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[87.184.117.22]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48fe4c834besm56684565e9.3.2026.05.15.04.47.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 15 May 2026 04:47:53 -0700 (PDT) Message-ID: Date: Fri, 15 May 2026 13:47:52 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: Stefan Seyfried Content-Language: en-US To: LKML , "Kandpal, Suraj" Subject: [REGRESSION] bisected: 7.1rc1 breaks backlight control on Thinkpad T480 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi all, I found that 7.1rc1 broke the backlight control on my Thinkpad T480. Bisected it to > 40d2f5820951dee818d05c14677277048bd85f9f is the first bad commit > commit 40d2f5820951dee818d05c14677277048bd85f9f > Author: Suraj Kandpal > Date: Tue Feb 24 08:43:22 2026 +0530 > > drm/i915/backlight: Remove try_vesa_interface > > Some panels need VESA DPCD AUX backlight but VBT says otherwise. > This is why we try with Intel backlight interface over VESA backlight > interface. This causes a blankout on such panels without any fallback > mechanism. > Remove try_vesa_interface and use VESA AUX backlight interface as a > fallback mechanism. > While at in sneak in a small comment cleanup too. > > Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/15679 > Signed-off-by: Suraj Kandpal > Reviewed-by: Ankit Nautiyal > Link: https://patch.msgid.link/20260224031322.2568874-1-suraj.kandpal@intel.com > > drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 19 +++++++------------ > 1 file changed, 7 insertions(+), 12 deletions(-) Please revert :-) Best regards, -- Stefan Seyfried "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." -- Richard Feynman