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 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 :-).
