On Wed, Apr 27, 2016 at 10:57:21AM +0800, Dong Aisheng wrote: > On Wed, Apr 27, 2016 at 9:58 AM, Shawn Guo <shawn...@kernel.org> wrote: > > On Tue, Apr 26, 2016 at 07:27:03PM +0800, Dong Aisheng wrote: > >> Shawn, > >> What's your suggestion? > > > > I think this needs more discussion, and I just dropped Stefan's patch > > from my tree. > > > > We need to firstly understand why this is happening. The .prepare hook > > is defined to be non-atomic context, and so that we call sleep function > > in there. We did everything right. Why are we getting the warning? If > > I'm correct, this warning only happens on i.MX7D. Why is that? > > > > Why Stefan's patch works (checking irqs_disabled()) is because during kernel > time init, the irq is still not enabled. It fixes the issue indirectly. > See: > asmlinkage __visible void __init start_kernel(void) > { > /* > * Set up the scheduler prior starting any interrupts (such as the > * timer interrupt). Full topology setup happens at smp_init() > * time - but meanwhile we still have a functioning scheduler. > */ > sched_init(); > ............. > time_init(); > .............. > WARN(!irqs_disabled(), "Interrupts were enabled early\n"); > early_boot_irqs_disabled = false; > local_irq_enable(); > } > > The issue can only happen when PLL enable causes a schedule during > imx_clock_init(). > Not all PLL has this issue. > The issue happens on MX7D pll_audio_main_clk/pll_video_main_clk > which requires more delay time and cause usleep. > Because clk framework does not support MX7D clock types (operation requires > parents on), we simply enable all clocks in imx7d_clocks_init(). > > If apply my this patch series: > https://lkml.org/lkml/2016/4/20/199 > The issue can also be gone.
Thanks for the info. It sounds like that we are fixing the problem in the wrong place, i.e. clk_pllv3_prepare(). The function does nothing wrong, since the .prepare hook is defined to be one that can sleep. If we see sleep warning in a context calling clk_prepare(), that probably means we shouldn't make the function call from that context. Shawn