On Wed, Jul 15, 2026 at 06:07:56PM +0200, Hari Mishal wrote: > On Wed, Jul 15, 2026 at 5:50 PM Michael S. Tsirkin <[email protected]> wrote: > > > > On Wed, Jul 15, 2026 at 04:22:41PM +0200, Hari Mishal wrote: > > > nslots is derived from the ABS_MT_SLOT maximum reported by the > > > virtio device. A device could report a bogus maximum (e.g. -1) > > > making nslots = 0, which input_mt_init_slots() does not reject; > > > it returns success without allocating any slot storage, silently > > > leaving the device registered as multitouch capable with no > > > backing state. > > > > So let's disable multitouch instead? > > > > So rather than failing the whole probe, just warn and clear > ABS_MT_SLOT from absbit in that case, so the rest of the device > still registers? I took my lead from input_mt_init_slots(), which > has its own internal cap and returns -EINVAL when the device > reports more than 1024 slots. > Shall I modify that case to get the same "warn and disable > multitouch" for consistency, or is a hard failure better there since > it's a different type of bad device data?
I don't really know enough for sure but generally if the device can kinda work it's better than not working, and adding a capability to a device that driver can't use should generally just ignore the capability, not fail probe. > Happy to fix it either way! Just want to confirm before sending V2. > > Cheers, > Hari
