On 18/03/2024 14:18, Boris Brezillon wrote: > On Mon, 18 Mar 2024 13:49:52 +0000 > Steven Price <steven.price@xxxxxxx> wrote: > >> On 18/03/2024 13:08, Boris Brezillon wrote: >>> On Mon, 18 Mar 2024 11:31:05 +0000 >>> Steven Price <steven.price@xxxxxxx> wrote: >>> >>>> On 18/03/2024 08:58, Boris Brezillon wrote: >>>>> Putting a hard dependency on CONFIG_PM is not possible because of a >>>>> circular dependency issue, and it's actually not desirable either. In >>>>> order to support this use case, we forcibly resume at init time, and >>>>> suspend at unplug time. >>>>> >>>>> Reported-by: kernel test robot <lkp@xxxxxxxxx> >>>>> Closes: https://lore.kernel.org/oe-kbuild-all/202403031944.EOimQ8WK-lkp@xxxxxxxxx/ >>>>> Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx> >>>> >>>> Reviewed-by: Steven Price <steven.price@xxxxxxx> >>>> >>>>> --- >>>>> Tested by faking CONFIG_PM=n in the driver (basically commenting >>>>> all pm_runtime calls, and making the panthor_device_suspend/resume() >>>>> calls unconditional in the panthor_device_unplug/init() path) since >>>>> CONFIG_ARCH_ROCKCHIP selects CONFIG_PM. Seems to work fine, but I >>>>> can't be 100% sure this will work correctly on a platform that has >>>>> CONFIG_PM=n. >>>> >>>> The same - I can't test this properly :( >>>> >>>> Note that the other option (which AFAICT doesn't cause any problems) is >>>> to "select PM" rather than depend on it - AIUI the 'select' dependency >>>> is considered in the opposite direction by kconfig so won't cause the >>>> dependency loop. >>> >>> Doesn't seem to work with COMPILE_TEST though? I mean, we need >>> something like >>> >>> depends on ARM || ARM64 || (COMPILE_TEST && PM) >>> ... >>> select PM >>> >>> but kconfig doesn't like that >> >> Why do we need the "&& PM" part? Just: >> >> depends on ARM || ARM64 || COMPILE_TEST >> ... >> select PM >> >> Or at least that appears to work for me. > > Uh, you're right, sorry for the brain fart. This is being said, I > see no other driver selecting the PM option directly (if you grep for > 'select PM' in drivers/, you'll find occurrences in drivers/soc, but > those are under ARCH_/SOC_ options, which means they are indirectly > arch/platform dependent, not driver dependent). I'm really not sure > selecting PM here from a driver is right to be honest. Yeah, I'm not very convinced about that either. It's just a pain that the code is going to go untested. >> >>> drivers/gpu/drm/panthor/Kconfig:3:error: recursive dependency detected! >>> drivers/gpu/drm/panthor/Kconfig:3: symbol DRM_PANTHOR depends on >>> PM kernel/power/Kconfig:183: symbol PM is selected by DRM_PANTHOR >>> >>> which id why I initially when for a depends on PM >>> >>> >>>> Of course if there is actually anyone who has a >>>> platform which can be built !CONFIG_PM then that won't help. But the >>>> inability of anyone to actually properly test this configuration does >>>> worry me a little. >>> >>> Well, as long as it doesn't regress the PM behavior, I think I'm happy >>> to take the risk. Worst case scenario, someone complains that this is >>> not working properly when they do the !PM bringup :-). >> >> Indeed, I've no objection to this patch - although I really should have >> compiled tested it as Robin pointed out ;) >> >> But one other thing I've noticed when compile testing it - we don't >> appear to have fully fixed the virt_to_pfn() problem. On x86 with >> COMPILE_TEST I still get an error. Looking at the code it appears that >> virt_to_pfn() isn't available on x86... it overrides asm/page.h and >> doesn't provide a definition. The definition on x86 is hiding in >> asm/xen/page.h. > > Looks like the kbuild bot didn't catch that yet :-). > >> >> Outside of arch code it's only drivers/xen that currently uses that >> function. So I guess it's probably best to do a >> PFN_DOWN(virt_to_phys(...)) instead. Or look to fix x86 :) > > Mind sending a fix for that? Yeah, I'll have a go at Robin's suggestion of storing the struct page instead. Steve
