Hi Arindam, On Wed, Mar 29, 2017 at 07:15:42AM +0000, Nath, Arindam wrote: > Joerg, as per my limited understanding of ATS, the ATC will respond to > invalidation requests after making sure there are no in-flight DMA > transactions with the address requested by IOMMU to be invalidated. > Now since the IOMMU was sending invalidate command to GPU even though > there was no explicit page unmapping request from the graphics > subsystem, we _might_ end up in a situation where the ATC takes longer > than the invalidation timeout to respond to IOMMU. The maximum wait-time in the loop is 100ms. This should be more than enough for the ATC to complete any in-flight transaction and flush its internal TLB. If that is not enough, there is almost certainly something wrong with the hardware. Joerg
