From patchwork Thu Aug 16 10:53:16 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hans Verkuil X-Patchwork-Id: 10567301 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E6EA01575 for ; Thu, 16 Aug 2018 10:53:28 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D4A2D2A8F3 for ; Thu, 16 Aug 2018 10:53:28 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C901B2A8F9; Thu, 16 Aug 2018 10:53:28 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 2861D2A8F7 for ; Thu, 16 Aug 2018 10:53:27 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 247CD896B5; Thu, 16 Aug 2018 10:53:24 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from lb1-smtp-cloud9.xs4all.net (lb1-smtp-cloud9.xs4all.net [194.109.24.22]) by gabe.freedesktop.org (Postfix) with ESMTPS id C4852896BF for ; Thu, 16 Aug 2018 10:53:22 +0000 (UTC) Received: from marune.fritz.box ([IPv6:2001:983:e9a7:1:a179:5a3f:99ad:b7a]) by smtp-cloud9.xs4all.net with ESMTPA id qFu3fvheqEJtcqFu4fXrGi; Thu, 16 Aug 2018 12:53:21 +0200 From: Hans Verkuil To: linux-media@vger.kernel.org Subject: [PATCH 2/5] drm_dp_cec: add note about good MegaChips 2900 CEC support Date: Thu, 16 Aug 2018 12:53:16 +0200 Message-Id: <20180816105319.6411-3-hverkuil@xs4all.nl> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180816105319.6411-1-hverkuil@xs4all.nl> References: <20180816105319.6411-1-hverkuil@xs4all.nl> X-CMAE-Envelope: MS4wfDR2MC6pSDURczrrGCwlmYEC0b+Rgexz8MOC1a6er7JUMU8FYPYypWYqq0YOftjLiT2DUfRD6E3RK0ORzSe4dvPeezgHHUqg5ujUxUswImbjYgxNj9de twllxQEfMydG9Beq2lSRSDyWcO3iXmdP4asme5ljuwWr+l4bmbJrkeb8W+FkM5p6TTymPwoH8BkyRGU0mdamzJpBJ3J59L+dDxtYLikxDgIDZIg/PifAhW3K pbmqgNa9hfzpKrQNhejaYZkVtv5w5k591f0bJpOih6Obx/pWz+ti6bXFC8bV91Rpma/pGd4FpX7QVJNFqd1aN+i2/5/AE3SQyq+AbPJkkIc6mXr2diK04oiQ pccorL+i/ocuqdSdQyYL+hKtadZmVQ== X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: nouveau@lists.freedesktop.org, Hans Verkuil , amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org MIME-Version: 1.0 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP From: Hans Verkuil A big problem with DP CEC-Tunneling-over-AUX is that it is tricky to find adapters with a chipset that supports this AND where the manufacturer actually connected the HDMI CEC line to the chipset. Add a mention of the MegaChips 2900 chipset which seems to support this feature well. Signed-off-by: Hans Verkuil --- drivers/gpu/drm/drm_dp_cec.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_dp_cec.c b/drivers/gpu/drm/drm_dp_cec.c index 1407b13a8d5d..8a718f85079a 100644 --- a/drivers/gpu/drm/drm_dp_cec.c +++ b/drivers/gpu/drm/drm_dp_cec.c @@ -16,7 +16,9 @@ * here. Quite a few active (mini-)DP-to-HDMI or USB-C-to-HDMI adapters * have a converter chip that supports CEC-Tunneling-over-AUX (usually the * Parade PS176), but they do not wire up the CEC pin, thus making CEC - * useless. + * useless. Note that MegaChips 2900-based adapters appear to have good + * support for CEC tunneling. Those adapters that I have tested using + * this chipset all have the CEC line connected. * * Sadly there is no way for this driver to know this. What happens is * that a /dev/cecX device is created that is isolated and unable to see