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. > > > 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?
