From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=178.238.236.174 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794303291; b=3B2dqSQshF6+emJsTKaeLRi7BFrnSlkz0tOGTw2wDsi9002W7bSaYC3394chPPaBg9tX c1K+tgjTH3/LMO42F9U8rz6ro6xrJyWJJMDYY3MLyHPSbcnAnixVNU7GAiHeY7BOd4uhv 5e/qBII+b4tPopg34g96D36PxedE2VirC/DBXXogmbUnjrCZYRITX/+xI6o+QGfTKpTqm 7fZU6QRaQnLsN0TKXRmSACx0lbMf5qkwkq8VdEuf2Sp2a3Jgiv3hHYqQnDg+SxKxuDVZR aUlMzqm5RQ8iu1MsEMeqSKVV8MUqRjlngCFzvXcL6fToR3E+xdyljkUx1HWX3FkkR6w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794303291; h=DMARC-Filter:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: In-Reply-To:References:X-Mailer:MIME-Version:Content-Type: Content-Transfer-Encoding; bh=5/I/TK2BRl2LnMysxk0s70GG7ZihlSvhoUVTH7m/jhE=; b=thiqQNSUCD+XmvdxTf4Hyd6phmAXMAGjRR/ETSsEtqeVs1js0Hghvg6h2EAuM5Chm6O4 43qPr4aueoDWefNm6rmja3tZpJoVLZv/Je2JeD2de/Vu3YClQcJ49NOiBWWYuRmcCWYdK zf7X787jzRZX3hmBbVdOypWNnPbgvMEdJeDMea3nHNFFg6xV3ET2/Os1gfsKfkFZTc8DV Sf3eeExbNsGn5NDsUXOBzgIZ77CBO9Qf5q8wsCRq6QWofeeJai4XlfEfL67njn7etypKL B+x/ftkBotrrR2Kz13BqCnCDSETCYzHuL7UMaRCzxCHCBuNYWNdTICAfLuSPKB7rmrw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=kemnade.info; spf=pass smtp.mailfrom=kemnade.info; dkim=pass header.d=kemnade.info header.i=@kemnade.info header.a=rsa-sha256 header.s=20220719 header.b=jAsrU0jx; arc=none smtp.remote-ip=178.238.236.174 Received: from mail.andi.de1.cc (mail.andi.de1.cc [178.238.236.174]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6FCA0606C66C; Tue, 10 Nov 2026 09:34:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 6FCA0606C66C Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=kemnade.info Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kemnade.info Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kemnade.info header.i=@kemnade.info header.a=rsa-sha256 header.s=20220719 header.b=jAsrU0jx DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=kemnade.info; s=20220719; h=References:In-Reply-To:Subject:Cc:To:From: Reply-To:Content-ID:Content-Description; bh=5/I/TK2BRl2LnMysxk0s70GG7ZihlSvhoUVTH7m/jhE=; t=1794303290; x=1795512890; b=jAsrU0jxdT4bhi/7kOnKpXwLM2lKEBnWxAgbxAMqAtOai2IzRK+iFuKWUSqXJ8tp9Ddl2joSYt0 gz0xJdCt+YP7zAGoWTs12zApfKVGLGA9UPX/KiJSc8890Px/DAXYfhCx2d5EN3AIT++/s0WIu2BRz awH74//H7JMUWGsL8P3Eht6ijOJXzeWpEho8sN5K0sCemmKXGNprrCTKfrHKnlsFDeP3/KZ9FWchs et/IGUjG/8apqXfHT0DROwxc/3y7oqtPQAFGtR/5PeMWY/wxpioZhDpv1v/ssDWvT90QO5lZ7CMg4 XlF+NYRs+AD5FXGOha9XdV5sKc31R+4VNIyg==; Date: Tue, 10 Nov 2026 10:34:05 +0100 From: Andreas Kemnade To: Alistair Cc: Pablo Mazzini , Frank Li , Sascha Hauer , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Pengutronix Kernel Team , Fabio Estevam , devicetree@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/7] ARM: dts: imx: keep the SY7636A VCOM on Message-ID: <20261110103405.5e0384bb@kemnade.info> In-Reply-To: <54130686e08db48928484e226f48dc31a8c5ee29.camel@alistair23.me> References: <20261026003918.155321-1-pmazzini@gmail.com> <20261026003918.155321-2-pmazzini@gmail.com> <20261026083058.04173f10@kemnade.info> <54130686e08db48928484e226f48dc31a8c5ee29.camel@alistair23.me> X-Mailer: Claws Mail 4.3.1 (GTK 3.24.49; aarch64-unknown-linux-gnu) X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Tue, 10 Nov 2026 15:23:03 +1000 Alistair wrote: > On Mon, 2026-10-26 at 08:30 +0100, Andreas Kemnade wrote: > > On Mon, 26 Oct 2026 00:39:12 +0000 > > Pablo Mazzini wrote: > > =20 > > > The SY7636A hwmon driver turns VCOM on at probe. The reMarkable 2, > > > Kobo > > > Libra H2O and Tolino Vision 5 have had the rails on so far. Mark > > > VCOM > > > always-on before the driver stops doing it. > > >=20 > > > Signed-off-by: Pablo Mazzini > > > --- > > > =C2=A0arch/arm/boot/dts/nxp/imx/e70k02.dtsi=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 | 1 + > > > =C2=A0arch/arm/boot/dts/nxp/imx/imx7d-remarkable2.dts | 1 + > > > =C2=A02 files changed, 2 insertions(+) > > >=20 > > > diff --git a/arch/arm/boot/dts/nxp/imx/e70k02.dtsi > > > b/arch/arm/boot/dts/nxp/imx/e70k02.dtsi > > > index dc7ff108aa85..bd9c6c6fa117 100644 > > > --- a/arch/arm/boot/dts/nxp/imx/e70k02.dtsi > > > +++ b/arch/arm/boot/dts/nxp/imx/e70k02.dtsi > > > @@ -154,6 +154,7 @@ sy7636: pmic@62 { > > > =C2=A0 regulators { > > > =C2=A0 reg_epdpmic: vcom { > > > =C2=A0 regulator-name =3D "vcom"; > > > + regulator-always-on; > > > =C2=A0 }; > > > =C2=A0 }; > > > =C2=A0 }; =20 > > No, please not. That regulator is in practice used with a not yet > > upstreamed > > driver for the EPDC on that platform used to deal with the current > > kernels > > fp9931 / tps65185 drivers. So it is very welcome to have it not > > always turned > > on. > >=20 > > =20 > > > diff --git a/arch/arm/boot/dts/nxp/imx/imx7d-remarkable2.dts > > > b/arch/arm/boot/dts/nxp/imx/imx7d-remarkable2.dts > > > index ff9d50942884..6cf5603c0752 100644 > > > --- a/arch/arm/boot/dts/nxp/imx/imx7d-remarkable2.dts > > > +++ b/arch/arm/boot/dts/nxp/imx/imx7d-remarkable2.dts > > > @@ -327,6 +327,7 @@ sy7636a: pmic@62 { > > > =C2=A0 regulators { > > > =C2=A0 reg_epdpmic: vcom { > > > =C2=A0 regulator-name =3D "vcom"; > > > + regulator-always-on; > > > =C2=A0 regulator-boot-on; > > > =C2=A0 }; > > > =C2=A0 }; =20 > >=20 > >=20 > > Here the situation is a bit different. If I remember correctly, there > > is some special EPD logic in userspace on top of some ordinary kernel > > display driver. But thesse things are missing is devicetree?! But =20 >=20 > Yeah, the kernel just exposes a framebuffer and a special secret sauce > userspace program writes to that. Looking at that processor. It seems to have an EPDC like the i.MX6 has. Looking even further. The Kobo factory kernel for i.MX6SLL devices specifies fsl,imx7d-epdc as compatible for that. So if your display is just connected to that EPDC, then you could probably wire up things on top of my EPDC driver with DRM interface. So you still too need to run your own fork for the display?=20 >=20 > > that might need to learn to deal with regulator enabling/disabling. > >=20 > > Regulator always on is probably not desired here, either. =20 >=20 > Yeah, I **think** we don't need that >=20 You just need to add logic to enable/disable the regulator (if it is not wired up yet). But it is nothing from the perspective of mainline to worry about. Regards, Andreas