; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/23 02:54:39 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action 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" On 6/23/20 2:54 PM, Paolo Bonzini wrote: > The xor-as-pow warning in clang actually detected a genuine bug. > Fix it. > > Signed-off-by: Paolo Bonzini > --- > hw/char/ibex_uart.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/hw/char/ibex_uart.c b/hw/char/ibex_uart.c > index 3e0dd9968e..45cd724998 100644 > --- a/hw/char/ibex_uart.c > +++ b/hw/char/ibex_uart.c > @@ -331,7 +331,7 @@ static void ibex_uart_write(void *opaque, hwaddr addr, > if (value & UART_CTRL_NCO) { > uint64_t baud = ((value & UART_CTRL_NCO) >> 16); > baud *= 1000; > - baud /= 2 ^ 20; > + baud >>= 20; Dividing by 1M instead of 22 seems much more logical, indeed :) It's odd that we are scaling up by 1000, down by 1024*1024, then > > s->char_tx_time = (NANOSECONDS_PER_SECOND / baud) * 10; inverting and scaling by 10. I don't know if there is a more succinct way to write the intended transformation. > } But even without reading the hardware manual to see if the resulting scaling is correct, the typo fix is obvious enough to give: Reviewed-by: Eric Blake -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org