Hi Yufei, On Sun, Nov 07, 2021 at 03:02:27PM -0500, Yufei Du wrote: > Hi Dmitry, > > I am a user currently suffering from the firmware bug that causes my > trackpoint to be unusable on my Lenovo X13 Gen 1 AMD. I tested this patch in > the latest 5.15 mainline kernel tree and can possibly answer your questions > regarding the patch. > > > I think this will reject X coordinates in range [0, 127]. Is this really > > what is needed? > > As Phoenix explained in his reply, the patch will reject X and Y coordinates > larger than 127 or smaller than -127. This is because the most significant > bit of packet[1] (for X) and packet[2] (for Y) are inverse of the sign bit. > Although I do not have the formal design specification of the device, I > tried pushing the trackpoint as hard as I could, and the X and Y coordinates > never go beyond +/-127 normally, so I believe that this patch would not > cause any functionality issue. > > > What kind of patterns are you observing when firmware > > misreports coordinates? > > Here is a sample log I observed (with elantech.debug set to 2 for more > debugging messages): > psmouse serio1: elantech: PS/2 packet [10 00 80 26 f9 0a] > psmouse serio1: elantech: PS/2 packet [10 00 80 26 00 80] > psmouse serio1: elantech: PS/2 packet [10 00 80 00 00 00] > psmouse serio1: Touchpad at isa0060/serio1/input0 lost sync at byte 6 > psmouse serio1: elantech: PS/2 packet [10 00 80 26 f8 0b] > psmouse serio1: Touchpad at isa0060/serio1/input0 - driver resynced. > > The first packet is a valid packet. The second packet is the incorrect > packet that this patch prevents. The third packet is a corrupted packet that > psmouse detects (as shown in the "lost sync" message), and the fourth packet > is a valid packet again. Without the patch, the second packet would cause > the cursor to jump to the edge of the screen. > > So far, all my logs of this issue show the same pattern of a jumpy incorrect > packet followed by a corrupted packet that causes psmouse to lose sync. > There are more logs and discussions in the BugZilla entry here: > https://bugzilla.kernel.org/show_bug.cgi?id=209167 > > Hope my explanation helped a bit. Sorry I lost track of this patch. Can I add your Tested-by to it before applying? Thanks. -- Dmitry
