Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030300AbbDWQ77 (ORCPT ); Thu, 23 Apr 2015 12:59:59 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:44106 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966402AbbDWQ7z (ORCPT ); Thu, 23 Apr 2015 12:59:55 -0400 Message-ID: <55392507.1030103@codeaurora.org> Date: Thu, 23 Apr 2015 12:59:51 -0400 From: Christopher Covington User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:36.0) Gecko/20100101 Thunderbird/36.0 MIME-Version: 1.0 To: Mathieu Poirier CC: Greg KH , "linux-arm-kernel@lists.infradead.org" , linux-api@vger.kernel.org, "linux-kernel@vger.kernel.org" , Kaixu Xia , Chunyan Zhang Subject: Re: [PATCH 10/11] coresight-etm4x: Controls pertaining to the context ID functions References: <1429742451-11465-1-git-send-email-mathieu.poirier@linaro.org> <1429742451-11465-11-git-send-email-mathieu.poirier@linaro.org> <55390B05.1050801@codeaurora.org> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2820 Lines: 61 On 04/23/2015 11:16 AM, Mathieu Poirier wrote: > On 23 April 2015 at 09:08, Christopher Covington wrote: >> Hi Mathieu, >> >> On 04/22/2015 06:40 PM, Mathieu Poirier wrote: >>> From: Pratik Patel >>> >>> Adding sysfs entries to access and configure specifics about the >>> context ID comparator functions. >>> >>> Signed-off-by: Pratik Patel >>> Signed-off-by: Mathieu Poirier >>> --- >>> .../ABI/testing/sysfs-bus-coresight-devices-etm4x | 19 +++ >>> drivers/hwtracing/coresight/coresight-etm4x.c | 187 +++++++++++++++++++++ >>> 2 files changed, 206 insertions(+) >>> >>> diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x b/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x >>> index b5c0456290ab..8b32cb7b9723 100644 >>> --- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x >>> +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x >>> @@ -254,3 +254,22 @@ Date: April 2015 >>> KernelVersion: 4.01 >>> Contact: Mathieu Poirier >>> Description: (RW) Controls the selection of the resources in the trace unit. >>> + >>> +What: /sys/bus/coresight/devices/.etm/ctxid_idx >>> +Date: April 2015 >>> +KernelVersion: 4.01 >>> +Contact: Mathieu Poirier >>> +Description: (RW) Select which context ID comparator to work with. >>> + >>> +What: /sys/bus/coresight/devices/.etm/ctxid_val >>> +Date: April 2015 >>> +KernelVersion: 4.01 >>> +Contact: Mathieu Poirier >>> +Description: (RW) Get/Set the context ID comparator value to trigger on. >> >> If I'm understanding this correctly, ctxid_val is multiplexed using ctxid_idx. >> Why not just have ctxid_val0, ctxid_val1, ...? > > There can be up to 8 of them on the current implementation and who > knows how many more in the future. To me using and index to select > the context ID to work on scaled better and is introducing less > clutter in sysfs. In theory there's a race condition if two tasks are trying to set the index and then the value, which having individually addressable values solves, but I don't anticipate trying to use more than one task to configure tracing. Chris -- Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/