From patchwork Sat Jun 20 12:17:51 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hans de Goede X-Patchwork-Id: 11615909 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 196EB138C for ; Sat, 20 Jun 2020 12:19:13 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id ECA9823B6A for ; Sat, 20 Jun 2020 12:19:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="W95XpneO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ECA9823B6A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id D09826E297; Sat, 20 Jun 2020 12:19:11 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [207.211.31.120]) by gabe.freedesktop.org (Postfix) with ESMTPS id 775556E296 for ; Sat, 20 Jun 2020 12:19:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1592655547; 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=EMbMxst1oiHtTJmDDNK1CEbufosoaisjf4HJnYds+98=; b=W95XpneOWRr4DXOT0eyE8+nEI+jpkxdVi+HbClEp/T3C3AEP6AfQRkuFBTMXo+WX+uFjmy rv2SCEjvO8kqMEt66ZQSGxcE8EFpk8SbbpSMdyxl/dVLJ8oSotm3rjnhatakJl8Qeseh4I Lfj3noxizss4b0coAynoN4hXcfQO5qk= 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-441-Rf05V75sPlWeqdDi3sMHxw-1; Sat, 20 Jun 2020 08:19:03 -0400 X-MC-Unique: Rf05V75sPlWeqdDi3sMHxw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7499618B5F8E; Sat, 20 Jun 2020 12:19:01 +0000 (UTC) Received: from x1.localdomain.com (ovpn-112-42.ams2.redhat.com [10.36.112.42]) by smtp.corp.redhat.com (Postfix) with ESMTP id ED6D710021B3; Sat, 20 Jun 2020 12:18:58 +0000 (UTC) From: Hans de Goede To: Thierry Reding , =?utf-8?q?Uwe_Kleine-K=C3=B6n?= =?utf-8?q?ig?= , Jani Nikula , Joonas Lahtinen , =?utf-8?b?VmlsbGUgU3ly?= =?utf-8?b?asOkbMOk?= , "Rafael J . Wysocki" , Len Brown Date: Sat, 20 Jun 2020 14:17:51 +0200 Message-Id: <20200620121758.14836-9-hdegoede@redhat.com> In-Reply-To: <20200620121758.14836-1-hdegoede@redhat.com> References: <20200620121758.14836-1-hdegoede@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Subject: [Intel-gfx] [PATCH v3 08/15] pwm: crc: Fix period changes not having any effect X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-pwm@vger.kernel.org, linux-acpi@vger.kernel.org, intel-gfx , dri-devel@lists.freedesktop.org, Andy Shevchenko , Mika Westerberg Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" 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 I strongly suspect that the BACKLIGHT_EN register at address 0x51 really controls a separate output-only GPIO which is connected to the LCD panels backlight-enable input. Like how the PANEL_EN register at address 0x52 controls an output-only GPIO which is earmarked for the LCD panel's enable pin. If this is correct then this GPIO should really be added to the gpio-crystalcove.c driver and the PWM driver should stop poking it. But I've been unable to come up with a definitive answer here, so I'm keeping this as is for now. 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. 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 */