Le 15/01/2015 10:11, Thomas Gleixner a écrit : > On Wed, 14 Jan 2015, Rob Herring wrote: >> On Wed, Jan 14, 2015 at 4:36 AM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote: >>> All attempts to work around that have resulted in horrible bandaids so >>> far. That's why I guided Boris to implement this dummy demultiplexing >>> mechanism. It solves the problem at hand nicely without adding nasty >>> hackarounds into the suspend/resume code and inflicting platform >>> knowledge on multi-platform device drivers. >> >> This change will break on old kernels with a new dtb. Would you be >> happy if a BIOS update required a new kernel? Fixing this for any >> platform requires a dtb update which may not be possible on some >> platforms. I don't have a problem with this breakage for 1 platform >> and the at91 guys may not care, but we'd ultimately be changing how >> all shared irqs are specified for all DT. Maybe we decide that this is >> how we want to describe things, but that needs much wider discussion >> and agreement. > > We do not change shared interrupts in any way. We provide an > alternative mechanism for braindead hardware. And if the at91 folks Let me add subtle details: "Old braindead hardware, with possibility to use alternative set of timers which doesn't have shared interrupt lines" ;-) > are fine with the DT change, then it's their decision. Nothing forces > this on everyone. Yes I do agree to change DT. >>> If you have a proper solution for the problem at hand which >>> >>> - avoids the demux dummy >>> >>> - works straight forward with suspend/resume/wakeup >>> >>> - does not add horrible new APIs >>> >>> - does not add conditionals to the interrupt hotpath >>> >>> - does not inflict platform knowledge about interrupt chip details >>> on drivers >>> >>> then I'm happy to take it. >>> >>> But as long as you can't come up with anything sane, the demux dummy >>> is the best solution for this problem we've seen so far. >> >> What if during suspend you move all actions w/o IRQF_NO_SUSPEND to a >> suspended action list? This would leave only the actions with >> IRQF_NO_SUSPEND set in the active action list. The cost would be a >> pointer in irq_desc and moving the actions during suspend and resume. > > That's exactly what we want NOT. Because it prevents us to do proper > sanity checks for IRQF_NO_SUSPEND. We've been there and I rejected it > for that very reason. > >> There are probably ways to do this demux irqchip without a DT change. > > What's the problem with a DT change for a single platform, if the > maintainers are willing to take it and deal with the fallout? > > And in case of AT91 the new kernel will simply work with the old DT > and just emit the same warning vs. the IRQF_NO_SUSPEND mismatch. Older > kernels won't work with a new DT, but that's about it. > > Aside of that, I'm quite amused about your DT update worries. DTs > break with every kernel version on very popular platforms in very > weird and subtle ways. DT on AT91 is a Work In Progress (for 3.5 years) and the facts have told us that DT updates were absolutely necessary. So, for now, I agree to change DT as far as AT91 is concerned. Bye, -- Nicolas Ferre -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
