From patchwork Wed Sep 8 15:59:01 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: 508191 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=-18.8 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, USER_AGENT_GIT 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 9B184C433FE for ; Wed, 8 Sep 2021 15:59:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6DA1F6113D for ; Wed, 8 Sep 2021 15:59:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349588AbhIHQAa (ORCPT ); Wed, 8 Sep 2021 12:00:30 -0400 Received: from smtp2.axis.com ([195.60.68.18]:28843 "EHLO smtp2.axis.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349777AbhIHQAa (ORCPT ); Wed, 8 Sep 2021 12:00:30 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axis.com; q=dns/txt; s=axis-central1; t=1631116762; x=1662652762; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=RTifGVBj822KoyMzdn4P9gOiPZ0rHHcWYpCtF9e30Kg=; b=IHiAOUuoe34M70/oNVlm0qrAvldbyLn+0wa+3JACcz8oQxJdlJ+XkEG7 grV9v87HwZLBzO/qwr+elz4AeDxtbTkDvps+wFKdiDRE9yiC1Yu8HLc/h 4evHCTRIU0HOJQyodV2SogYMtY8GuayBtSAEjjB9taWyuQyeUsIDetmxq CZd0AxXh4ejpPHQ5xa5NOqx6nPby3oDLeWtbsPFm+CufdycC0+uwP+yCq iICnDEjXmJLTh2aXLOi0XvobTC42l9UQYSvAH+PIdQG94JsOLoeIh1lru WnuNQmesTL9zK2qUGx2bZXKTXlXlrl6+YSxunknmJPzcMZpvFTlShJCcD 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 v2] pwm: pwm-samsung: Trigger manual update when disabling PWM Date: Wed, 8 Sep 2021 17:59:01 +0200 Message-ID: <20210908155901.18944-1-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 --- v2: - Move fix above setting of disabled_mask drivers/pwm/pwm-samsung.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/drivers/pwm/pwm-samsung.c b/drivers/pwm/pwm-samsung.c index f6c528f02d43..53edc0da3ff8 100644 --- a/drivers/pwm/pwm-samsung.c +++ b/drivers/pwm/pwm-samsung.c @@ -105,6 +105,9 @@ struct samsung_pwm_chip { static DEFINE_SPINLOCK(samsung_pwm_lock); #endif +static void __pwm_samsung_manual_update(struct samsung_pwm_chip *chip, + struct pwm_device *pwm); + static inline struct samsung_pwm_chip *to_samsung_pwm_chip(struct pwm_chip *chip) { @@ -276,19 +279,23 @@ 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); } -static void pwm_samsung_manual_update(struct samsung_pwm_chip *chip, +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); @@ -296,6 +303,16 @@ static void pwm_samsung_manual_update(struct samsung_pwm_chip *chip, tcon &= ~TCON_MANUALUPDATE(tcon_chan); writel(tcon, chip->base + REG_TCON); +} + +static void pwm_samsung_manual_update(struct samsung_pwm_chip *chip, + struct pwm_device *pwm) +{ + unsigned long flags; + + spin_lock_irqsave(&samsung_pwm_lock, flags); + + __pwm_samsung_manual_update(chip, pwm); spin_unlock_irqrestore(&samsung_pwm_lock, flags); }