Re: [PATCH 3/3] drm/panthor: Fix undefined panthor_device_suspend/resume symbol issue

[Boris Brezillon <boris.brezillon@collabora.com>]

On Mon, 11 Mar 2024 13:11:28 +0000
Robin Murphy <robin.murphy@arm.com> wrote:

> On 2024-03-11 11:52 am, Boris Brezillon wrote:
> > On Mon, 11 Mar 2024 13:49:56 +0200
> > Jani Nikula <jani.nikula@linux.intel.com> wrote:
> >   
> >> On Mon, 11 Mar 2024, Boris Brezillon <boris.brezillon@collabora.com> wrote:  
> >>> On Mon, 11 Mar 2024 13:05:01 +0200
> >>> Jani Nikula <jani.nikula@linux.intel.com> wrote:
> >>>     
> >>>> This breaks the config for me:
> >>>>
> >>>>    SYNC    include/config/auto.conf.cmd
> >>>>    GEN     Makefile
> >>>> drivers/iommu/Kconfig:14:error: recursive dependency detected!
> >>>> drivers/iommu/Kconfig:14:	symbol IOMMU_SUPPORT is selected by DRM_PANTHOR
> >>>> drivers/gpu/drm/panthor/Kconfig:3:	symbol DRM_PANTHOR depends on PM
> >>>> kernel/power/Kconfig:183:	symbol PM is selected by PM_SLEEP
> >>>> kernel/power/Kconfig:117:	symbol PM_SLEEP depends on HIBERNATE_CALLBACKS
> >>>> kernel/power/Kconfig:35:	symbol HIBERNATE_CALLBACKS is selected by XEN_SAVE_RESTORE
> >>>> arch/x86/xen/Kconfig:67:	symbol XEN_SAVE_RESTORE depends on XEN
> >>>> arch/x86/xen/Kconfig:6:	symbol XEN depends on PARAVIRT
> >>>> arch/x86/Kconfig:781:	symbol PARAVIRT is selected by HYPERV
> >>>> drivers/hv/Kconfig:5:	symbol HYPERV depends on X86_LOCAL_APIC
> >>>> arch/x86/Kconfig:1106:	symbol X86_LOCAL_APIC depends on X86_UP_APIC
> >>>> arch/x86/Kconfig:1081:	symbol X86_UP_APIC prompt is visible depending on PCI_MSI
> >>>> drivers/pci/Kconfig:39:	symbol PCI_MSI is selected by AMD_IOMMU
> >>>> drivers/iommu/amd/Kconfig:3:	symbol AMD_IOMMU depends on IOMMU_SUPPORT  
> >>>
> >>> Uh, I guess we want a "depends on IOMMU_SUPPORT" instead of "select
> >>> IOMMU_SUPPORT" in panthor then.  
> >>
> >> That works for me.  
> > 
> > Let's revert the faulty commit first. We'll see if Steve has a
> > different solution for the original issue.  
> 
> FWIW, the reasoning in the offending commit seems incredibly tenuous. 
> There are far more practical reasons for building an arm/arm64 kernel 
> without PM - for debugging or whatever, and where one may even still 
> want a usable GPU, let alone just a non-broken build - than there are 
> for building this driver for x86. Using pm_ptr() is trivial, and if you 
> want to support COMPILE_TEST then there's really no justifiable excuse 
> not to.

The problem is not just about using pm_ptr(), but also making sure
panthor_device_resume/suspend() are called called in the init/unplug
path when !PM, as I don't think the PM helpers automate that for us. I
was just aiming for a simple fix that wouldn't force me to test the !PM
case...

> 
> Thanks,
> Robin.