On Mon, May 06, 2024 at 09:29:36AM +0200, Maxime Ripard wrote: > Hi Laurent, Sean, > > On Sat, May 04, 2024 at 03:21:18PM GMT, Laurent Pinchart wrote: > > On Fri, May 03, 2024 at 05:54:32PM -0400, Sean Anderson wrote: > > > I have discovered a bug in the displayport driver on drm-misc-next. To > > > trigger it, run > > > > > > echo fd4a0000.display > /sys/bus/platform/drivers/zynqmp-dpsub/unbind > > > > > > The system will become unresponsive and (after a bit) splat with a hard > > > LOCKUP. One core will be unresponsive at the first zynqmp_dp_read in > > > zynqmp_dp_bridge_detect. > > > > > > I believe the issue is due the registers being unmapped and the block > > > put into reset in zynqmp_dp_remove instead of zynqmp_dpsub_release. > > > > That is on purpose. Drivers are not allowed to access the device at all > > after .remove() returns. > > It's not "on purpose" no. Drivers indeed are not allowed to access the > device after remove, but the kernel shouldn't crash. This is exactly > why we have drm_dev_enter / drm_dev_exit. I didn't mean the crash was on purpose :-) It's the registers being unmapped that is, as nothing should touch those registers after .remove() returns. -- Regards, Laurent Pinchart
