From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1525081921; cv=none; d=google.com; s=arc-20160816; b=Yl5L6zj662Lc9qXIhHXK1CUE4hiu+M544OQNwNee1EBRorAAyKbbTosXLKgjGtOb2u B3rhYUn/UAVwcLJrdTdsppaDFono/NsDslbA/xG1lG7t2j2J3r8TslOy/zfxK6747oMP Ve6qM5XtB/7WeBKej2RE3ncPMekuC4FJloi6xxV8VVh3s2cCr7fWmKULEoa/zecRr44D GBgUOyRPQNAI0/zWqI+bOZDyJcGMf1We9NWtVzX6Y3kjCdFSjhQF/8xGoScm7QViZimd 3EdtfYyKL8a5eSmUGt9/49T7HwyblAHF1yoaWWgugqAnqYYgec6sE5l13kFTm87FLXDp 3XLQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:dkim-signature :arc-authentication-results; bh=wT74rgCsD1mNwP5LYNX6hwgUMiGnfTDE1Mk9TZ12klM=; b=NMoq/eS0zdPQhUbioiD0nLfsZjgbF5UrNMKPhJwwCugsCxE3oHxcgGanZtqsgLCVCT 57V6YGorKr6JGXLGo2R0zl8422XxYs/5Ii8HpmtQ481ecJL8IDqulGI662K9X3aciWuZ zqONmNCJBMThC4c2d+8NlZfWUDc+kGHiERoB7NhbCeXVLyNZCLvXX/SjTujmUetsZfpY Uao31c61Ni+Ry2UVY7TBpLvzfVklLZ+ATFluy2S2TbqmBst+f8k1DDzXAGTj1+fX213B EucwB2XnduLIH1VsIkvGWeGsOxhQbtTCVjx9PSsp35Ys1ronPwin+AomdPK6MeJfjzVT D3Xg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=GsLv83/W; spf=pass (google.com: domain of thierry.reding@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=thierry.reding@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=GsLv83/W; spf=pass (google.com: domain of thierry.reding@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=thierry.reding@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com X-Google-Smtp-Source: AB8JxZqjkRatoThS6f8A7TvuGDJlcDG9CSgN+lURYRBO4Kg+67ZVdy+zeVvXa5loHgKNyXq5rTDaMw== Date: Mon, 30 Apr 2018 11:51:59 +0200 From: Thierry Reding To: Rajkumar Rampelli Cc: robh+dt@kernel.org, mark.rutland@arm.com, jonathanh@nvidia.com, jdelvare@suse.com, linux@roeck-us.net, corbet@lwn.net, catalin.marinas@arm.com, will.deacon@arm.com, kstewart@linuxfoundation.org, gregkh@linuxfoundation.org, pombredanne@nexb.com, mmaddireddy@nvidia.com, mperttunen@nvidia.com, arnd@arndb.de, timur@codeaurora.org, andy.gross@linaro.org, xuwei5@hisilicon.com, elder@linaro.org, heiko@sntech.de, krzk@kernel.org, ard.biesheuvel@linaro.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pwm@vger.kernel.org, linux-tegra@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-doc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, ldewangan@nvidia.com Subject: Re: [PATCH V2 1/9] pwm: core: Add support for PWM HW driver with pwm capture only Message-ID: <20180430095159.GD2476@ulmo> References: <1521607244-29734-1-git-send-email-rrajk@nvidia.com> <1521607244-29734-2-git-send-email-rrajk@nvidia.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="+B+y8wtTXqdUj1xM" Content-Disposition: inline In-Reply-To: <1521607244-29734-2-git-send-email-rrajk@nvidia.com> User-Agent: Mutt/1.9.5 (2018-04-13) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1595520845385709681?= X-GMAIL-MSGID: =?utf-8?q?1599164301290484067?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: --+B+y8wtTXqdUj1xM Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Mar 21, 2018 at 10:10:36AM +0530, Rajkumar Rampelli wrote: > Add support for pwm HW driver which has only capture functionality. > This helps to implement the PWM based Tachometer driver which reads > the PWM output signals from electronic fans. >=20 > PWM Tachometer captures the period and duty cycle of the PWM signal >=20 > Add conditional checks for callabacks enable(), disable(), config() > to check if they are supported by the client driver or not. Skip these > callbacks if they are not supported. >=20 > Signed-off-by: Rajkumar Rampelli > --- >=20 > V2: Added if conditional checks for pwm callbacks since drivers may > implements only pwm capture functionality. >=20 > drivers/pwm/core.c | 21 +++++++++++++++------ > 1 file changed, 15 insertions(+), 6 deletions(-) >=20 > diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c > index 1581f6a..f70fe68 100644 > --- a/drivers/pwm/core.c > +++ b/drivers/pwm/core.c > @@ -246,6 +246,10 @@ static bool pwm_ops_check(const struct pwm_ops *ops) > if (ops->apply) > return true; > =20 > + /* driver supports capture operation */ > + if (ops->capture) > + return true; > + > return false; > } > =20 > @@ -495,7 +499,8 @@ int pwm_apply_state(struct pwm_device *pwm, struct pw= m_state *state) > * ->apply(). > */ > if (pwm->state.enabled) { > - pwm->chip->ops->disable(pwm->chip, pwm); > + if (pwm->chip->ops->disable) > + pwm->chip->ops->disable(pwm->chip, pwm); This is not a good idea. It means that you'll be able to successfully configure a capture-only PWM channel for output. I think all of the output configuration functions should return an error (-ENOSYS?) for capture-only devices, much like we return -ENOSYS for pwm_capture() if the driver doesn't implement capture support. 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