From mboxrd@z Thu Jan 1 00:00:00 1970 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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 7E02DC433B4 for ; Fri, 30 Apr 2021 15:10:28 +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 2C149613C1 for ; Fri, 30 Apr 2021 15:10:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2C149613C1 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 8F2E56F551; Fri, 30 Apr 2021 15:10:27 +0000 (UTC) Received: from m43-7.mailgun.net (m43-7.mailgun.net [69.72.43.7]) by gabe.freedesktop.org (Postfix) with ESMTPS id 801546F551 for ; Fri, 30 Apr 2021 15:10:23 +0000 (UTC) DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1619795426; h=Message-ID: References: In-Reply-To: Subject: Cc: To: From: Date: Content-Transfer-Encoding: Content-Type: MIME-Version: Sender; bh=+dVI3NdaeABnN/N1/ZkuDIQzB1RFAa3KmXh7BK9pWbs=; b=DcAupB4elIxysnksPVg2UYl0RxcZgVhhkrQ+tIGB/wsLSxueTQPBYuFYI8EttzKcLxXQEDzt UT1aMFB2P9/Tm4q1QjYnYYCzWcmShDstm1KMTB9hzSiZyP9iqMCJn69k6kMA3Xn4rqbjC7f2 UXnASzFGKYS6ZuXghPmcFhUdmDQ= X-Mailgun-Sending-Ip: 69.72.43.7 X-Mailgun-Sid: WyJkOTU5ZSIsICJkcmktZGV2ZWxAbGlzdHMuZnJlZWRlc2t0b3Aub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n03.prod.us-west-2.postgun.com with SMTP id 608c1dd9e0e9c9a6b69b8ff1 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Fri, 30 Apr 2021 15:10:17 GMT Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 501D1C43460; Fri, 30 Apr 2021 15:10:17 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: rajeevny) by smtp.codeaurora.org (Postfix) with ESMTPSA id 90E85C433D3; Fri, 30 Apr 2021 15:10:15 +0000 (UTC) MIME-Version: 1.0 Date: Fri, 30 Apr 2021 20:40:15 +0530 From: rajeevny@codeaurora.org To: Doug Anderson , Rob Herring Subject: Re: [v3 1/2] dt-bindings: backlight: add DisplayPort aux backlight In-Reply-To: References: <1619416756-3533-1-git-send-email-rajeevny@codeaurora.org> <1619416756-3533-2-git-send-email-rajeevny@codeaurora.org> <20210429180435.GA1385465@robh.at.kernel.org> Message-ID: <78c4bd291bd4a17ae2a1d02d0217de43@codeaurora.org> X-Sender: rajeevny@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , mkrishn@codeaurora.org, linux-arm-msm , LKML , dri-devel , Sean Paul , Abhinav Kumar , Kalyan Thota , "Kristian H. Kristensen" , freedreno , "Lankhorst, Maarten" Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 30-04-2021 02:33, Doug Anderson wrote: > Hi, > > On Thu, Apr 29, 2021 at 11:04 AM Rob Herring wrote: >> >> On Mon, Apr 26, 2021 at 11:29:15AM +0530, Rajeev Nandan wrote: >> > Add bindings for DisplayPort aux backlight driver. >> > >> > Changes in v2: >> > - New >> > >> > Signed-off-by: Rajeev Nandan >> > --- >> > .../bindings/leds/backlight/dp-aux-backlight.yaml | 49 ++++++++++++++++++++++ >> > 1 file changed, 49 insertions(+) >> > create mode 100644 Documentation/devicetree/bindings/leds/backlight/dp-aux-backlight.yaml >> > >> > diff --git a/Documentation/devicetree/bindings/leds/backlight/dp-aux-backlight.yaml b/Documentation/devicetree/bindings/leds/backlight/dp-aux-backlight.yaml >> > new file mode 100644 >> > index 00000000..0fa8bf0 >> > --- /dev/null >> > +++ b/Documentation/devicetree/bindings/leds/backlight/dp-aux-backlight.yaml >> > @@ -0,0 +1,49 @@ >> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) >> > +%YAML 1.2 >> > +--- >> > +$id: http://devicetree.org/schemas/leds/backlight/dp-aux-backlight.yaml# >> > +$schema: http://devicetree.org/meta-schemas/core.yaml# >> > + >> > +title: DisplayPort aux backlight driver bindings >> > + >> > +maintainers: >> > + - Rajeev Nandan >> > + >> > +description: >> > + Backlight driver to control the brightness over DisplayPort aux channel. >> > + >> > +allOf: >> > + - $ref: common.yaml# >> > + >> > +properties: >> > + compatible: >> > + const: dp-aux-backlight >> > + >> > + ddc-i2c-bus: >> > + $ref: /schemas/types.yaml#/definitions/phandle >> > + description: >> > + A phandle to the system I2C controller connected to the DDC bus used >> > + for the DisplayPort AUX channel. >> > + >> > + enable-gpios: >> > + maxItems: 1 >> > + description: GPIO specifier for backlight enable pin. >> > + >> > + max-brightness: true >> > + >> > +required: >> > + - compatible >> > + - ddc-i2c-bus >> > + >> > +additionalProperties: false >> > + >> > +examples: >> > + - | >> > + backlight { >> > + compatible = "dp-aux-backlight"; >> > + ddc-i2c-bus = <&sn65dsi86_bridge>; >> > + enable-gpios = <&tlmm 12 GPIO_ACTIVE_HIGH>; >> >> So the DDC bus is connected to a backlight and also a panel? This >> binding is not reflecting the h/w, but rather what you want for some >> driver. >> >> There's only one thing here and that's an eDP panel which supports >> backlight control via DP aux channel. You can figure all that out from >> the panel's compatible and/or reading the EDID. >> >> You might also be interested in this thread: >> >> https://lore.kernel.org/lkml/YIKsDtjcIHGNvW0u@orome.fritz.box/ > > I think Rajeev needs to rework everything anyway as per: > > https://lore.kernel.org/r/87zgxl5qar.fsf@intel.com > > ...but you're right that it makes sense not to model the backlight as > a separate node in the device tree. The panel driver can handle > setting up the backlight. > > -Doug It was not a good idea to create a separate backlight driver and use ddc-i2c-bus to get access to DP aux. I am working to move the code to the panel driver and to utilize the new DRM helper functions (drm_edp_backlight_*) Lyude has added [1]. To use these helper functions, the panel driver should have access to the "struct drm_dp_aux *". The simple-panel has a "ddc-i2c-bus" property to give the panel access to the DDC bus and is currently being used to get the EDID from the panel. Can I use the same ddc bus i2c_adapter to get the "struct drm_dp_aux *"? As per the suggestion [2], I get the "struct drm_dp_aux *" from the i2c_adapter of ddc bus (maybe I didn't understand the suggestion correctly), and, it turned out, the way I have implemented is not the right way [3]. So, I am afraid to use the same method in the panel driver. [1] https://lore.kernel.org/dri-devel/871rb5bcf9.fsf@intel.com/ [2] https://www.spinics.net/lists/dri-devel/msg295429.html [3] https://lore.kernel.org/dri-devel/20210426111116.4lc3ekxjugjr3oho@maple.lan/ Thanks, Rajeev _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel