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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 1E89FC83000 for ; Wed, 29 Apr 2020 20:22:04 +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 E3BC92082E for ; Wed, 29 Apr 2020 20:22:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="AuZ30Ik3"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=lechnology.com header.i=@lechnology.com header.b="HTOA934A" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E3BC92082E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lechnology.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-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=ZPU2q6OKwcrRre54N5/Djri0xPICdhVoYmr2F8fqzOw=; b=AuZ30Ik3reju4gSZGGoUOeqUn 3bvuDqAEcKlkYJ+6B8THF8zX2NHbr97/wzAFkorYn1wfv7j4oDqnECc2fe5OfRn0aWA4p1P6QGx2U ydWXJhBNcErRoait1/NPYiignJtXRXocUmKY5LCQRYoWVxoL/rUqa27AgupBLP4qRV6x9ojHOzedp Jja+qmyUAKuUHPXgIzCLTS/b/+DLqOnWQ8JXC2+NUOddDLPmemhEkTz+IO4EIVWlwSWwGB2/LvHLY /D5cl81AKv3tt7+234DT5otEqH9Xt9iC6ZCcuor3Xg7dxvqRUfp9RbKMF1T7xmPPWuPWwshe8v0Hs YAASUqzGw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jTtDX-00050l-H5; Wed, 29 Apr 2020 20:22:03 +0000 Received: from vern.gendns.com ([98.142.107.122]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jTtDT-0004Rl-VM for linux-arm-kernel@lists.infradead.org; Wed, 29 Apr 2020 20:22:01 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lechnology.com; s=default; h=Content-Transfer-Encoding:Content-Type: In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To:Subject:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=Y8MYBDFCYPC4U8pxIx3v4pRrJy5sBdcHs+qbfFFaKhU=; b=HTOA934A6qy/XJhCXv7JieZkm9 VDL/VwsXQXfZKMgebwhoX79DwCe1dEyeNLemwXBIk8tM5mFwdDDYFvPECAQCzz75BADr6511h+kZm b8xC6rq+M3ApF0SyHRlkvEHJekU7J0f4DZ8eUQvE4QuZoVDF0ga3EBnACXPC9HY9MiFJVOENmdDtj V6tmcJNN1od8LGMdW7BZHbnD6DX6UdWZuMsTjoiZDME+RGH4YX2Cz59VwIWX2x2edHepq3assRPm5 7v+9TI4QaC6GTRJwyxxr7pBa0wkQ6YQmJFqwDC/WN7rMHSh9ev0BsCPqOzmnf/buNsVuHQbXNNHod d6QWNSXQ==; Received: from 108-198-5-147.lightspeed.okcbok.sbcglobal.net ([108.198.5.147]:40316 helo=[192.168.0.134]) by vern.gendns.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.93) (envelope-from ) id 1jTtCd-0005BN-Mc; Wed, 29 Apr 2020 16:21:07 -0400 Subject: Re: [PATCH 0/4] Introduce the Counter character device interface To: William Breathitt Gray , jic23@kernel.org References: From: David Lechner Message-ID: Date: Wed, 29 Apr 2020 15:21:05 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - vern.gendns.com X-AntiAbuse: Original Domain - lists.infradead.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - lechnology.com X-Get-Message-Sender-Via: vern.gendns.com: authenticated_id: davidmain+lechnology.com/only user confirmed/virtual account not confirmed X-Authenticated-Sender: vern.gendns.com: davidmain@lechnology.com X-Source: X-Source-Args: X-Source-Dir: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200429_132200_175838_FB073444 X-CRM114-Status: UNSURE ( 9.17 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kamel.bouhara@bootlin.com, gwendal@chromium.org, alexandre.torgue@st.com, felipe.balbi@linux.intel.com, linux-iio@vger.kernel.org, syednwaris@gmail.com, alexandre.belloni@bootlin.com, linux-kernel@vger.kernel.org, mcoquelin.stm32@gmail.com, patrick.havelange@essensium.com, fabrice.gasnier@st.com, fabien.lahoudere@collabora.com, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 4/29/20 1:11 PM, William Breathitt Gray wrote: > Over the past couple years we have noticed some shortcomings with the > Counter sysfs interface. Although useful in the majority of situations, > there are certain use-cases where interacting through sysfs attributes > can become cumbersome and inefficient. A desire to support more advanced > functionality such as timestamps, multi-axis positioning tables, and > other such latency-sensitive applications, has motivated a reevaluation > of the Counter subsystem. I believe a character device interface will be > helpful for this more niche area of counter device use. Nice to see some progress being made. :-) > > Interaction with Counter character devices occurs via ioctl commands. > This allows userspace applications to access and set counter data using > native C datatypes rather than working through string translations. For most aspects of the counter subsystem, this is not an issue since configuring a counter is not a time-sensitive operation. Instead of ioctls, I was expecting to just be able to read the character device and receive counter events or poll to wait for events similar to how the input subsystem works or how buffers work in the iio subsystem. I'm afraid I don't really see much use in having ioctls that do exactly what sysfs already does. And my intuition tells me that the extra work needed to maintain it will probably cost more than any benefit gained. (Maybe other have a different experience that leads to a different conclusion?) _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel