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 X-Spam-Level: X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 EDD52C433E8 for ; Tue, 25 Aug 2020 10:01:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CDC7F2075B for ; Tue, 25 Aug 2020 10:01:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="NOgnapr6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729723AbgHYKBy (ORCPT ); Tue, 25 Aug 2020 06:01:54 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:48134 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729773AbgHYKBv (ORCPT ); Tue, 25 Aug 2020 06:01:51 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1598349710; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=X/u2P3rm/Mt8sbxumEdSG8Sz04qHhuY60Fsw4/vcSuw=; b=NOgnapr6sfugwbGOvXV++8R5l3/kYuZ9iBireMe/qmAYHubBBkdpAxpqh4P4F7Lg4lTX7L 8th6RtYzb20UgjjzSPc+6wvru0PQi2OxwVfF8pxyCE52K662wLIQ4Y+AoS78P3BhRHHh9w XCWBr5WUPm3tZQRz2duafawc63MX0tw= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-512-gxVR9kmzMxGaeUrsftU7VA-1; Tue, 25 Aug 2020 06:01:48 -0400 X-MC-Unique: gxVR9kmzMxGaeUrsftU7VA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 919FA56BE6; Tue, 25 Aug 2020 10:01:46 +0000 (UTC) Received: from x1.localdomain.com (ovpn-114-132.ams2.redhat.com [10.36.114.132]) by smtp.corp.redhat.com (Postfix) with ESMTP id D377280DE9; Tue, 25 Aug 2020 10:01:43 +0000 (UTC) From: Hans de Goede To: Thierry Reding , =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , "Rafael J . Wysocki" , Len Brown Cc: Hans de Goede , linux-pwm@vger.kernel.org, intel-gfx , dri-devel@lists.freedesktop.org, Andy Shevchenko , Mika Westerberg , linux-acpi@vger.kernel.org Subject: [PATCH v7 09/16] pwm: crc: Fix period changes not having any effect Date: Tue, 25 Aug 2020 12:00:59 +0200 Message-Id: <20200825100106.61941-10-hdegoede@redhat.com> In-Reply-To: <20200825100106.61941-1-hdegoede@redhat.com> References: <20200825100106.61941-1-hdegoede@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org The pwm-crc code is using 2 different enable bits: 1. bit 7 of the PWM0_CLK_DIV (PWM_OUTPUT_ENABLE) 2. bit 0 of the BACKLIGHT_EN register The BACKLIGHT_EN register at address 0x51 really controls a separate output-only GPIO which is earmarked to be used as output connected to the backlight-enable pin for LCD panels, this GPO is part of the PMIC's "Display Panel Control Block." . This pin should probably be moved over to a GPIO provider driver (and consumers modified accordingly), but that is something for an(other) patch. Enabling / disabling the actual PWM output is controlled by the PWM_OUTPUT_ENABLE bit of the PWM0_CLK_DIV register. As the comment in the old code already indicates we must disable the PWM before we can change the clock divider. But the crc_pwm_disable() and crc_pwm_enable() calls the old code make for this only change the BACKLIGHT_EN register; and the value of that register does not matter for changing the period / the divider. What does matter is that the PWM_OUTPUT_ENABLE bit must be cleared before a new value can be written. This commit modifies crc_pwm_config() to clear PWM_OUTPUT_ENABLE instead when changing the period, so that period changes actually work. Note this fix will cause a significant behavior change on some devices using the CRC PWM output to drive their backlight. Before the PWM would always run with the output frequency configured by the BIOS at boot, now the period time specified by the i915 driver will actually be honored. Reviewed-by: Andy Shevchenko Signed-off-by: Hans de Goede --- drivers/pwm/pwm-crc.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/drivers/pwm/pwm-crc.c b/drivers/pwm/pwm-crc.c index 44ec7d5b63e1..81232da0c767 100644 --- a/drivers/pwm/pwm-crc.c +++ b/drivers/pwm/pwm-crc.c @@ -82,14 +82,11 @@ static int crc_pwm_config(struct pwm_chip *c, struct pwm_device *pwm, if (pwm_get_period(pwm) != period_ns) { int clk_div = crc_pwm_calc_clk_div(period_ns); - /* changing the clk divisor, need to disable fisrt */ - crc_pwm_disable(c, pwm); + /* changing the clk divisor, clear PWM_OUTPUT_ENABLE first */ + regmap_write(crc_pwm->regmap, PWM0_CLK_DIV, 0); regmap_write(crc_pwm->regmap, PWM0_CLK_DIV, clk_div | PWM_OUTPUT_ENABLE); - - /* enable back */ - crc_pwm_enable(c, pwm); } /* change the pwm duty cycle */ -- 2.28.0