From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from cstnet.cn (smtp21.cstnet.cn [159.226.251.21]) (using TLSv1.2 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4709C344DA4; Thu, 11 Jun 2026 05:43:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=159.226.251.21 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781156623; cv=none; b=nqupLrLplYmByU9Ir+p90lWwNu6LCOtTeEcAUpXwyEt26TJZrb1B8IOcX9pAXOM7989DPdHwrzyWPiTStpm2x4mFqeQgXW3dOC2bMN5VZz8lS2Rs1JmyBfgU8qUx/9DylaK0YtcHhfgqzZRFrjdCIuWziBKEgj+eHKZ1oHJf9+A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781156623; c=relaxed/simple; bh=CEsXtE7RJUsN+rxk0Lx/Pi6v19bnjVmLwkhNSAJhWWM=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=hsE8oCDyAFTp6/aLEddNH7Y9i0yqwcwhIiD7XxX/t1aymsrf4hBdOWPiK6owPb5DS0QvF+j9V4m9/ykE8cqMsdJ22SZ8iznXVIzd4zXYaJPM8v/mgjoc6d/SGhvmOv+Y/61Nb9ErnHEB40HZVb7wt6hPeBZGjwZUe5dMmc9bi0E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn; spf=pass smtp.mailfrom=iscas.ac.cn; arc=none smtp.client-ip=159.226.251.21 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iscas.ac.cn Received: from edelgard.fodlan.icenowy.me (unknown [112.94.100.167]) by APP-01 (Coremail) with SMTP id qwCowACXOtMBSypqL+NEAQ--.1358S2; Thu, 11 Jun 2026 13:43:30 +0800 (CST) Message-ID: <69a18fd1a1b9f375bbccfbe0d9e88ab31a01a188.camel@iscas.ac.cn> Subject: Re: [PATCH 3/3] drm/panel: himax-hx83121a: add backlight regulator support From: Icenowy Zheng To: Pengyu Luo Cc: Neil Armstrong , Jessica Zhang , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Liam Girdwood , Mark Brown , dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Date: Thu, 11 Jun 2026 13:43:29 +0800 In-Reply-To: <178115560757.199930.5802398831559617564.b4-review@b4> References: <20260608162622.403713-1-zhengxingda@iscas.ac.cn> <20260608162622.403713-3-zhengxingda@iscas.ac.cn> <178115560757.199930.5802398831559617564.b4-review@b4> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.3 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID:qwCowACXOtMBSypqL+NEAQ--.1358S2 X-Coremail-Antispam: 1UD129KBjvdXoWrtF1fGryxZF1rJFyUKrWUCFg_yoWkZwc_Wr 4jqrZFqrWqqr4kCFn7AFyftF93KFs5uFn7Z3ZYy34aka47CrsrZrWUXrWrAas8Jw1FkFyq kanrZFyFvr4DWjkaLaAFLSUrUUUUjb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUIcSsGvfJTRUUUbskYjsxI4VW3JwAYFVCjjxCrM7AC8VAFwI0_Gr0_Xr1l1xkIjI8I 6I8E6xAIw20EY4v20xvaj40_Wr0E3s1l1IIY67AEw4v_Jr0_Jr4l8cAvFVAK0II2c7xJM2 8CjxkF64kEwVA0rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVW5JVW7JwA2z4x0Y4vE2Ix0 cI8IcVCY1x0267AKxVWxJVW8Jr1l84ACjcxK6I8E87Iv67AKxVWxJr0_GcWl84ACjcxK6I 8E87Iv6xkF7I0E14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI 64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r106r15McIj6I8E87Iv67AKxVWUJVW8Jw Am72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IY64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1l c7CjxVAaw2AFwI0_Jw0_GFyl42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr 1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE 14v26r4a6rW5MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7 IYx2IY6xkF7I0E14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E 87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73Uj IFyTuYvjxU7veHUUUUU X-CM-SenderInfo: x2kh0wp0lqwv3d6l2u1dvotugofq/ =E5=9C=A8 2026-06-11=E5=9B=9B=E7=9A=84 13:26 +0800=EF=BC=8CPengyu Luo=E5=86= =99=E9=81=93=EF=BC=9A > On Tue, 09 Jun 2026 00:26:22 +0800, Icenowy Zheng > wrote: > > diff --git a/drivers/gpu/drm/panel/panel-himax-hx83121a.c > > b/drivers/gpu/drm/panel/panel-himax-hx83121a.c > > index 1a7e0125bced..e31e2fba0a78 100644 > > --- a/drivers/gpu/drm/panel/panel-himax-hx83121a.c > > +++ b/drivers/gpu/drm/panel/panel-himax-hx83121a.c > > @@ -195,7 +197,27 @@ static int himax_bl_update_status(struct > > backlight_device *bl) > > [ ... skip 18 lines ... ] > > + ret =3D regulator_enable(ctx->bl_supply); > > + if (ret) > > + return ret; > > + > > + ctx->backlight_enabled =3D true; > > + >=20 > If you use a pin, (it is indeed a hwen pin as we know) you can > simplify it like this, >=20 > bool bl_enable_now =3D !!brightness; >=20 > if (ctx->bl_enable !=3D bl_enable_now) { > gpiod_set_value(ctx->hwen_gpio, bl_enable_now); > ctx->bl_enable =3D bl_enable_now; > } >=20 > BTW, iirc, panel bias can be turned off too, although I don't think > this will save too much power. BTW during my test, it seems that DCS backlight 0 isn't turning off backlight. Thanks, Icenowy >=20 > Best wishes, > Pengyu