[PATCH v5 1/2] drm/panthor: Reset queue slots if termination fails

[Ashley Smith]

On Tue, 03 Jun 2025 12:09:44 +0100 Liviu Dudau <liviu.dudau at arm.com> wrote:
 > On Tue, Jun 03, 2025 at 10:49:31AM +0100, Ashley Smith wrote: 
 > > This fixes a bug where if we timeout after a suspend and the termination 
 > > fails, due to waiting on a fence that will never be signalled for 
 > > example, we do not resume the group correctly. The fix forces a reset 
 > > for groups that are not terminated correctly. 
 >  
 > I have a question on the commit message: you're describing a situation where 
 > a fence will *never* be signalled. Is that a real example? I thought this is 
 > not supposed to ever happen! Or are you trying to say that the fence signalling 
 > happens after the timeout?

This covers cases where a fence is never signalled. It shouldn't happen, but we have found this in some situations with a FW hang. Since queue_suspend_timeout() is only called on state update, if a suspend/terminate fails due to a FW hang for example this will leave delayed work, possibly leading to an incorrect queue_timeout_work(). Maybe I should not have used the word bug, it's more choosing a failsafe path.