On Fri, Mar 27, 2020 at 8:10 AM Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx> wrote: > > Hi Robin, > > Thanks for taking a look at this. > > On 2020-03-27 19:42, Robin Murphy wrote: > > On 2020-03-27 1:28 pm, Sai Prakash Ranjan wrote: > >> Currently on reboot/shutdown, the following messages are > >> displayed on the console as error messages before the > >> system reboots/shutdown. > >> > >> On SC7180: > >> > >> arm-smmu 15000000.iommu: removing device with active domains! > >> arm-smmu 5040000.iommu: removing device with active domains! > >> > >> Demote the log level to debug since it does not offer much > >> help in identifying/fixing any issue as the system is anyways > >> going down and reduce spamming the kernel log. > > > > I've gone back and forth on this pretty much ever since we added the > > shutdown hook - on the other hand, if any devices *are* still running > > in those domains at this point, then once we turn off the SMMU and let > > those IOVAs go out on the bus as physical addresses, all manner of > > weirdness may ensue. Thus there is an argument for *some* indication > > that this may happen, although IMO it could be downgraded to at least > > dev_warn(). > > > > Any pointers to the weirdness here after SMMU is turned off? > Because if we look at the call sites, device_shutdown is called > from kernel_restart_prepare or kernel_shutdown_prepare which would > mean system is going down anyways, so do we really care about these > error messages or warnings from SMMU? > > arm_smmu_device_shutdown > platform_drv_shutdown > device_shutdown > kernel_restart_prepare > kernel_restart > I'd guess that drm/msm is not detaching all of it's UNMANAGED domains in shutdown. Although *presumably* the device_link stuff would prevent the SMMU from shutting down while gpu/display is still active? If not I think we have bigger problems. I hadn't really noticed the error msgs before, not sure if that is just because the screen is off by the time they happen or if they are a new warning.. BR, -R
