From patchwork Mon Apr 26 12:37:49 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?b?VsOhY2xhdiBLdWJlcm7DoXQ=?= X-Patchwork-Id: 12224231 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 00E66C433B4 for ; Mon, 26 Apr 2021 12:40:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B74676100C for ; Mon, 26 Apr 2021 12:40:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232107AbhDZMku (ORCPT ); Mon, 26 Apr 2021 08:40:50 -0400 Received: from mail-wr1-f48.google.com ([209.85.221.48]:38491 "EHLO mail-wr1-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233509AbhDZMiu (ORCPT ); Mon, 26 Apr 2021 08:38:50 -0400 Received: by mail-wr1-f48.google.com with SMTP id k14so5802866wrv.5; Mon, 26 Apr 2021 05:38:08 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=RA5vvjC6fYjBEhu3hg6HypYCy6fBqYfLd0XqaA1wLzE=; b=Uaj7JirNZVJ+PkG2hmgjXtTC4s1P7ICd7lV5woAPaTdpxwN0CihVSTygzk/qWKNmcv dUp6207I0qqWN8BzQhP6nRt72qUyDyyd+GdnCIUS2okOkG1SBNucDbqqvHOWuObhuK82 i1H/NFhQKi2xSzjOnWImz5GfSC896qUvUiThWoFm/7g+E8NrEopafF15Oqa2fJ/m63g5 nGJOc/D0G9KjAjGZgelyzus7ebyY0joPQP6pgDCCyFJakGKEUPn+x+4AKXibOcg5V8w9 z5p4eGlya017dKNh2dl6VZ5MU3u27qVR7Rpi05nJfBZva7IZhZg4WUNKwoqDxk3Fb6I+ xVGg== X-Gm-Message-State: AOAM532DPmT9SFVcTFKUTqxaIOu+cXXMoydSOZnrzxZ01aOoM+fVK0sB H/iWLrxsThfVcv5wPjei+fM= X-Google-Smtp-Source: ABdhPJzIZ2jBTNwv0QiR/NORErnXtfS2nKvuiQLNff3kRT50nKRfOgyjkThnJl9Zq0gxyDx7ba3jlw== X-Received: by 2002:adf:ff89:: with SMTP id j9mr12702493wrr.416.1619440687704; Mon, 26 Apr 2021 05:38:07 -0700 (PDT) Received: from localhost ([2a02:8308:387:c900:a7b5:b859:9449:c07b]) by smtp.gmail.com with ESMTPSA id u17sm18784168wmq.30.2021.04.26.05.38.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 26 Apr 2021 05:38:07 -0700 (PDT) From: =?utf-8?b?VsOhY2xhdiBLdWJlcm7DoXQ=?= Cc: =?utf-8?b?VsOhY2xhdiBLdWJlcm7DoXQ=?= , Jean Delvare , Guenter Roeck , Jonathan Corbet , linux-hwmon@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 5/5] hwmon: (max31790) Update documentation Date: Mon, 26 Apr 2021 14:37:49 +0200 Message-Id: <20210426123749.899654-5-kubernat@cesnet.cz> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210426123749.899654-1-kubernat@cesnet.cz> References: <20210413025948.901867-1-kubernat@cesnet.cz> <20210426123749.899654-1-kubernat@cesnet.cz> MIME-Version: 1.0 To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-hwmon@vger.kernel.org The conditions for fan fault and its connection to the PWM mode are now documented. The pwm_rate_of_change and fan_window are now mentioned. According to our testing with Sunon PF36281BX-000U-S99, these values are crucial in how RPM mode works and how long it takes for the RPM to stabilize. For example, setting 5000 RPM (the fan goes up to 23000), the pwm_rate_of_change needed to be changed to the lowest possible value, otherwise the chip would just go from pwm 0 to pwm 60 back and forth and never achieving 5000 RPM (and also signaling fan fault). Based on this testing, we found out that the pwm_rate_of_change and fan_window values need to be changed manually by the user, based on the user's exact fan configuration. Signed-off-by: Václav Kubernát --- Documentation/hwmon/max31790.rst | 41 +++++++++++++++++++++++++++++++- 1 file changed, 40 insertions(+), 1 deletion(-) diff --git a/Documentation/hwmon/max31790.rst b/Documentation/hwmon/max31790.rst index 2979addeac8f..6056b67c3a95 100644 --- a/Documentation/hwmon/max31790.rst +++ b/Documentation/hwmon/max31790.rst @@ -30,6 +30,44 @@ monitoring and control of fan RPM as well as detection of fan failure. Six pins are dedicated tachometer inputs. Any of the six PWM outputs can also be configured to serve as tachometer inputs. +About pwm[1-6]_enable +--------------------- +0 - full-speed + The chip doesn't have a specific way to set "full speed", so setting + pwm[1-6]_enable to 0 is just "set PWM mode with 255 duty cycle". +1 - PWM mode + Fan speed is controlled by writing a value to pwm[1-6]. +2 - RPM mode + Fan speed is controlled by writing a value to fan[1-6]_target. + +About fan[1-6]_fault +-------------------- +In PWM (or full-speed) mode, if the input RPM goes below what is set +in fan[1-6]_target, fan[1-6]_fault gets set to 1. In other words, +fan[1-6]_target works as the minimum input RPM before a fan fault goes off. + +In RPM mode, fan fault is set when the fan spins "too slowly" (exact +conditions are in the datasheet). RPM mode depends on four variables: + target_speed: This is set by fan[1-6]_target. + speed_range: This is set automatically when setting target_speed + or manually by fan[1-12]_div. + pwm_rate_of_change: NOT set by the driver. + fan_window: NOT set by the driver. + +The last two values are not set by the driver, because there's no generic way to +compute them. You should set them manually through i2c (in the bootloader for +example). Check the datasheet for details. + +The fan fault value latches, to reset it, set a value to pwm[1-6] +or fan[1-6]_target. + +About fan[1-12]_div +------------------- +This value affects the measurable range of the chip. The driver sets this value +automatically in RPM based on fan[1-6]_target. In PWM mode, you should set this +value manually based on the details from the datasheet. Setting the speed range +is disabled while in RPM mode to prevent overwriting the automatically +calculated value. Sysfs entries ------------- @@ -39,7 +77,8 @@ fan[1-12]_enable RW enable fan speed monitoring fan[1-12]_input RO fan tachometer speed in RPM fan[1-12]_fault RO fan experienced fault fan[1-12]_div RW set the measurable speed range, not available in RPM mode -fan[1-6]_target RW desired fan speed in RPM +fan[1-6]_target RW RPM mode = desired fan speed + PWM mode = minimum fan speed until fault pwm[1-6]_enable RW regulator mode, 0=full speed, 1=manual (pwm) mode, 2=rpm mode setting rpm mode sets fan*_enable to 1 pwm[1-6] RW fan target duty cycle (0-255)