From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Saravana Kannan <saravanak@google.com>
Cc: Rob Herring <robh+dt@kernel.org>,
Frank Rowand <frowand.list@gmail.com>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Grygorii Strashko <grygorii.strashko@ti.com>,
linux-omap <linux-omap@vger.kernel.org>,
"open list:THERMAL" <linux-pm@vger.kernel.org>,
Peter Ujfalusi <peter.ujfalusi@ti.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Tomi Valkeinen <tomi.valkeinen@ti.com>,
Tony Lindgren <tony@atomide.com>,
Ulf Hansson <ulf.hansson@linaro.org>,
Android Kernel Team <kernel-team@android.com>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1] of: platform: Batch fwnode parsing in the init_machine() path
Date: Fri, 2 Oct 2020 21:27:12 +0300 [thread overview]
Message-ID: <20201002182712.GF3933@pendragon.ideasonboard.com> (raw)
In-Reply-To: <CAGETcx-7nJaU6pDo_KL-nKmCaxv57C5aaXq-pvo4XiN=N0K5Jg@mail.gmail.com>
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@kernel.org> wrote:
> > > > On Thu, Oct 1, 2020 at 5:59 PM Saravana Kannan <saravanak@google.com> 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@ti.com>
> > > > > Signed-off-by: Saravana Kannan <saravanak@google.com>
> > > > > ---
> > > > > 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.
--
Regards,
Laurent Pinchart
next prev parent reply other threads:[~2020-10-02 18:27 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAGETcx8owDP_Bu4oNCyHEsME8XpKygxghm8+yNc2RyMA4wyjCA@mail.gmail.com>
2020-10-01 22:59 ` [PATCH v1] of: platform: Batch fwnode parsing in the init_machine() path Saravana Kannan
2020-10-01 23:19 ` Laurent Pinchart
2020-10-02 11:40 ` Grygorii Strashko
2020-10-02 15:03 ` Grygorii Strashko
2020-10-02 17:48 ` Saravana Kannan
2020-10-02 18:11 ` Grygorii Strashko
2020-10-02 14:07 ` Rob Herring
2020-10-02 17:51 ` Saravana Kannan
2020-10-02 17:54 ` Laurent Pinchart
2020-10-02 17:58 ` Saravana Kannan
2020-10-02 18:27 ` Laurent Pinchart [this message]
2020-10-02 18:35 ` Grygorii Strashko
2020-10-02 19:56 ` Saravana Kannan
2020-10-03 0:13 ` Laurent Pinchart
2020-10-27 3:29 ` Saravana Kannan
2020-10-28 7:34 ` Tomi Valkeinen
2020-10-02 20:29 ` Rob Herring
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