From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4E0C4606A320 for ; Tue, 27 Oct 2026 16:32:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=JPKkLEjT; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=L/9wjUU8 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Unsubscribe-Post:List-Owner; bh=kvHpdbzr181XbRpEgtV1R2oktcYB29tcS5XHBNv0lQ8=; b=JPKkLEjTO8BJWasWj3x2kNSVFL rC33xF17c4V+viMovfAtKxwF0FbTipwyfaaiuMF20tZv/dRj3eHOawOVEbIOVRaBMhGf00WgODM3o wNUQQJchImrpDsn2zgiy3nBW3FtidFL6YN5TiJ6fKIqbtcpjjnMrXziS4NqgJR6u/VLbYyYQeNm4V dLgc+PNTIW/QH9VYIBBj+arBZ6FAn2wyK7enh7mTRTPD1h4wZYCI+qUsLUafcGamkcWHh51lEEloQ Jj8yeeppLriKBV4zxNjQoOtSb8A1F7Jm1xr+UGZnPDIDBUsRQ+FNUWtunB1h/3mT+dwJHdYYzcujo +APJrc9w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xLk65-00000005MzL-3Eon; Tue, 27 Oct 2026 16:32:25 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xLk63-00000005Myu-3KGO; Tue, 27 Oct 2026 16:32:24 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with UTF8SMTP id 652D540F22; Tue, 27 Oct 2026 16:32:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with UTF8SMTPSA id C18B21F01825; Tue, 27 Oct 2026 16:32:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793118743; bh=kvHpdbzr181XbRpEgtV1R2oktcYB29tcS5XHBNv0lQ8=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=L/9wjUU8d3mrJwpelfh/WNYBeL7ClsTN5Z/FIX9bgBT1bfIhFUN3uaTN0CEBEiPwu QCRNL0gSXhd8ncuR9jPx5QFJNPcHNPAo2d3R8t7++MKn7Z48961Ce4h7KI5UDuxYl3 07CrG3a8hujQ5s9l2pItC+VbFzItUn9n97KARlIuArpKZleglBPKNFp5J5a03ALXbf sg0amAQcUKZC/SyPFhVmBuCHVm0vaQpfcM88JU8TqsFkaVHbuf+VmMkShkS6NfPvvY oESgVQBE981tciY4ny4xpyD9tT8Ki/cRNVBY6Y4XeWq89PigUFKMseSmjmbEXl+SvT n34tFbBgT8Gow== Date: Tue, 27 Oct 2026 17:32:20 +0100 From: Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= To: Andrea della Porta Cc: Guenter Roeck , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Florian Fainelli , Broadcom internal kernel review list , Jonathan Corbet , Shuah Khan , Randy Dunlap , Laurent Pinchart , Gregor Herburger , Stanimir Varbanov , linux-hwmon@vger.kernel.org, devicetree@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-pwm@vger.kernel.org, Gary Guo , Christophe JAILLET Subject: Re: [PATCH RFC 3/4] hwmon: Add driver for Raspberry Pi RP1 fan tachometer Message-ID: References: <0d2249a66732bfce38a2260bee08cd1ba4097e51.1792748690.git.andrea.porta@suse.com> X-Archived-By: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="wczsomz7ltpapr6j" Content-Disposition: inline In-Reply-To: <0d2249a66732bfce38a2260bee08cd1ba4097e51.1792748690.git.andrea.porta@suse.com> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" X-Spam-Status: No, score=-6.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 --wczsomz7ltpapr6j Content-Type: text/plain; protected-headers=v1; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH RFC 3/4] hwmon: Add driver for Raspberry Pi RP1 fan tachometer MIME-Version: 1.0 Hello, On Fri, Oct 23, 2026 at 12:15:56PM +0200, Andrea della Porta wrote: > Add a hardware monitoring driver to support the fan tachometer on the > Raspberry Pi RP1 southbridge, found on the Raspberry Pi 5. >=20 > The RP1 PWM controller block contains specific MMIO registers that hold > the current fan speed in RPM. These registers are periodically updated by > the RP1 internal firmware based on the tachometer pulses. >=20 > Since the Linux PWM subsystem does not currently offer a framework for > exposing integrated hardware tachometer readings, this driver is > implemented as a standalone hwmon device. It parses the > 'raspberrypi,pwm-tachometer' DT property to find the supplier PWM device, > establishes a device link to ensure proper lifecycle management, and uses > RP1-specific PWM functions to retrieve the RPM values. I wonder if the tachometer readout should be a counter driver? That would allow this driver to not be specific to the RP1 hardware. Best regards Uwe --wczsomz7ltpapr6j Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEP4GsaTp6HlmJrf7Tj4D7WH0S/k4FAmrg0hIACgkQj4D7WH0S /k4tWgf/aBdc0sompTuoqGx4glA5Q7tPemfla+YycjTGdxt9ZwZgvezbioJbkniK oTXSogrYNoBat5wjHuBQluVrr7TxDUAYcPemNasPLXXw8YsFbuQ6VkxeNJxnoFLI efQX1S4xPFPOZogKw/pXdFopxrV3J+SGNyNzIKp5CLBHu+MipL78wMBX4W7j2IL8 Fda5MbTg+pbz8BNA5NNmr1xbwLLt+hSSGommcetIOv16gzgyrKd0vZeEtFTsFQSS NQcPN9XQYOp9unKPk1L1FKip3M+uew5pmOyMYgGBhSoSVetzagYc7FF0YQwK6+Ai TrVi1WtPSfetPZ6w6o39mL5AThZ+Pg== =1ZwV -----END PGP SIGNATURE----- --wczsomz7ltpapr6j--