On Mon, Jan 13, 2020 at 9:51 AM Jordan Crouse <jcrouse@xxxxxxxxxxxxxx> wrote: > > On Mon, Jan 13, 2020 at 10:36:05AM -0500, Brian Ho wrote: > > + > > + vaddr = base_vaddr + args->offset; > > + > > + /* Assumes WC mapping */ > > + ret = wait_event_interruptible_timeout( > > + gpu->event, *vaddr >= args->value, remaining_jiffies); > > I feel like a barrier might be needed before checking *vaddr just in case you > get the interrupt and wake up the queue before the write posts from the > hardware. > if the gpu is doing posted (or cached) writes, I don't think there is even a CPU side barrier primitive that could wait for that? I think we rely on the GPU not interrupting the CPU until the write is posted BR, -R
