On 01.10.14 16:33, Geert Uytterhoeven wrote: > Hi Alex, > > On Wed, Oct 1, 2014 at 3:27 PM, Alexander Graf <ag...@suse.de> wrote: >> The generic Linux framework to power off the machine is a function pointer >> called pm_power_off. The trick about this pointer is that device drivers can >> potentially implement it rather than board files. >> >> Today on PowerPC we set pm_power_off to invoke our generic full machine power >> off logic which then calls ppc_md.power_off to invoke machine specific power >> off. >> >> However, when we want to add a power off GPIO via the "gpio-poweroff" driver, >> this card house falls apart. That driver only registers itself if >> pm_power_off >> is NULL to ensure it doesn't override board specific logic. However, since we >> always set pm_power_off to the generic power off logic (which will just not >> power off the machine if no ppc_md.power_off call is implemented), we can't >> implement power off via the generic GPIO power off driver. >> >> To fix this up, let's get rid of the ppc_md.power_off logic and just always >> use >> pm_power_off as was intended. Then individual drivers such as the GPIO power >> off >> driver can implement power off logic via that function pointer. >> >> With this patch set applied and a few patches on top of QEMU that implement a >> power off GPIO on the virt e500 machine, I can successfully turn off my >> virtual >> machine after halt. > > This is touching the same area as last night's > "[RFC PATCH 00/16] kernel: Add support for poweroff handler call chain" > https://lkml.org/lkml/2014/9/30/575
I agree, and I think your patch set is walking into a reasonable direction. However, I really think it should convert all users of pm_power_off - at which point you'll probably get to the same conclusion that ppc_md.power_off is a bad idea :). So in a way, this patch set is semantically a prerequisite to the full conversion you'd probably like to do :). Also, in your cover letter you describe that some methods power off the CPU power while others power off the system power. How do you distinguish between them with a call chain? You probably won't get around to trigger the system power off callback after the CPU power off callback ran ;). Alex _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
