On Thu, Oct 1, 2020 at 12:43 PM Grygorii Strashko
<grygorii.strashko@xxxxxx> wrote:
>
>
>
> On 01/10/2020 21:24, Saravana Kannan wrote:
> > On Thu, Oct 1, 2020 at 5:56 AM Grygorii Strashko
> > <grygorii.strashko@xxxxxx> wrote:
> >>
> >>
> >>
> >> On 01/10/2020 11:22, Laurent Pinchart wrote:
> >>> Hi Tony,
> >>>
> >>> On Thu, Oct 01, 2020 at 11:17:48AM +0300, Tony Lindgren wrote:
> >>>> * Tony Lindgren <tony@xxxxxxxxxxx> [201001 07:53]:
> >>>>> * Peter Ujfalusi <peter.ujfalusi@xxxxxx> [200930 12:41]:
> >>>>>> Fwiw on my beagle x15
> >>>>>>
> >>>>>> v5.8
> >>>>>> [ 9.908787] Run /sbin/init as init process
> >>>>>>
> >>>>>> v5.9-rc7
> >>>>>> [ 15.085373] Run /sbin/init as init process
> >>>>>>
> >>>>>>
> >>>>>> It appears to be 'fixed' in next-20200928: the board does not even boot.
> >>>>>
> >>>>> Yeah so it seems :(
> >>>>>
> >>>>>> next-20200928 on omap5
> >>>>>> [ 9.936806] Run /sbin/init as init process
> >>>>>>
> >>>>>>
> >>>>>> -rc7 spends most of it's time:
> >>>>>> [ 7.635530] Micrel KSZ9031 Gigabit PHY 48485000.mdio:01: attached PHY driver [Micrel KSZ9031 Gigabit PHY] (mii_bus:phy_addr=48485000.mdio:01, irq=POLL)
> >>>>>> [ 14.956671] cpsw 48484000.ethernet eth0: Link is Up - 1Gbps/Full - flow control off
> >>>>>> [ 15.005211] IP-Config: Complete:
> >>>>>
> >>>>> Booting with initcall_debug I see this with current Linux next:
> >>>>>
> >>>>> ...
> >>>>> [ 1.697313] cpuidle: using governor menu
> >>>>> [ 1.701353] initcall init_menu+0x0/0xc returned 0 after 0 usecs
> >>>>> [ 1.707458] calling gpmc_init+0x0/0x10 @ 1
> >>>>> [ 1.711784] initcall gpmc_init+0x0/0x10 returned 0 after 0 usecs
> >>>>> [ 1.717974] calling omap3_l3_init+0x0/0x10 @ 1
> >>>>> [ 1.722653] initcall omap3_l3_init+0x0/0x10 returned 0 after 0 usecs
> >>>>> [ 1.729201] calling omap_l3_init+0x0/0x10 @ 1
> >>>>> [ 1.733791] initcall omap_l3_init+0x0/0x10 returned 0 after 0 usecs
> >>>>> [ 1.740314] calling gate_vma_init+0x0/0x70 @ 1
> >>>>> [ 1.744976] initcall gate_vma_init+0x0/0x70 returned 0 after 0 usecs
> >>>>> [ 1.751522] calling customize_machine+0x0/0x30 @ 1
> >>>>> [ 3.823114] initcall customize_machine+0x0/0x30 returned 0 after 2011718 usecs
> >>>>> [ 3.830566] calling init_atags_procfs+0x0/0xec @ 1
> >>>>> [ 3.835583] No ATAGs?
> >>>>
> >>>> And the long time above with customize_machine() ends up being
> >>>> pdata_quirks_init() calling of_platform_populate().
> >>>
> >>> That's what the delay is for me (I think I've reported that initially).
> >>>
> >>>>> Laurent & Tomi, care to check what you guys see in the slow booting case
> >>>>> after booting with initcall_debug?
> >>>>
> >>>> But maybe the long delay is something else for you guys so please check.
> >>>
> >>
> >> It's all devlink :( Looks like sometimes, improvements (PM) could became so complicated
> >> that time required to execute such algorithms may completely eliminate all expected benefits.
> >> Will not be surprised if PM consumption also increased instead of decreasing in some cases.
> >>
> >> not sure if it's 100% correct, but below diff reduces boot time
> >> from 7.6sec to 3.7sec :P
> >>
> >> before:
> >> [ 0.053870] cpuidle: using governor menu
> >> [ 2.505971] No ATAGs?
> >> ...
> >> [ 7.562317] Freeing unused kernel memory: 1024K
> >>
> >> after:
> >> [ 0.053800] cpuidle: using governor menu
> >> [ 0.136853] No ATAGs?
> >> [ 3.716218] devtmpfs: mounted
> >> [ 3.719628] Freeing unused kernel memory: 1024K
> >> [ 3.724266] Run /sbin/init as init process
> >>
> >> ----
> >> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> >> index 071f04da32c8..e0cc37ed46ca 100644
> >> --- a/drivers/of/platform.c
> >> +++ b/drivers/of/platform.c
> >> @@ -481,6 +481,7 @@ int of_platform_populate(struct device_node *root,
> >> pr_debug(" starting at: %pOF\n", root);
> >>
> >> device_links_supplier_sync_state_pause();
> >> + fw_devlink_pause();
> >> for_each_child_of_node(root, child) {
> >> rc = of_platform_bus_create(child, matches, lookup, parent, true);
> >> if (rc) {
> >> @@ -488,6 +489,7 @@ int of_platform_populate(struct device_node *root,
> >> break;
> >> }
> >> }
> >> + fw_devlink_resume();
> >> device_links_supplier_sync_state_resume();
> >>
> >> of_node_set_flag(root, OF_POPULATED_BUS);
> >> @@ -538,9 +540,7 @@ static int __init of_platform_default_populate_init(void)
> >> }
> >>
> >> /* Populate everything else. */
> >> - fw_devlink_pause();
> >> of_platform_default_populate(NULL, NULL, NULL);
> >> - fw_devlink_resume();
> >
> > Your analysis is right, but this change is not safe. You'll get an
> > unlocked linked list trampling if you call it outside of where it's
> > called now. That's explicitly why I didn't do it the way this patch
> > does it.
> >
> > To explain more, if you call fw_devlink_pause/resume() inside
> > of_platform_populate() you can end up calling it in the context of
> > another device's probe function. When a device's probe function is
> > called, a has a bunch of other locks held and you'll cause a deadlock.
> > To avoid that, I had to use defer_fw_devlink_lock to manage the list
> > used by fw_devlink_pause/resume().
> >
> > I'll add more details later. But yeah, this patch isn't safe as is.
>
> I assume you going to fix it your way, right?
I'll be glad to fix this if I find a way out. But currently, there's
no "my way" for a generic fix to use inside of_platform_populate().
However...
> Just FYI. On ARM main DT population path is:
>
> arch_initcall(customize_machine)
> machine_desc->init_machine();
> of_platform_default_populate();
> -- or --
> of_platform_populate();
>
> the of_platform_default_populate_init() called later due to make/linker dependencies.
>
> As result, existing pause/resume optimizations don't fully working.
We can just add this optimization around all the other places the top
level addition of DT devices is done. I wasn't aware of (more like
forgot) the init_machine() path.
Can you give the call path in your case? Just to make it a bit easier for me.
Thanks,
Saravana
