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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,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 C5B2EC4CECE for ; Mon, 14 Oct 2019 10:49:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9AF5420854 for ; Mon, 14 Oct 2019 10:49:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="RMjhVzS3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731305AbfJNKtO (ORCPT ); Mon, 14 Oct 2019 06:49:14 -0400 Received: from fllv0015.ext.ti.com ([198.47.19.141]:52200 "EHLO fllv0015.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731235AbfJNKtO (ORCPT ); Mon, 14 Oct 2019 06:49:14 -0400 Received: from lelv0265.itg.ti.com ([10.180.67.224]) by fllv0015.ext.ti.com (8.15.2/8.15.2) with ESMTP id x9EAnA94083798; Mon, 14 Oct 2019 05:49:10 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1571050150; bh=CO22/vweVUdYki61a8n0uM9ME48CwXyB/hDV+RVN4oU=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=RMjhVzS3ImQaDnsTaTt16b6L6ZSW7UhdttuuVGxn90u2Om5Fkhb90WXomFar68Hha oFaX03A70w7ylblGHwmKMRcgXAAcUeuzwnK3oPNU4ai0AfmuAhwoxk2EGXqOZnBn1n fzqfwk2Dde2zfqpLClBSoxnudBYWyzCsjsAfsGoI= Received: from DLEE108.ent.ti.com (dlee108.ent.ti.com [157.170.170.38]) by lelv0265.itg.ti.com (8.15.2/8.15.2) with ESMTPS id x9EAnA5F129483 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 14 Oct 2019 05:49:10 -0500 Received: from DLEE102.ent.ti.com (157.170.170.32) by DLEE108.ent.ti.com (157.170.170.38) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1713.5; Mon, 14 Oct 2019 05:49:04 -0500 Received: from fllv0040.itg.ti.com (10.64.41.20) by DLEE102.ent.ti.com (157.170.170.32) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1713.5 via Frontend Transport; Mon, 14 Oct 2019 05:49:04 -0500 Received: from [10.250.99.146] (ileax41-snat.itg.ti.com [10.172.224.153]) by fllv0040.itg.ti.com (8.15.2/8.15.2) with ESMTP id x9EAn8ft120141; Mon, 14 Oct 2019 05:49:08 -0500 Subject: Re: [PATCH v5 3/3] leds: Add control of the voltage/current regulator to the LED core To: Pavel Machek , Jacek Anaszewski CC: , , , , References: <20190923102059.17818-1-jjhiblot@ti.com> <20190923102059.17818-4-jjhiblot@ti.com> <3e648fab-638f-4aa0-dda9-8ddba6562751@gmail.com> <20191013120937.GK5653@amd> From: Jean-Jacques Hiblot Message-ID: Date: Mon, 14 Oct 2019 12:49:07 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20191013120937.GK5653@amd> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-leds-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-leds@vger.kernel.org On 13/10/2019 14:09, Pavel Machek wrote: > Hi! > >> I must say I'm not a big fan of this change. >> It adds a bunch of code to the LED core and gives small >> functionality in a reward. It may also influence maximum >> software blinking rate, so I'd rather avoid calling >> regulator_enable/disable when timer trigger is set. >> >> It will of course require more code. >> >> Since AFAIR Pavel was original proponent of this change then >> I'd like to see his opinion before we move on to discussing >> possible improvements to this patch. > Was I? > > Okay, this series looks quite confusing to me. First, 1/3 looks > "interesting" (would have to analyze it way more). > > Second, 3/3... So we have a LED driver _and_ a regulator? So yes, the > chip driving a LED is usually ... voltage/current regulator. What is > second regulator doing there? Is that a common setup? This is quite common with current-sink LED drivers. The setup looks like this: +-----------+ |           | | Regulator | |           +------------------------+ |           |                        | +-----------+                      __|__                                    \   /          +---------------------+    \ / led          |                     |     V          |    Led Driver       |   --+--          |                     |     |          |                     |     |          |                +----------+          |              \      |          |               \     |          |                +    |          |                |    |          +---------------------+                           |                        +--+--+                        /////// Only the regulator usually does not supply only one LED. JJ > > Best regards, > Pavel >