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Fri, 25 Sep 2026 06:25:18 +0000 (UTC) From: Evan Lawrence To: Dmitry Torokhov Cc: Evan Lawrence , linux-input@vger.kernel.org, linux-api@vger.kernel.org, Miroslav Bendik Subject: Re: [PATCH v5] Input: synaptics - add pass-through mode for TrackPoint Message-ID: <20260925062454.102935-1-development@laserology.net> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260815004214.68767-1-development@laserology.net> References: <20260815004214.68767-1-development@laserology.net> Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Date: Fri, 25 Sep 2026 06:25:18 +0000 (UTC) X-CM-Envelope: MS4xfOnlRoYS6G4pB6HKufcKy2kROKC+YQJinOmtr9Z6ajAk0lUNUNCWxV6idVktJb/+ICrTXQyB6blu+4ii8UwiYr6/78SpBvBs13JhDNrBR8poCmzUn769 MJwaWVP/FTPbyXIIpqAiu88raxX9+CPDeiNHxbPhwSkzzCPKdF7U6vFcB2/oy6YCL+Sdw80U+PoLYkhyQy4S0tWiDq7nEXYF4mqdNGBcgXWMVImeN3miF5mB b+79TD2G7d423RulHr4BoRt7iwcFiOT9R8nucmwtTOIBZF85NOniQv54J1a43yypTOcKiCWSG8WCn3gy6uMbbQDU0idNQJYIFXnB32RdV5yHCYOp2QeBuHtC Y/1SO8JxDRKXPF9FQ/LRkw2LnoMNqT7AK+hYBjJPBLzC37fim23ElMUCKBucrPP3HTeEqnwm X-CM-Analysis: v=2.4 cv=ALriHGRn c=1 sm=1 tr=0 ts=6ab613cf a=bXe6bw2OB92olpQ1pPvang==:617 a=xqWC_Br6kY4A:10 a=NEAV23lmAAAA:8 a=8b8fbwVGRZi1C_-jfXoA:9 X-AuthUser: admin@laserology.net Hi Dmitry, Following up on this thread: I am pausing all work on transparent pass-through mode, including the v6 I mentioned (the ACK-waiting latency reduction). I'd rather not push a workaround once the real transport works. The reason is your original question. In my previous reply I said SMBus/RMI4 was not viable on the T14 Gen 1 because it stayed in PS/2 mode. That turned out to be a transport bug, not a device limitation: the AMD FCH needs the legacy SMB0001/ASF Host Notify path enabled before rmi_smbus can talk to the touchpad. With that in place, the T14 Gen 1 AMD now runs the touchpad (F12) and the TrackPoint (F03) natively on RMI4, with no transparent mode and no pass-through bandwidth limit. Both devices are working on a T14 Gen 1 AMD and on a P14s Gen 2a. That work is being carried in a machine-specific, not-yet-upstream repository together with Spencer Michaels, who did the original T14 Gen 2a reverse-engineering: https://github.com/SpencerMichaels/t14-amd-gen2-rmi I'll keep the transparent-mode series archived and would be glad to revive it for any machine where RMI4 genuinely cannot work -- but that no longer looks like the general answer to your question. Thanks for the review feedback along the way, and to Miroslav for the original transparent-mode work this was based on. Also, this was my first real foray into kernel work, and parts were LLM-assisted; I've reviewed and tested everything on the hardware. Thanks for the patience with a newcomer. Evan