On Tue, 2013-08-06 at 01:00 +0800, Stephen Warren wrote: > On 08/05/2013 02:02 AM, Joseph Lo wrote: > > On Sat, 2013-08-03 at 04:32 +0800, Stephen Warren wrote: > >> On 08/02/2013 02:09 AM, Joseph Lo wrote: > >>> On Tue, 2013-07-30 at 06:51 +0800, Stephen Warren wrote: > >>>> On 07/26/2013 03:15 AM, Joseph Lo wrote: > >>>>> When the system suspends to LP1, the clock of the CPU would be switched to > >>>>> CLK_M (12MHz Oscillator) during suspend/resume flow. The clock driver > >>>>> needs to restore the clock of CPU after LP1 resume. > >>>> [snip] > >>>> Why don't Tegra20/30 need a similar change? > >>> > >>> For Tegra20/30, the same code had been implemented in the suspend/resume > >>> function of tegra_cpu_car_ops. It restores the CPU clock ASAP when CPU > >>> resume from a suspend state to get quick performance I believe. > >>> > >>> For Tegra114, the resume performance is cool (although we can't see it > >>> in upstream kernel now, it still need some other functions.). We can > >>> implement all the clock related suspend/resume function in the clock > >>> driver. > >> > >> OK, I do see something similar in tegra20/30_cpu_clock_suspend/resume. > >> Why can't this new code be part of the equivalent functions; does the > >> Tegra114 suspend/resume code in mach-tegra/ not call > >> tegra_cpu_car_ops.suspend/resume() in the same way it does on Tegra20/30? > > > > One of the main reasons is due to DFLL clock. The CPU clock of Tegra114 > > is going to switch to DFLL to a get higher clock rate. But it depends > > some other HW (i.e. I2C), we can't resume it so early when the CPU just > > resume like we did in tegra_cpu_car_ops.suspend/resume for Tegra20/30. > > Is there a guarantee that the syscore_ops are run after the call to > tegar_cpu_car_ops.resume() would be? Perhaps the mach-tegra/ code should > simply call tegra_cpu_car_ops.resume() later on Tegra114 than it does on > earlier chips, so it's run at a suitable time? Yes, the tegra_cpu_car_ops.suspend/resume() is hooked to suspend_cpu_complex()/resuem_cpu_complex() that in the "pm.c" file. It would be the final/first function be invoked when system suspend/resume. -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
