From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lelv0142.ext.ti.com (lelv0142.ext.ti.com [198.47.23.249]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BC48FB670; Mon, 5 Feb 2024 05:55:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.47.23.249 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707112534; cv=none; b=IX0IH7P7egq2N3AARu9dX0qU10fNB+E7hMERmmQ/5lQE1hQ68JS7fEhjg2NQZYwyCOffAq7S+KnkVpXBu0cf387mwCpvEV5c3/P7dPqvto2WSTYX5NTbEGeyEkTtsVDr4nG+M3AhWaFxiCxlorXtHbgiSVFdMJDqtIpaaFE8iaY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707112534; c=relaxed/simple; bh=ju6YE0oBHIeK9zcvvq+qvKrPJsFzxoBtpAAHRsRvN80=; h=Date:From:To:CC:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=tPF1QQMREAJU/MBwMyX6mhlfC1uKFsqWjxHn8yL0FnDIB5HcpUr9xJG9C+j3V5LT+an/xWUg+XREEmPTx9MskBAqVzHB1lkG2Z/29CLmMfGzg4FYsWIXtLbXUv9+rJgaK6HgZXlmnWz/XPWc2TfmADJ8UlU9QVTI1iZ3cysKvo4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=ti.com; spf=pass smtp.mailfrom=ti.com; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b=SwhvQZio; arc=none smtp.client-ip=198.47.23.249 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=ti.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ti.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="SwhvQZio" Received: from lelv0265.itg.ti.com ([10.180.67.224]) by lelv0142.ext.ti.com (8.15.2/8.15.2) with ESMTP id 4155tGiV120696; Sun, 4 Feb 2024 23:55:16 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1707112516; bh=LvEJrWyHyN0lxHNcqKJjNjH0q34jTFfI5LghukRsGIg=; h=Date:From:To:CC:Subject:References:In-Reply-To; b=SwhvQZiozpvh0Xe3ph2T/TA7tWW85Ay4lv2lMBijRRUUeGz2GVCltUJPv6YbVC7+9 ccNiLx/2CARmJrSag5T2EUrsnR8DvZJviK0DxT3le9KHe+4LUtFgtgACamJ+OGhtAg +cb0AK2uz+SMMumbJRX5WGq4BL6HcQ1261lUvHp4= Received: from DLEE109.ent.ti.com (dlee109.ent.ti.com [157.170.170.41]) by lelv0265.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 4155tGBF001855 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Sun, 4 Feb 2024 23:55:16 -0600 Received: from DLEE115.ent.ti.com (157.170.170.26) by DLEE109.ent.ti.com (157.170.170.41) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.23; Sun, 4 Feb 2024 23:55:15 -0600 Received: from lelvsmtp6.itg.ti.com (10.180.75.249) by DLEE115.ent.ti.com (157.170.170.26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.23 via Frontend Transport; Sun, 4 Feb 2024 23:55:15 -0600 Received: from localhost (dhruva.dhcp.ti.com [172.24.227.68]) by lelvsmtp6.itg.ti.com (8.15.2/8.15.2) with ESMTP id 4155tFDn117159; Sun, 4 Feb 2024 23:55:15 -0600 Date: Mon, 5 Feb 2024 11:25:14 +0530 From: Dhruva Gole To: Stefan Wahren CC: Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= , Rob Herring , Krzysztof Kozlowski , Conor Dooley , , Angelo Compagnucci , Philip Howard , Sean Young , Linus Walleij , , , , Subject: Re: [PATCH V4 0/2] pwm: Add GPIO PWM driver Message-ID: <20240205055514.rox6yd2eenhsngva@dhruva> References: <20240204220851.4783-1-wahrenst@gmx.net> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20240204220851.4783-1-wahrenst@gmx.net> X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Hi, On Feb 04, 2024 at 23:08:49 +0100, Stefan Wahren wrote: > Add a software PWM which toggles a GPIO from a high-resolution timer. > > Recent discussions in the Raspberry Pi community revealt that a lot > of users still use MMIO userspace tools for GPIO access. One argument > for this approach is the lack of a GPIO PWM kernel driver. So this > series tries to fill this gap. > > This continues the work of Vincent Whitchurch [1], which is easier > to read and more consequent by rejecting sleeping GPIOs than Nicola's > approach [2]. > > The work has been tested on a Raspberry Pi 3 B+ and a cheap logic > analyzer. I recently came across this series and I have to say that it will sure be a nice to have feature to be able to use any GPIO as a PWM. However, just a minor suggestion is that we should make sure it's well documented how to actually use this. It would be much appreciated if you could include some basic documentation of a few sysfs commands or any userspace library that you used to test what you've mentioned above. Maybe add another patch for this page? https://docs.kernel.org/driver-api/pwm.html#using-pwms-with-the-sysfs-interface This will ensure people know about this feature and will actually be able to use it. -- Best regards, Dhruva Gole