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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 535D3FF885C for ; Sun, 26 Apr 2026 10:10:13 +0000 (UTC) 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:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=sxbl4epg48KUX2MzjpAavq4/tG2sfpxD57DOODEbyl0=; b=3LI5MYjNzQtIDZx39cYoS9dlzw +VETDLrRXTrAd+d1t+rFyzEKurzcwIjxWf/Nl2iaiHK9aua3nmNkrXcxjngwRUQmLO+1i3enq3/vz l1RDYLEsxUznx9oHOw1hcrhOKufPJrp+ozGuzg7qshjxqbf3ZSwp7jcjK9udmAVuEg40kDV5B2MvE DOcdoV3ncxWFcYhM3JT2nJ72gbbmOEXp1nb4S+1mhZE6VJcMqGG66e9ZlYDlUL7nWYbQ01NwyWsHE nybJOlqeB0METGwyE2EdWH+4ZMT2UpG1vTVZmgmiZT0xMGg/wGRlHpM9OpyflH/P1irOdvxTQBvzD 5ACADiag==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wGwRD-0000000FQpa-1IWB; Sun, 26 Apr 2026 10:10:07 +0000 Received: from mail-m128112.netease.com ([103.209.128.112]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1wGwR9-0000000FQp2-0lpP; Sun, 26 Apr 2026 10:10:05 +0000 Received: from [172.16.12.43] (unknown [58.22.7.114]) by smtp.qiye.163.com (Hmail) with ESMTP id 3c2b8e6e5; Sun, 26 Apr 2026 18:09:58 +0800 (GMT+08:00) Message-ID: <544c8d66-b242-4895-b8de-2f1dfdd0c7b4@rock-chips.com> Date: Sun, 26 Apr 2026 18:09:59 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 3/6] pwm: Add rockchip PWMv4 driver To: Nicolas Frattaroli , =?UTF-8?Q?Uwe_Kleine-K=C3=B6nig?= , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Heiko Stuebner , Lee Jones , William Breathitt Gray Cc: kernel@collabora.com, Jonas Karlman , Alexey Charkov , linux-rockchip@lists.infradead.org, linux-pwm@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org References: <20260420-rk3576-pwm-v5-0-ae7cfbbe5427@collabora.com> <20260420-rk3576-pwm-v5-3-ae7cfbbe5427@collabora.com> Content-Language: en-US From: Damon Ding In-Reply-To: <20260420-rk3576-pwm-v5-3-ae7cfbbe5427@collabora.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-HM-Tid: 0a9dc9446f9103a3kunm6b0f68e1145d79 X-HM-MType: 1 X-HM-Spam-Status: e1kfGhgUHx5ZQUpXWQgPGg8OCBgUHx5ZQUlOS1dZFg8aDwILHllBWSg2Ly tZV1koWUFDSUNOT01LS0k3V1kYFggdWUFKV1ktWUFJV1kPCRoVCBIfWUFZQh5KTlZPHh0aGBkaTU MdQhpWFRQJFhoXVRMBExYaEhckFA4PWVdZGBILWUFZTkNVSUlVTFVKSk9ZV1kWGg8SFR0UWUFZT0 tIVUpLSU9PT0hVSktLVUpCS0tZBg++ DKIM-Signature: a=rsa-sha256; b=eb4I3kZaySR2+F0gMBqA+RVFFlrWOKdh4b1SAYLJKcnbvJzdFS3sxr68WQO9M8q2IYHeje3rvXLc0fvoKnlmY70h3B0YqxEyL/k1lwEJe3P43wERT4kvuBmCEXLea3V6AmnaLYA6wjfjEaWn+q21PmIEP8kRvTgW6DbdSnvdcoQ=; c=relaxed/relaxed; s=default; d=rock-chips.com; v=1; bh=sxbl4epg48KUX2MzjpAavq4/tG2sfpxD57DOODEbyl0=; h=date:mime-version:subject:message-id:from; X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260426_031003_792296_689E6886 X-CRM114-Status: GOOD ( 31.50 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Nicolas， On 4/20/2026 9:52 PM, Nicolas Frattaroli wrote: > The Rockchip RK3576 brings with it a new PWM IP, in downstream code > referred to as "v4". This new IP is different enough from the previous > Rockchip IP that I felt it necessary to add a new driver for it, instead > of shoehorning it in the old one. > > Add this new driver, based on the PWM core's waveform APIs. Its platform > device is registered by the parent mfpwm driver, from which it also > receives a little platform data struct, so that mfpwm can guarantee that > all the platform device drivers spread across different subsystems for > this specific hardware IP do not interfere with each other. > > Signed-off-by: Nicolas Frattaroli > --- > MAINTAINERS | 1 + > drivers/pwm/Kconfig | 11 ++ > drivers/pwm/Makefile | 1 + > drivers/pwm/pwm-rockchip-v4.c | 383 ++++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 396 insertions(+) > ...... > diff --git a/drivers/pwm/pwm-rockchip-v4.c b/drivers/pwm/pwm-rockchip-v4.c > new file mode 100644 > index 000000000000..b7de72c433c5 > --- /dev/null > +++ b/drivers/pwm/pwm-rockchip-v4.c > @@ -0,0 +1,383 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > +/* > + * Copyright (c) 2025 Collabora Ltd. > + * > + * A Pulse-Width-Modulation (PWM) generator driver for the generators found in > + * Rockchip SoCs such as the RK3576, internally referred to as "PWM v4". Uses > + * the MFPWM infrastructure to guarantee exclusive use over the device without > + * other functions of the device from different drivers interfering with its > + * operation while it's active. > + * > + * Technical Reference Manual: Chapter 31 of the RK3506 TRM Part 1, a SoC which > + * uses the same PWM hardware and has a publicly available TRM. > + * https://opensource.rock-chips.com/images/3/36/Rockchip_RK3506_TRM_Part_1_V1.2-20250811.pdf > + * > + * Authors: > + * Nicolas Frattaroli > + * > + * Limitations: > + * - The hardware supports both completing the currently running period > + * on disable (by switching to oneshot mode with a single repetition and > + * only disable when the complete irq fires), and abrupt disable (freeze). > + * Only the latter is implemented in the driver. > + * - When the output is disabled, the pin will remain driven to whatever state > + * it last had. This limitation exists because after disabling the PWM output via registers, the actual shutdown only happens after the current period completes. Therefore, the better approach is to add a delay of one full period before disabling &rockchip_mfpwm_func.core. > + * - Adjustments to the duty cycle will only take effect during the next period. > + * - Adjustments to the period length will only take effect during the next > + * period. > + * - The hardware only supports offsets in [0, period - duty_cycle] > + */ > + ...... > + > + if (wfhw->rate) { > + if (!was_enabled) { > + dev_dbg(&chip->dev, "Enabling PWM output\n"); > + ret = clk_enable(pc->pwmf->core); > + if (ret) > + goto err_mfpwm_release; > + ret = clk_set_rate_exclusive(pc->pwmf->core, wfhw->rate); > + if (ret) { > + clk_disable(pc->pwmf->core); > + goto err_mfpwm_release; > + } > + > + /* > + * Output should be on now, acquire device to guarantee > + * exclusion with other device functions while it's on. > + * > + * It's highly unlikely that this fails, as mfpwm has > + * already been acquired before, and this is just a > + * usage counter increase. Not worth the added > + * complexity of clearing the PWMV4_REG_ENABLE again, > + * especially considering the CTRL_UPDATE_EN behaviour. > + */ > + ret = mfpwm_acquire(pc->pwmf); > + if (ret) { > + clk_rate_exclusive_put(pc->pwmf->core); > + clk_disable(pc->pwmf->core); > + goto err_mfpwm_release; > + } > + } > + } else if (was_enabled) { > + dev_dbg(&chip->dev, "Disabling PWM output\n"); Delay for one full PWM period before disabling the dclk. Although this may introduce some latency for disable -> re-enable operations, it ensures that the state after shutdown aligns with the actual polarity configuration. > + clk_rate_exclusive_put(pc->pwmf->core); > + clk_disable(pc->pwmf->core); > + /* Output is off now, extra release to balance extra acquire */ > + mfpwm_release(pc->pwmf); > + } > + > +err_mfpwm_release: > + mfpwm_release(pc->pwmf); > + > + return ret; > +} > + > Best regards, Damon