On Wed, Jan 11, 2017 at 01:27:30PM -0500, Stefan Berger wrote: > On 01/11/2017 01:03 PM, Jason Gunthorpe wrote: > >On Wed, Jan 11, 2017 at 11:00:43AM +0100, Andreas Fuchs wrote: > > > >>could we please get an ioctl, that switches the "mode" of the fd entirely. > >>I'd like to see the write()/read() support still intact. > >>All my current code uses main-loop based poll on the fd and I don't want > >>to be force to start using threads... > >We currently do not support poll in the kernel for /dev/tpmX. > > > >ie we do not supply a poll method for 'struct file_operations'. > > > >Even worse, the current implementation blocks returning from write() > >until the TPM has completed its work, so it doesn't even make sense to > >combine it with poll. > > Newer applications could issue an ioctl() after the open() to unblock the > write().
The ioctl api I outlined could support poll by having userspace set the rxbuf = NULL. The kernel would then launch the tx async and provide poll support to allow read() to return the result once the tpm has finished. This can be added as a new capability down the road.. Jason
