On Fri, Nov 1, 2024 at 9:54 AM <qiang4.zhang@xxxxxxxxxxxxxxx> wrote: > > From: Qiang Zhang <qiang4.zhang@xxxxxxxxx> > > Virtio core unconditionally reset and restore status for all virtio > devices before calling restore method. This breaks some virtio drivers > which don't need to do anything in suspend and resume because they > just want to keep device state retained. The challenge is how can driver know device doesn't need rest. For example, PCI has no_soft_reset which has been done in the commit "virtio: Add support for no-reset virtio PCI PM". And there's a ongoing long discussion of adding suspend support in the virtio spec, then driver know it's safe to suspend/resume without reset. > > Virtio GPIO is a typical example. GPIO states should be kept unchanged > after suspend and resume (e.g. output pins keep driving the output) and > Virtio GPIO driver does nothing in freeze and restore methods. But the > reset operation in virtio_device_restore breaks this. Is this mandated by GPIO or virtio spec? If yes, let's quote the revelant part. > > Since some devices need reset in suspend and resume while some needn't, > create a new helper function for the original reset and status restore > logic so that virtio drivers can invoke it in their restore method > if necessary. How are those drivers classified? > > Signed-off-by: Qiang Zhang <qiang4.zhang@xxxxxxxxx> Thanks
