On Mon, 2019-08-19 at 21:49 +0200, Paul Pawlowski wrote: > Hello, > Do DMA mappings get cleared when the device is suspended to RAM? A > device I'm writing a driver for requires the DMA addresses not to > change after a resume and trying to use DMA memory allocated before > the suspend causes a device error. Is there a way to persist the > mappings through a suspend? What are you actually asking? The state of the IOMMU mappings should be saved and restored on suspend/resume. However, whether mappings that are inside actual PCI devices are saved and restored depends on the actual device. In general we don't expect them to remember in- flight I/O which is why I/O is quiesced before devices are suspended, so the device should be inactive and any I/O in the upper layers will be mapped on resume. The DMA addresses of the mailboxes are usually saved and restored, but how is up to the driver. James
