From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A783C606A31D for ; Sun, 15 Nov 2026 14:07:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=ERCctqRo Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id E866F10E29E; Sun, 15 Nov 2026 14:06:58 +0000 (UTC) Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by gabe.freedesktop.org (Postfix) with ESMTPS id 0948010E26E; Sun, 15 Nov 2026 14:06:52 +0000 (UTC) Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id DFB29456AF; Sun, 15 Nov 2026 14:06:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 35BEE1F000C4; Sun, 15 Nov 2026 14:06:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794751611; bh=RwSOhU1sXIw9Fgw/IOjebI38Eb90DcWzMsDdecSXIOc=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=ERCctqRoahls0W1xfobOaqi2LNTtl20O0HPndcZqw0pLZX7pXweipZVbno31JeiIc rxCjeqffRccsRb1BajgeWD9SCvIpRMtfZgJ9AroL4nm60JFqI5WaMz9OgpuXMNa/0F NGGZ2XQbHevfFUgWn1LKEA2Fz7UawSzWOdsqfeqPqzw3IWZCMOQIqgKwsxRnX2v3zT tJgzByz5+0UBC6czxN9Ekn/Z+WzIu4rRGoSrApHS39ql/S98//DOKjVnlUoygRjTg5 U1NJYzaxQO1FATwphqP2bfkpY/gXe3rBo5FUPf3CujfVuT4SpBA/MLFztPCdBwY93q Ih1OXOscY4Lxw== Message-ID: Date: Sun, 15 Nov 2026 08:06:50 -0600 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] drm/amd/display: Route connector DDC over AUX for native DP sinks Content-Language: en-US To: simonit.orig@gmail.com, Richard Hughes Cc: Harry Wentland , Leo Li , Alex Deucher , dri-devel@lists.freedesktop.org, Wayne Lin , amd-gfx@lists.freedesktop.org References: <20261103-superm1-amdgpu-ddc-v2-1-7bde6d004382@kernel.org> <20261115082042.1902826-1-Wayne.Lin@amd.com> From: Mario Limonciello In-Reply-To: <20261115082042.1902826-1-Wayne.Lin@amd.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "dri-devel" X-Spam-Status: No, score=-22.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 11/15/26 02:20, Wayne Lin wrote: > Reviewed-by: Wayne Lin Thanks Wayne. Simon, Richard, Can you please check that this resolves the issue raised? Thanks, > > On Tue, 03 Nov 2026 08:18:40 -0600, Mario Limonciello wrote: >> On DisplayPort and eDP connectors DDC is tunneled over the AUX channel, >> but the connector's "ddc" adapter ("AMDGPU DM i2c hw bus N") always >> drives the physical i2c pins, which don't reach a native DP sink. The >> AUX backed adapter ("AMDGPU DM aux hw bus N") does, so userspace such as >> fwupd, which uses the "ddc" sysfs link for DDC/CI, has to work around >> this. >> >> Keep a single i2c bus per connector and pick the transport per transfer >> based on the detected sink: if the sink is a native DP/eDP/MST sink, >> forward the transfer to the AUX adapter, otherwise (DVI/HDMI, including >> DP++ with a passive adapter) use the hw i2c engine as before. >> >> Reported-by: simonit.orig@gmail.com >> Closes: https://github.com/fwupd/fwupd/pull/11308 >> Signed-off-by: Mario Limonciello >> --- >> Changes in v2: >> - Check which i2c bus to use on the fly instead of changing static symlink to >> avoid regressing passive adapters. >> - Link to v1: https://patch.msgid.link/20261102-superm1-amdgpu-ddc-v1-1-9c5cb4a4f62d@amd.com >> --- >> .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c | 16 ++++++++++++++++ >> 1 file changed, 16 insertions(+) >> >> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c >> index b498fc5fbb140..678caffa3d120 100644 >> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c >> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c >> @@ -3373,6 +3373,22 @@ STATIC_IFN_KUNIT int amdgpu_dm_i2c_xfer(struct i2c_adapter *i2c_adap, >> int i; >> int result = -EIO; >> >> + if (!i2c->oem) { >> + struct dc_link *link = ddc_service->link; >> + struct amdgpu_dm_connector *aconnector = link->priv; >> + >> + /* >> + * DDC to a native DisplayPort sink is tunneled over the AUX >> + * channel; the physical i2c pins only reach DVI/HDMI sinks >> + * (e.g. DP++ with a passive adapter). Route accordingly so >> + * the connector's single "ddc" bus works for either sink. >> + */ >> + if (aconnector && link->local_sink && >> + dc_is_dp_signal(link->local_sink->sink_signal) && >> + aconnector->dm_dp_aux.aux.ddc.algo) >> + return i2c_transfer(&aconnector->dm_dp_aux.aux.ddc, msgs, num); >> + } >> + >> if (!ddc_service->ddc_pin) >> return result; >> >> >> --- >> base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4 >> change-id: 20261102-superm1-amdgpu-ddc-63f0eb10c022 >> >> Best regards, >> -- >> Mario Limonciello >> >>