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Fri, 30 Jan 2026 19:53:42 +0000 Message-ID: <04559485-ecb6-4132-91ee-00c7c6288e16@amd.com> Date: Fri, 30 Jan 2026 12:53:40 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 07/14] drm/amd/display: Implement DDC probe over AUX channel To: =?UTF-8?Q?Timur_Krist=C3=B3f?= , amd-gfx@lists.freedesktop.org, Alexander.Deucher@amd.com, Christian.Koenig@amd.com, Mario Limonciello , Ivan Lipski , Prike Liang , Leo Li , Ray Wu , siqueira@igalia.com References: <20260126210837.21885-1-timur.kristof@gmail.com> <20260126210837.21885-8-timur.kristof@gmail.com> Content-Language: en-US From: Alex Hung In-Reply-To: <20260126210837.21885-8-timur.kristof@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: MW4PR03CA0060.namprd03.prod.outlook.com (2603:10b6:303:8e::35) To DM4PR12MB8476.namprd12.prod.outlook.com (2603:10b6:8:17e::15) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM4PR12MB8476:EE_|MN2PR12MB4095:EE_ X-MS-Office365-Filtering-Correlation-Id: c3ff6a51-bb30-418a-5203-08de60394544 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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However, in order to support > external DP bridge encoders found in CIK APUs, it needs to work > over the AUX channel too. > > Signed-off-by: Timur Kristóf > --- > drivers/gpu/drm/amd/display/dc/link/link_detection.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/amd/display/dc/link/link_detection.c b/drivers/gpu/drm/amd/display/dc/link/link_detection.c > index 1585cce65b0e..e1d568905581 100644 > --- a/drivers/gpu/drm/amd/display/dc/link/link_detection.c > +++ b/drivers/gpu/drm/amd/display/dc/link/link_detection.c > @@ -903,11 +903,18 @@ static bool link_detect_evaluate_edid_header(uint8_t edid_header[8]) > */ > static bool link_detect_ddc_probe(struct dc_link *link) > { > + enum signal_type signal = link_detect_sink_signal_type(link, DETECT_REASON_HPD); > + enum ddc_transaction_type transaction_type = get_ddc_transaction_type(signal); > + > if (!link->ddc) > return false; > > + set_ddc_transaction_type(link->ddc, transaction_type); > + > uint8_t edid_header[8] = {0}; > - bool ddc_probed = i2c_read(link->ddc, 0x50, edid_header, sizeof(edid_header)); > + uint8_t zero = 0; > + bool ddc_probed = > + link_query_ddc_data(link->ddc, 0x50, &zero, 1, edid_header, sizeof(edid_header)); Please move variable declaration to beginning of the function. Thanks. > > if (!ddc_probed) > return false;