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 1DC11EE4992 for ; Fri, 18 Aug 2023 21:13:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239873AbjHRVNH (ORCPT ); Fri, 18 Aug 2023 17:13:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52670 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240724AbjHRVM4 (ORCPT ); Fri, 18 Aug 2023 17:12:56 -0400 Received: from mail-lj1-x230.google.com (mail-lj1-x230.google.com [IPv6:2a00:1450:4864:20::230]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E3D29422C for ; Fri, 18 Aug 2023 14:12:46 -0700 (PDT) Received: by mail-lj1-x230.google.com with SMTP id 38308e7fff4ca-2b9b904bb04so21725121fa.1 for ; Fri, 18 Aug 2023 14:12:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1692393165; x=1692997965; h=content-transfer-encoding:in-reply-to:from:content-language :references:to:subject:user-agent:mime-version:date:message-id:from :to:cc:subject:date:message-id:reply-to; bh=oAHS8Yx5ppsocSAwAkbrgjIf+g/MiPV0E0bVjlMzLYw=; b=OfTZ+tSNhJ54voY+0cC2z1fsoZf/amXjCTtMtynsl7NPVbg10dBB6achCZnqTfOD89 aJgBrkCJGMEFtv2TgxALGaajiU3j1kPpOEaiw6PWnYCmyiGipLg255Ku/nPubfrnaCpX IBQy3T6OSLODkuArZabwP5fNVEdROPFqCXl0xjZYEFtycJ7nQHJRs2uOYHzjZHcneT1n 0QeJw1Ss3ZkbgReF/LNhTQIB8illdcBwc/Y7poHJbqGS+57LMP9JPdUKm3ZWX6KkauGf s5Z9mWJ31t5nNtIBe/8dW8dFbQ4U5gzoz01JZCzV88op2v3nQKpF7+uv5zKU6FBMSeFc Ms+w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692393165; x=1692997965; h=content-transfer-encoding:in-reply-to:from:content-language :references:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=oAHS8Yx5ppsocSAwAkbrgjIf+g/MiPV0E0bVjlMzLYw=; b=VjZevkbqbpu01EOjnnuu9c2kH8+8j0fTI+uqu8wP4KXAlw1QNZBDp5feJCjFZUznsZ NmLET841gCGJyq03cBFEOQIfBj2zwCmu/Zy0C8DwA7G9fTe8QFipMJcZ6EWfPuaqjWW7 fFSl1reFG5KToJoFPU1JQopnOBnBhdhGu3pCrMc1xbg0LsIPYLrePRoFGwIML/4Qkzjx lG6fg1c9pULzVcYaOgDLNG9R7iLhRrqbhRTf32+0j43BqUSuJq7nC7erZydYkiZbhjh6 cs3z11x2YH+uA8T2NmaQGQoTjgc5jx6Co+B5X/1XtQtTiH/qTIHuhC3Ugrjampse0YmT zPVQ== X-Gm-Message-State: AOJu0YxarHm/q/trR9wRJAcAovA/KUBzaX5quqBcLJ4zzHSlzKNMKWkg nMs4yMiVcpIc6Jk2XxkbRBM= X-Google-Smtp-Source: AGHT+IHy5rjGw63jPhO7mpRo+1xd3St+FRy6GrBLq19y5Q9ciGsW/sn0ZEU//6tUeJXnLBS8TS3o3A== X-Received: by 2002:a2e:8813:0:b0:2b9:e831:f15f with SMTP id x19-20020a2e8813000000b002b9e831f15fmr245467ljh.32.1692393164827; Fri, 18 Aug 2023 14:12:44 -0700 (PDT) Received: from [192.168.0.131] ([194.183.54.57]) by smtp.gmail.com with ESMTPSA id n5-20020a2e8785000000b002b6df22f0edsm623185lji.64.2023.08.18.14.12.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 18 Aug 2023 14:12:44 -0700 (PDT) Message-ID: Date: Fri, 18 Aug 2023 23:12:43 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [PATCH v3 5/6] leds: turris-omnia: support HW controlled mode via private trigger To: =?UTF-8?Q?Marek_Beh=c3=ban?= , Pavel Machek , Lee Jones , linux-leds@vger.kernel.org References: <20230802160748.11208-1-kabel@kernel.org> <20230802160748.11208-6-kabel@kernel.org> <20230802181345.59d0b0bb@dellmb> Content-Language: en-US From: Jacek Anaszewski In-Reply-To: <20230802181345.59d0b0bb@dellmb> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-leds@vger.kernel.org Hi Marek, On 8/2/23 18:13, Marek Behún wrote: > On Wed, 2 Aug 2023 18:07:47 +0200 > Marek Behún wrote: > >> +static int omnia_hwtrig_activate(struct led_classdev *cdev) >> +{ >> + struct led_classdev_mc *mc_cdev = lcdev_to_mccdev(cdev); >> + struct omnia_leds *leds = dev_get_drvdata(cdev->dev->parent); >> + struct omnia_led *led = to_omnia_led(mc_cdev); >> + int err = 0; >> + >> + mutex_lock(&leds->lock); >> + >> + if (!led->on) { >> + /* >> + * If the LED is off (brightness was set to 0), the last >> + * configured color was not necessarily sent to the MCU. >> + * Recompute with max_brightness and send if needed. >> + */ >> + led_mc_calc_color_components(mc_cdev, cdev->max_brightness); >> + >> + if (omnia_led_channels_changed(led)) >> + err = omnia_led_send_color_cmd(leds->client, led); >> + } >> + >> + if (!err) { >> + /* put the LED into MCU controlled mode */ >> + err = omnia_cmd_write(leds->client, CMD_LED_MODE, >> + CMD_LED_MODE_LED(led->reg)); >> + if (!err) >> + led->hwtrig = true; >> + } >> + >> + mutex_unlock(&leds->lock); >> + >> + return err; >> +} > > Pavel, Lee, here I wanted to ask: can the .activate() method of a LED > trigger sleep? The .brightness_set() method of a LED cannot sleep, and > therefore we have .brightness_set_blocking() method, which schedules > the potentially sleeping call into a work. But there is no such > mechanism for the LED trigger .activate() method. > > I looked at the LED core code, and it does not seem to me that > .activate() sleeping would cause issues, besides keeping trigger list > lock locked... > > Note that previously none of the LED triggers in drivers/leds/trigger > sleeped in .activate(), but recently the ethernet PHY subsystem was > wired into the netdev trigger, which may cause the .activate() method > to do a PHY transfer, which AFAIK may sleep... In general led_set_brightness() can't sleep because it is called from triggers in atomic contexts, which shouldn't be the case for activate(). .activate() is called from led_trigger_{set|remove}() which is called from led_classdev_{register|unregister}) and from sysfs trigger attr's led_trigger_write() handler, so no risk here. Triggers already call e.g. kzalloc() in .activate() which may sleep. -- Best regards, Jacek Anaszewski