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[2001:4c4e:24d0:6700:5d2c:718b:790:18c4]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2698016c265sm186914275ad.49.2025.09.24.03.44.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 24 Sep 2025 03:44:15 -0700 (PDT) Message-ID: Date: Wed, 24 Sep 2025 12:44:08 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] drm/amd/display: Reject YUV422 encoding over DP on DCE To: Alex Deucher Cc: amd-gfx@lists.freedesktop.org, alexander.deucher@amd.com, alex.hung@amd.com, harry.wentland@amd.com, siqueira@igalia.com References: <20250919081419.9034-1-timur.kristof@gmail.com> Content-Language: en-US From: =?UTF-8?Q?Timur_Krist=C3=B3f?= In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-BeenThere: amd-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussion list for AMD gfx List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: amd-gfx-bounces@lists.freedesktop.org Sender: "amd-gfx" On 9/19/25 17:09, Alex Deucher wrote: > On Fri, Sep 19, 2025 at 4:14 AM Timur Kristóf wrote: >> >> Mark YUV422 unsupported over DP on DCE to work around a >> regression caused by the recent YUV422 fallback patch. >> >> See https://gitlab.freedesktop.org/drm/amd/-/issues/4585 >> >> The recent YUV422 fallback breaks DisplayPort on DCE6-10 because >> it can select a high refresh rate mode with YUV422 and 6 BPC, >> which is apparently not actually supported by the HW, causing >> it to boot to a "no signal" screen. >> >> Tested with a Samsung Odyssey G7 on the following GPUs: >> >> - Cape Verde (DCE 6): affected >> - Tonga (DCE 10): affected >> - Polaris (DCE 11.2): not affected >> - Vega (DCE 12): not affected >> >> Polaris and Vega are not affected because the same mode >> gets rejected by other parts of the code base, possibly the >> bandwidth calculation which exists for DCE11+ but not older HW. >> >> It is not documented whether YUV422 is actually supported over DP >> on DCE, but considering that this encoding was never used before, >> and that YUV420 is already marked unsupported, probably not. >> >> Signed-off-by: Timur Kristóf > > Fixes: db291ed1732e02 ("drm/amd/display: Add fallback path for YCBCR422") > Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4585 > Acked-by: Alex Deucher > > Would be good to get feedback from the display team on what the actual > capabilities are, but seems reasonable to me. > > Alex Please disregard this patch. I will send a different patch which will instead reject modes that would require a pixel clock higher than the maximum display clock. Thanks, Timur