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Fri, 13 Nov 2026 08:08:46 -0800 (PST) Received: from localhost ([2a00:79e0:2ebe:8:48f1:7a0b:9bfb:4205]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-1b5031468b7sm9958884c88.5.2026.11.13.08.08.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Nov 2026 08:08:44 -0800 (PST) Date: Fri, 13 Nov 2026 08:08:44 -0800 Message-ID: <563ab45500cc33d06b7973075635d0dc@gmail.com> From: Dmitry Torokhov To: Eduardo Henrique Teixeira Cc: Dmitry Mikushin , linux-input@vger.kernel.org, lovekeshsolanki00@gmail.com Subject: Re: [BUG] ThinkPad T490 Synaptics TM3471-020 input lag and missed taps with SMBus/RMI4 In-Reply-To: References: X-Mailing-List: linux-input@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Disposition: inline Hi Eduardo, On Fri, Oct 30, 2026 at 06:10:50PM -0700, Eduardo Henrique Teixeira wrote: > I would like to report a possible issue with Synaptics InterTouch > (SMBus/RMI4) on the Lenovo ThinkPad T490. > > Hardware: > > - Model: Lenovo ThinkPad T490 (20N3S5DU1N) > - Touchpad: Synaptics TM3471-020 > - Firmware ID: 3972349 > - BIOS: 1.85 > - Distribution: Ubuntu > - Kernel: 7.3.0-10-generic > > Symptoms: > > The touchpad exhibits noticeable delays when detecting finger contact, > sometimes perceived as approximately 200–500 ms before pointer movement > begins. > > Short taps frequently fail to register as mouse clicks. Longer touches are > more likely to be recognized. Dmitry Mikushin (CCed) recently fixed a performance bottleneck on Synaptics TM3471 over SMBus where rmi_f12 was reading the entire 79-byte F12 data packet on every attention interrupt (requiring three SMBus block reads and ~17.4 ms per frame, capping the report rate at ~43 Hz), even though only the first 32 bytes (Data1) are used. Could you please test his two rmi_f12 patches (now in the input next branch) that limit the F12 read to Data1 (~7.3 ms, ~65 Hz) and see if they resolve the input lag and missed taps on your T490: https://lore.kernel.org/linux-input/20261026142648.2567233-2-dmitry@kernelgen.org/ https://lore.kernel.org/linux-input/20261026142648.2567233-3-dmitry@kernelgen.org/ Thanks. -- Dmitry