From patchwork Thu Sep 9 10:10:42 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?M=C3=A5rten_Lindahl?= X-Patchwork-Id: 508637 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=-18.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 0C656C433EF for ; Thu, 9 Sep 2021 10:10:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E6E1B611C2 for ; Thu, 9 Sep 2021 10:10:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233563AbhIIKL6 (ORCPT ); Thu, 9 Sep 2021 06:11:58 -0400 Received: from smtp2.axis.com ([195.60.68.18]:54458 "EHLO smtp2.axis.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229995AbhIIKL6 (ORCPT ); Thu, 9 Sep 2021 06:11:58 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axis.com; q=dns/txt; s=axis-central1; t=1631182249; x=1662718249; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=8WA791u9a+qKUngkNVzY5nIzKD8RRpENC0AG6NpLung=; b=N7dXfY2CxoMInJmyiYFVAsSftNCrVD8UfRAiWuKcWJZdzrG8OTNnFsIR +RIKAse6ctCouCBl4smzWSeEu7fvIJoMR59G2qsehkUZ5Qe3H/SyycvMN bEta1dSzckDyPodZ5UqFaX5H9de1gOCK1cR99dNq+6H4MGCUPaDiyIHAD ikfawhROqqu3D9+arFzXN8MCgY0beDf2ngIpBoxw2fBXtbm+13R051IDk jVzL477KtBAX/w0zi7i/czZlzfYOFUZUl9hJofHg1Xo2yD8m05eAd5BK1 drmIfqzhYplwCThHDLXegFWnVPH6tULoVVzckESDHG2Tka/WdS3Jlj2Zr Q==; From: =?utf-8?q?M=C3=A5rten_Lindahl?= To: Krzysztof Kozlowski , Thierry Reding , Lee Jones CC: =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= , , , , , =?utf-8?q?M=C3=A5rten_Lindahl?= Subject: [PATCH v3] pwm: pwm-samsung: Trigger manual update when disabling PWM Date: Thu, 9 Sep 2021 12:10:42 +0200 Message-ID: <20210909101042.17431-1-marten.lindahl@axis.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-samsung-soc@vger.kernel.org When duty-cycle is at full level (100%), the TCNTn and TCMPn registers needs to be flushed in order to disable the signal. The PWM manual does not say anything about this, but states that only clearing the TCON auto-reload bit should be needed, and this seems to be true when the PWM duty-cycle is not at full level. This can be observed on an Axis ARTPEC-8, by running: echo > pwm/period echo > pwm/duty_cycle echo 1 > pwm/enable echo 0 > pwm/enable Since the TCNTn and TCMPn registers are activated when enabling the PWM (setting TCON auto-reload bit), and are not touched when disabling the PWM, the double buffered auto-reload function seems to be still active. Lowering duty-cycle, and restoring it again in between the enabling and disabling, makes the disable work since it triggers a reload of the TCNTn and TCMPn registers. Fix this by securing a reload of the TCNTn and TCMPn registers when disabling the PWM and having a full duty-cycle. Signed-off-by: Mårten Lindahl Reviewed-by: Krzysztof Kozlowski --- v2: - Move fix above setting of disabled_mask v3: - Move up definition of __pwm_samsung_manual_update to avoid declaration of the same drivers/pwm/pwm-samsung.c | 30 ++++++++++++++++++++++-------- 1 file changed, 22 insertions(+), 8 deletions(-) diff --git a/drivers/pwm/pwm-samsung.c b/drivers/pwm/pwm-samsung.c index f6c528f02d43..f660ec2501fd 100644 --- a/drivers/pwm/pwm-samsung.c +++ b/drivers/pwm/pwm-samsung.c @@ -117,6 +117,20 @@ static inline unsigned int to_tcon_channel(unsigned int channel) return (channel == 0) ? 0 : (channel + 1); } +static void __pwm_samsung_manual_update(struct samsung_pwm_chip *chip, + struct pwm_device *pwm) +{ + unsigned int tcon_chan = to_tcon_channel(pwm->hwpwm); + u32 tcon; + + tcon = readl(chip->base + REG_TCON); + tcon |= TCON_MANUALUPDATE(tcon_chan); + writel(tcon, chip->base + REG_TCON); + + tcon &= ~TCON_MANUALUPDATE(tcon_chan); + writel(tcon, chip->base + REG_TCON); +} + static void pwm_samsung_set_divisor(struct samsung_pwm_chip *pwm, unsigned int channel, u8 divisor) { @@ -276,6 +290,13 @@ static void pwm_samsung_disable(struct pwm_chip *chip, struct pwm_device *pwm) tcon &= ~TCON_AUTORELOAD(tcon_chan); writel(tcon, our_chip->base + REG_TCON); + /* + * In case the PWM is at 100% duty cycle, force a manual + * update to prevent the signal from staying high. + */ + if (readl(our_chip->base + REG_TCMPB(pwm->hwpwm)) == (u32)-1U) + __pwm_samsung_manual_update(our_chip, pwm); + our_chip->disabled_mask |= BIT(pwm->hwpwm); spin_unlock_irqrestore(&samsung_pwm_lock, flags); @@ -284,18 +305,11 @@ static void pwm_samsung_disable(struct pwm_chip *chip, struct pwm_device *pwm) static void pwm_samsung_manual_update(struct samsung_pwm_chip *chip, struct pwm_device *pwm) { - unsigned int tcon_chan = to_tcon_channel(pwm->hwpwm); - u32 tcon; unsigned long flags; spin_lock_irqsave(&samsung_pwm_lock, flags); - tcon = readl(chip->base + REG_TCON); - tcon |= TCON_MANUALUPDATE(tcon_chan); - writel(tcon, chip->base + REG_TCON); - - tcon &= ~TCON_MANUALUPDATE(tcon_chan); - writel(tcon, chip->base + REG_TCON); + __pwm_samsung_manual_update(chip, pwm); spin_unlock_irqrestore(&samsung_pwm_lock, flags); }