Re: [PATCH v1] of: platform: Batch fwnode parsing in the init_machine() path

[Grygorii Strashko]

hi Saravana,

On 02/10/2020 21:27, Laurent Pinchart wrote:
> Hi Saravana,
>
> On Fri, Oct 02, 2020 at 10:58:55AM -0700, Saravana Kannan wrote:
> > On Fri, Oct 2, 2020 at 10:55 AM Laurent Pinchart wrote:
> > > On Fri, Oct 02, 2020 at 10:51:51AM -0700, Saravana Kannan wrote:
> > > > On Fri, Oct 2, 2020 at 7:08 AM Rob Herring <robh+dt@xxxxxxxxxx> wrote:
> > > > > On Thu, Oct 1, 2020 at 5:59 PM Saravana Kannan <saravanak@xxxxxxxxxx> wrote:
> > > > > > When commit 93d2e4322aa7 ("of: platform: Batch fwnode parsing when
> > > > > > adding all top level devices") optimized the fwnode parsing when all top
> > > > > > level devices are added, it missed out optimizing this for platform
> > > > > > where the top level devices are added through the init_machine() path.
> > > > > >
> > > > > > This commit does the optimization for all paths by simply moving the
> > > > > > fw_devlink_pause/resume() inside of_platform_default_populate().
> > > > > >
> > > > > > Reported-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
> > > > > > Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx>
> > > > > > ---
> > > > > >   drivers/of/platform.c | 19 +++++++++++++++----
> > > > > >   1 file changed, 15 insertions(+), 4 deletions(-)
> > > > > >
> > > > > > diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> > > > > > index 071f04da32c8..79972e49b539 100644
> > > > > > --- a/drivers/of/platform.c
> > > > > > +++ b/drivers/of/platform.c
> > > > > > @@ -501,8 +501,21 @@ int of_platform_default_populate(struct device_node *root,
> > > > > >                                   const struct of_dev_auxdata *lookup,
> > > > > >                                   struct device *parent)
> > > > > >   {
> > > > > > -       return of_platform_populate(root, of_default_bus_match_table, lookup,
> > > > > > -                                   parent);
> > > > > > +       int ret;
> > > > > > +
> > > > > > +       /*
> > > > > > +        * fw_devlink_pause/resume() are only safe to be called around top
> > > > > > +        * level device addition due to locking constraints.
> > > > > > +        */
> > > > > > +       if (!root)
> > > > > > +               fw_devlink_pause();
> > > > > > +
> > > > > > +       ret = of_platform_populate(root, of_default_bus_match_table, lookup,
> > > > > > +                                  parent);
> > > > >
> > > > > of_platform_default_populate() vs. of_platform_populate() is just a
> > > > > different match table. I don't think the behavior should otherwise be
> > > > > different.
> > > > >
> > > > > There's also of_platform_probe() which has slightly different matching
> > > > > behavior. It should not behave differently either with respect to
> > > > > devlinks.
> > > >
> > > > So I'm trying to do this only when the top level devices are added for
> > > > the first time. of_platform_default_populate() seems to be the most
> > > > common path. For other cases, I think we just need to call
> > > > fw_devlink_pause/resume() wherever the top level devices are added for
> > > > the first time. As I said in the other email, we can't add
> > > > fw_devlink_pause/resume() by default to of_platform_populate().
> > > >
> > > > Do you have other ideas for achieving "call fw_devlink_pause/resume()
> > > > only when top level devices are added for the first time"?
> > >
> > > I'm not an expert in this domain, but before investigating it, would you
> > > be able to share a hack patch that implements this (in the most simple
> > > way) to check if it actually fixes the delays I experience on my system
> > > ?
> >
> > So I take it the patch I sent out didn't work for you? Can you tell me
> > what machine/DT you are using?
>
> I've replied to the patch:
>
> Based on v5.9-rc5, before the patch:
>
> [    0.652887] cpuidle: using governor menu
> [   12.349476] No ATAGs?
>
> After the patch:
>
> [    0.650460] cpuidle: using governor menu
> [   12.262101] No ATAGs?
>
> I'm using an AM57xx EVM, whose DT is not upstream, but it's essentially
> a am57xx-beagle-x15-revb1.dts (it includes that DTS) with a few
> additional nodes for GPIO keys, LCD panel, backlight and touchscreen.

hope you are receiving my mails as I've provided you with all required information already [1]

with below diff:
[    4.177231] Freeing unused kernel memory: 1024K
[    4.181892] Run /sbin/init as init process

The best time with [2] is
[    3.100483] Run /sbin/init as init process

Still 1 sec lose.

Pls understand an issue - requirements here are like 500ms boot with can, Ethernet, camera and display on ;(

[1] https://lore.kernel.org/patchwork/patch/1316134/#1511276
[2] https://lore.kernel.org/patchwork/patch/1316134/#1511435

diff --git a/arch/arm/mach-omap2/pdata-quirks.c b/arch/arm/mach-omap2/pdata-quirks.c
index 2a4fe3e68b82..ac1ab8928190 100644
--- a/arch/arm/mach-omap2/pdata-quirks.c
+++ b/arch/arm/mach-omap2/pdata-quirks.c
@@ -591,7 +591,9 @@ void __init pdata_quirks_init(const struct of_device_id *omap_dt_match_table)
        if (of_machine_is_compatible("ti,omap3"))
                omap3_mcbsp_init();
        pdata_quirks_check(auxdata_quirks);
+       fw_devlink_pause();
        of_platform_populate(NULL, omap_dt_match_table,
                             omap_auxdata_lookup, NULL);
+       fw_devlink_resume();
        pdata_quirks_check(pdata_quirks);
 }


--
Best regards,
grygorii