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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4D449C46CA1 for ; Mon, 16 Oct 2023 21:22:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234051AbjJPVWl (ORCPT ); Mon, 16 Oct 2023 17:22:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38282 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233570AbjJPVWi (ORCPT ); Mon, 16 Oct 2023 17:22:38 -0400 Received: from mx1.sberdevices.ru (mx1.sberdevices.ru [37.18.73.165]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C4583AB; Mon, 16 Oct 2023 14:22:34 -0700 (PDT) Received: from p-infra-ksmg-sc-msk01 (localhost [127.0.0.1]) by mx1.sberdevices.ru (Postfix) with ESMTP id A569D100002; Tue, 17 Oct 2023 00:22:30 +0300 (MSK) DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.sberdevices.ru A569D100002 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=salutedevices.com; s=mail; t=1697491350; bh=tE5YoBnt+11PUnXEmb2Dc+agDamwbenbeeGvKIFi5A4=; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type:From; b=a4PBneFVUNr4GSufpFhR9VLKkcuA+Qd49KGJBxmmsLvzRBVyFjFJnnZr4N7z1AmgX glGrFBHF95BAk563w3x7sv+w7CowE0vxneqq0v3M2ISOKgmFjjD1w9a26lmbWx0djb P+MtN60OEmr4cvPDn47Aox3TjSi/GNEsSSAeLmqfCuYdKgJFRzPtqNujCkXS1czQpN rsKClAh+XTv/8a7iIJXY2L63qP7vVJR2viJt3nVJHi/v3HG4tB5WLLkfn3DWZBxsiV H6EqOOrpqEtIGfGpbTH3ZKAiaMumekIjparEqVrgqewxBWf2TjhI64vU4J6ERBIFpT CheH9ZAcD9hYA== Received: from p-i-exch-sc-m01.sberdevices.ru (p-i-exch-sc-m01.sberdevices.ru [172.16.192.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.sberdevices.ru (Postfix) with ESMTPS; Tue, 17 Oct 2023 00:22:30 +0300 (MSK) Received: from [192.168.1.127] (100.64.160.123) by p-i-exch-sc-m01.sberdevices.ru (172.16.192.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.37; Tue, 17 Oct 2023 00:22:30 +0300 Message-ID: <49b1d68c-2f16-2efd-ae24-2e2bd95a094b@salutedevices.com> Date: Tue, 17 Oct 2023 00:22:51 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH v1 09/11] leds: aw200xx: improve autodim calculation method Content-Language: en-US To: Dmitry Rokosov , Andy Shevchenko CC: , , , , , , , , , References: <20231006160437.15627-1-ddrokosov@salutedevices.com> <20231006160437.15627-10-ddrokosov@salutedevices.com> <20231009131808.lzri7z2nvcmkfuu3@CAB-WSD-L081021> <20231009140225.gj7vkmmio5xfvtnk@CAB-WSD-L081021> From: George Stark In-Reply-To: <20231009140225.gj7vkmmio5xfvtnk@CAB-WSD-L081021> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [100.64.160.123] X-ClientProxiedBy: p-i-exch-sc-m01.sberdevices.ru (172.16.192.107) To p-i-exch-sc-m01.sberdevices.ru (172.16.192.107) X-KSMG-Rule-ID: 10 X-KSMG-Message-Action: clean X-KSMG-AntiSpam-Lua-Profiles: 180654 [Oct 16 2023] X-KSMG-AntiSpam-Version: 6.0.0.2 X-KSMG-AntiSpam-Envelope-From: gnstark@salutedevices.com X-KSMG-AntiSpam-Rate: 0 X-KSMG-AntiSpam-Status: not_detected X-KSMG-AntiSpam-Method: none X-KSMG-AntiSpam-Auth: dkim=none X-KSMG-AntiSpam-Info: LuaCore: 540 540 2509a3fe0f7fdc802e7154a32be7c2dd394ab987, p-i-exch-sc-m01.sberdevices.ru:5.0.1,7.1.1;d41d8cd98f00b204e9800998ecf8427e.com:7.1.1;127.0.0.199:7.1.2;salutedevices.com:7.1.1;100.64.160.123:7.1.2, FromAlignment: s, ApMailHostAddress: 100.64.160.123 X-MS-Exchange-Organization-SCL: -1 X-KSMG-AntiSpam-Interceptor-Info: scan successful X-KSMG-AntiPhishing: Clean X-KSMG-LinksScanning: Clean X-KSMG-AntiVirus: Kaspersky Secure Mail Gateway, version 2.0.1.6960, bases: 2023/10/16 20:05:00 #22203970 X-KSMG-AntiVirus-Status: Clean, skipped Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/9/23 17:02, Dmitry Rokosov wrote: > On Mon, Oct 09, 2023 at 04:18:08PM +0300, Dmitry Rokosov wrote: >> On Fri, Oct 06, 2023 at 09:03:47PM +0300, Andy Shevchenko wrote: >>> On Fri, Oct 6, 2023 at 7:05 PM Dmitry Rokosov >>> wrote: >>>> >>>> From: George Stark >>>> >>>> use DIV_ROUND_UP instead of coarse div >>> >>> Please, respect English grammar and punctuation. >>> Refer to macros and functions as func() (note the parentheses). >>> >>> ... >>> >>>> #define AW200XX_REG_DIM2FADE(x) ((x) + 1) >>>> +#define AW200XX_REG_FADE2DIM(fade) \ >>>> + DIV_ROUND_UP((fade) * AW200XX_DIM_MAX, AW200XX_FADE_MAX) >>> >>> Have you checked if the overflow is _now_ possible (compiling on >>> 32-bit platforms as well)? >> >> I suppose we shouldn't carry on about overflow here because the value of >> fade cannot exceed 255, and DIM_MAX is set at 63 >> >> You can find maximum values of fade and dim in the aw200xx driver >> header: >> >> #define AW200XX_DIM_MAX (BIT(6) - 1) >> #define AW200XX_FADE_MAX (BIT(8) - 1) > > I agree that checking if the fade is not greater than FADE_MAX will not > be excessive. The LED subsystem is capable of sending brightness levels > higher than 255 > Probably we should set max_brightness to AW200XX_FADE_MAX in led_classdev when adding leds. -- Best regards George