[PATCH v2 4/9] drm/panthor: Implement optional reset

[Boris Brezillon]

On Tue, 25 Mar 2025 14:50:32 +0100
Marek Vasut <marex at denx.de> wrote:

> On 3/25/25 8:43 AM, Boris Brezillon wrote:
> > On Tue, 25 Mar 2025 00:37:59 +0100
> > Marek Vasut <marex at denx.de> wrote:
> >   
> >> On 3/24/25 9:43 AM, Boris Brezillon wrote:
> >>
> >> [...]
> >>  
> >>>> @@ -563,6 +585,7 @@ int panthor_device_suspend(struct device *dev)
> >>>>    
> >>>>    	panthor_devfreq_suspend(ptdev);
> >>>>    
> >>>> +	reset_control_assert(ptdev->resets);  
> >>>
> >>> Hm, that might be the cause of the fast reset issue (which is a fast
> >>> resume more than a fast reset BTW): if you re-assert the reset line on
> >>> runtime suspend, I guess this causes a full GPU reset, and the MCU ends
> >>> up in a state where it needs a slow reset (all data sections reset to
> >>> their initial state). Can you try to move the reset_control_[de]assert
> >>> to the unplug/init functions?  
> >> Is it correct to assume , that if I remove all reset_control_assert()
> >> calls (and keep only the _deassert() calls), the slow resume problem
> >> should go away too ?  
> > 
> > Yeah, dropping the _assert()s should do the trick.  
> Hmmm, no, that does not help. I was hoping maybe NXP can chime in and 
> suggest something too ?

Can you try keep all the clks/regulators/power-domains/... on after
init, and see if the fast resume works with that. If it does,
re-introduce one resource at a time to find out which one causes the
MCU to lose its state.