From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S933249AbdJQIOs (ORCPT <rfc822;w@1wt.eu>);
        Tue, 17 Oct 2017 04:14:48 -0400
Received: from regular1.263xmail.com ([211.150.99.136]:54864 "EHLO
        regular1.263xmail.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1758019AbdJQIOJ (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 17 Oct 2017 04:14:09 -0400
X-263anti-spam: KSV:0;BIG:0;
X-MAIL-GRAY: 0
X-MAIL-DELIVERY: 1
X-KSVirus-check: 0
X-ADDR-CHECKED4: 1
X-ABS-CHECKED: 1
X-SKE-CHECKED: 1
X-ANTISPAM-LEVEL: 2
X-RL-SENDER: jeffy.chen@rock-chips.com
X-FST-TO: briannorris@chromium.org
X-SENDER-IP: 103.29.142.67
X-LOGIN-NAME: jeffy.chen@rock-chips.com
X-UNIQUE-TAG: <8d120dd82444e6c4cd4df057cde7e51e>
X-ATTACHMENT-NUM: 0
X-DNS-TYPE: 0
Message-ID: <59E5BBC3.2020504@rock-chips.com>
Date: Tue, 17 Oct 2017 16:13:55 +0800
From: jeffy <jeffy.chen@rock-chips.com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:19.0) Gecko/20130126 Thunderbird/19.0
MIME-Version: 1.0
To: Brian Norris <briannorris@chromium.org>
CC: linux-kernel@vger.kernel.org, dmitry.torokhov@gmail.com,
        heiko@sntech.de, rjw@rjwysocki.net, dianders@chromium.org,
        tfiga@chromium.org, broonie@kernel.org, seanpaul@chromium.org,
        linux-pwm@vger.kernel.org, linux-fbdev@vger.kernel.org,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Thierry Reding <thierry.reding@gmail.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        dri-devel@lists.freedesktop.org, Jingoo Han <jingoohan1@gmail.com>,
        Lee Jones <lee.jones@linaro.org>
Subject: Re: [RESEND PATCH v2 2/5] backlight: pwm_bl: Add device link for
 pwm_bl and pwm
References: <20171016100640.26575-1-jeffy.chen@rock-chips.com> <20171016100640.26575-3-jeffy.chen@rock-chips.com> <20171016235710.GA12188@google.com>
In-Reply-To: <20171016235710.GA12188@google.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Hi Brian,

On 10/17/2017 07:57 AM, Brian Norris wrote:
> This is going to be a*lot*  of churn throughout the tree, if we expect
> all resource consumers to do this. I think we'd want some kind of
> agreement from the PM maintainers and (larger) subsystem owners before
> going down this route...
>
> And in the PWM case, pwm_get() already has the device pointer. Why can't
> we just instrument it instead?

according to pwm_bl driver, we may need to take care of pwm_request() too:

         pb->pwm = devm_pwm_get(&pdev->dev, NULL);
         if (IS_ERR(pb->pwm) && PTR_ERR(pb->pwm) != -EPROBE_DEFER && 
!node) {
                 dev_err(&pdev->dev, "unable to request PWM, trying 
legacy API\n");
                 pb->legacy = true;
                 pb->pwm = pwm_request(data->pwm_id, "pwm-backlight");
         }

and maybe also *of_pwm_get...

maybe we can add a dummy pwm chip for those orphan pwms?
>
> Brian