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=-1.0 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 2DAF9C43387 for ; Thu, 20 Dec 2018 19:06:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0621C218FF for ; Thu, 20 Dec 2018 19:06:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388918AbeLTTGv (ORCPT ); Thu, 20 Dec 2018 14:06:51 -0500 Received: from mx2.suse.de ([195.135.220.15]:60548 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725785AbeLTTGu (ORCPT ); Thu, 20 Dec 2018 14:06:50 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 65B00B0B1; Thu, 20 Dec 2018 19:06:48 +0000 (UTC) Message-ID: <3df5afdfe9fe709fad1a4ae565692028c437beed.camel@suse.de> Subject: Re: [PATCH v2] drm/panel: rpi-touchscreen: Add backlight support From: Nicolas Saenz Julienne To: Gordon Hollingworth , Eric Anholt Cc: David Airlie , Thierry Reding , afaerber@suse.de, agraf@suse.de, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, stefan.wahren@i2se.com Date: Thu, 20 Dec 2018 20:06:45 +0100 In-Reply-To: References: <20181219112033.31064-1-nsaenzjulienne@suse.de> <87tvj8dp60.fsf@anholt.net> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-B5ikKgrafLfFK2k6vz3c" User-Agent: Evolution 3.30.2 Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-B5ikKgrafLfFK2k6vz3c Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2018-12-20 at 18:36 +0000, Gordon Hollingworth wrote: > Assuming this is using the firmware interface then yes it's fine. If > it is using the i2c directly then it's possible to clash with the GPU > driving the camera Well we're already in such a situation without this patch, as the panel enables the back-light though the I2C lines. This is only enabled by an overlay, it's left to the user's discretion. As commented previously by Alex Graf and given the constraints, I think that it would make sense to start considering both options as good (using FW & direct I2C access). We are defaulting to the FW based one, but providing support/overlays for the direct access doesn't seem a bad compromise to me. I do understand Gordon's concerns. Maybe it would be nice for the firmware to detect device tree nodes accessing I2C0 and disable the camera. Or providing a FW configuration option. Kind regards, Nicolas --=-B5ikKgrafLfFK2k6vz3c Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEErOkkGDHCg2EbPcGjlfZmHno8x/4FAlwb6EUACgkQlfZmHno8 x/5Hkwf/Q+Uam+zGriPGsJ6mIYD6ttPC1liJQE2TtQboC077phvwpVKikG26cNtX riRdFVJpNNHg69c1OBR7OZ1Jhrm4ck32Xop13iO/fmr0rdaQARTpv6Jd6fDcqSqG lfgQA4tWsudvGGWw/QpFKqxfRhUCw7ieB/bhYYjHWzajEYBzPQcpVhwF8CFQJKNY QureELDGGj0OmuI3Xn4UUWRjq9lrqvehazz28ud8E4Ane0azAlNGeumrAHuXT3g5 Uc/hULeXl3pwaFa/y73jPWH80MK4/CPg3kBnwZPtC/7JCzfcruTFLnUhYoIGbJBI Ksf2XguMb48R9Ri+aB4ekNxscgpGIQ== =kwGm -----END PGP SIGNATURE----- --=-B5ikKgrafLfFK2k6vz3c--