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=-8.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 EFB64C4360F for ; Tue, 2 Apr 2019 16:51:08 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 BFD082070D for ; Tue, 2 Apr 2019 16:51:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="asZwjebT" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BFD082070D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=6ffUulTuqaZ8GXAHhQxnc/FzScbF4QQ/0YLAgd3li4k=; b=asZwjebTAwLlUh oP0NeUAJYoTQvIuaFwiMrKPYtW01vPgYxI9isl0x4KwSR4QuevaOp9RsWB0t5V7gLz067RSUesra3 GSxbEpugrOQfkqG6DR/EXfIfyim+Ack5lakCEd8PRaM8OMLxG9S9eOscaFbpaYUERZlwiF23Dmp0n 6UkuaF52oUlfW7Ag31DmNgcCbqqsPg49uIaVq+QCcsNDQmSuOQ7vUtfJpxjK/h3qeqNsaeQA/AQGA hQU5OkgpMXyoeD3VZ994Chggcz+rRYr/fnhd0R93zdgtIFCCgLMeoFW5rIKm3E6r49Ujrby4TlSNB yRG81l4Bq5vbnb/zb74w==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hBMcq-0000za-Cf; Tue, 02 Apr 2019 16:51:04 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hBMcm-0000wJ-KA for linux-arm-kernel@lists.infradead.org; Tue, 02 Apr 2019 16:51:01 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0A21B80D; Tue, 2 Apr 2019 09:50:58 -0700 (PDT) Received: from fuggles.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A6D303F721; Tue, 2 Apr 2019 09:50:56 -0700 (PDT) Date: Tue, 2 Apr 2019 17:50:54 +0100 From: Will Deacon To: Prasad Sodagudi Subject: Re: [PATCH] perf: Change PMCR write to read-modify-write Message-ID: <20190402165054.GB1442@fuggles.cambridge.arm.com> References: <1553134066-20272-1-git-send-email-psodagud@codeaurora.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1553134066-20272-1-git-send-email-psodagud@codeaurora.org> User-Agent: Mutt/1.11.1+86 (6f28e57d73f2) () X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190402_095100_667731_F7EE7B8C X-CRM114-Status: GOOD ( 17.59 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, peterz@infradead.org, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, mingo@redhat.com, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org [+MarkR] On Wed, Mar 20, 2019 at 07:07:46PM -0700, Prasad Sodagudi wrote: > Preserves the bitfields of PMCR_EL0(AArch64) during PMU reset. > Reset routine should write a 1 to PMCR.C and PMCR.P fields only > to reset the counters. Other fields should not be changed > as they could be set before PMU initialization and their > value must be preserved even after reset. > > Signed-off-by: Prasad Sodagudi > --- > arch/arm64/kernel/perf_event.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c > index 4addb38..0c1afdd 100644 > --- a/arch/arm64/kernel/perf_event.c > +++ b/arch/arm64/kernel/perf_event.c > @@ -868,8 +868,8 @@ static void armv8pmu_reset(void *info) > * Initialize & Reset PMNC. Request overflow interrupt for > * 64 bit cycle counter but cheat in armv8pmu_write_counter(). > */ > - armv8pmu_pmcr_write(ARMV8_PMU_PMCR_P | ARMV8_PMU_PMCR_C | > - ARMV8_PMU_PMCR_LC); > + armv8pmu_pmcr_write(armv8pmu_pmcr_read() | ARMV8_PMU_PMCR_P | > + ARMV8_PMU_PMCR_C | ARMV8_PMU_PMCR_LC); No, I don't think this is right at all. Many of these bits are UNKNOWN out of reset, so you're throwing away our means of getting the PMU into a deterministic state. Who is setting which bits that you want to preserve and why? Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel