Am Montag, 22. Dezember 2014, 11:31:48 schrieb Doug Anderson: > We've been seeing some crashes at resume time on rk3288-based systems. > On some machines they simply never wake up from suspend. Symptoms > include: > > - System clearly got to sleep OK. Power consumption is low, the PWM > for the PWM regulator has stopped, and the "global_pwroff" output > shows that the system is down. > > - When system tries to wake up power consumption goes up. > > - No kernel resume code (which was left in PMU SRAM) ran. We added > some basic logging to this code (write to a location in SRAM right > at resume time) and didn't see the logging run. > > It appears that we can fix the problem by slowing down APLL before we > suspend. On the system I tested things seemed reliable if I disabled > 1.8GHz and 1.7GHz. The Mask ROM itself tries to slow things down > (which is why PLLs are in slow mode by the time we get to the kernel), > but apparently it is crashing before it even gets there. > > We'll be super paranoid and not just go down to 1.6GHz but we'll match > what the Mask ROM seems to be doing and go into slow mode. We'll also > be safe and put all PLLs (not just APLL) into slow mode (well, except > DPLL which is needed for SDRAM). We'll even put NPLL into slow mode > which the Mask ROM didn't do (not that it's used for much important > stuff at early resume time). > > Note that the old Rockchip reference code did something just like > this, though they jammed it into pm.c instead of putting it in the > syscore ops of the clock driver. > > Signed-off-by: Doug Anderson <dianders at chromium.org> applied to my clk branch for 3.20 As I already talked about with Doug on IRC (last year), I see this as a sort- of stop-gap solution till we know the suspend requirements of the older/other Rockchip SoCs that do suspend slightly different and can generalize the whole clk suspend handling at this point. Heiko
