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From: Marc Zyngier <maz@kernel.org>
To: Saravana Kannan <saravanak@google.com>
Cc: Robin Murphy <robin.murphy@arm.com>, Qian Cai <qcai@redhat.com>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Len Brown <lenb@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Ard Biesheuvel <ardb@kernel.org>,
	Rob Herring <robh+dt@kernel.org>,
	Frank Rowand <frowand.list@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
	Grygorii Strashko <grygorii.strashko@ti.com>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	linux-efi <linux-efi@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
	Tomi Valkeinen <tomi.valkeinen@ti.com>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Android Kernel Team <kernel-team@android.com>,
	Linux Next Mailing List <linux-next@vger.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v2 16/17] driver core: Refactor fw_devlink feature
Date: Fri, 11 Dec 2020 18:03:15 +0000	[thread overview]
Message-ID: <813b3fbd80ad4dfee7ff8517d4829a1f@kernel.org> (raw)
In-Reply-To: <CAGETcx-MsNyWWT=s1H6hDK+=QvibBLQrT9rM51y5bkomV_+G6g@mail.gmail.com>

On 2020-12-11 17:51, Saravana Kannan wrote:
> On Fri, Dec 11, 2020 at 8:34 AM Robin Murphy <robin.murphy@arm.com> 
> wrote:
>> 
>> On 2020-12-11 14:11, Qian Cai wrote:
>> > On Fri, 2020-11-20 at 18:02 -0800, Saravana Kannan wrote:
>> >> The current implementation of fw_devlink is very inefficient because it
>> >> tries to get away without creating fwnode links in the name of saving
>> >> memory usage. Past attempts to optimize runtime at the cost of memory
>> >> usage were blocked with request for data showing that the optimization
>> >> made significant improvement for real world scenarios.
>> >>
>> >> We have those scenarios now. There have been several reports of boot
>> >> time increase in the order of seconds in this thread [1]. Several OEMs
>> >> and SoC manufacturers have also privately reported significant
>> >> (350-400ms) increase in boot time due to all the parsing done by
>> >> fw_devlink.
>> >>
>> >> So this patch uses all the setup done by the previous patches in this
>> >> series to refactor fw_devlink to be more efficient. Most of the code has
>> >> been moved out of firmware specific (DT mostly) code into driver core.
>> >>
>> >> This brings the following benefits:
>> >> - Instead of parsing the device tree multiple times during bootup,
>> >>    fw_devlink parses each fwnode node/property only once and creates
>> >>    fwnode links. The rest of the fw_devlink code then just looks at these
>> >>    fwnode links to do rest of the work.
>> >>
>> >> - Makes it much easier to debug probe issue due to fw_devlink in the
>> >>    future. fw_devlink=on blocks the probing of devices if they depend on
>> >>    a device that hasn't been added yet. With this refactor, it'll be very
>> >>    easy to tell what that device is because we now have a reference to
>> >>    the fwnode of the device.
>> >>
>> >> - Much easier to add fw_devlink support to ACPI and other firmware
>> >>    types. A refactor to move the common bits from DT specific code to
>> >>    driver core was in my TODO list as a prerequisite to adding ACPI
>> >>    support to fw_devlink. This series gets that done.
>> >>
>> >> [1] - https://lore.kernel.org/linux-omap/ea02f57e-871d-cd16-4418-c1da4bbc4696@ti.com/
>> >> Signed-off-by: Saravana Kannan <saravanak@google.com>
>> >> Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>> >> Tested-by: Grygorii Strashko <grygorii.strashko@ti.com>
>> >
>> > Reverting this commit and its dependency:
>> >
>> > 2d09e6eb4a6f driver core: Delete pointless parameter in fwnode_operations.add_links
>> >
>> > from today's linux-next fixed a boot crash on an arm64 Thunder X2 server.
>> 
>> Since the call stack implicates the platform-device-wrangling we do in
>> IORT code I took a quick look; AFAICS my guess would be it's blowing 
>> up
>> trying to walk a zeroed list head since "driver core: Add 
>> fwnode_init()"
>> missed acpi_alloc_fwnode_static().
> 
> Thanks Robin. I'm pretty sure this is the reason. I thought I fixed
> all ACPI cases, but clearly I missed this one. I'll send out a patch
> for this today. If you think there are any other places I missed
> please let me know. I'll try some git grep foo to see if I missed any
> other instances of fwnode ops being set.

Yup, that fixed it here (QDF2400).

Thanks,

         M.

diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 39263c6b52e1..2630c2e953f7 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -55,7 +55,7 @@ static inline struct fwnode_handle 
*acpi_alloc_fwnode_static(void)
  	if (!fwnode)
  		return NULL;

-	fwnode->ops = &acpi_static_fwnode_ops;
+	fwnode_init(fwnode, &acpi_static_fwnode_ops);

  	return fwnode;
  }



-- 
Jazz is not dead. It just smells funny...

  reply	other threads:[~2020-12-11 19:41 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-21  2:02 [PATCH v2 00/17] Refactor fw_devlink to significantly improve boot time Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 01/17] Revert "driver core: Avoid deferred probe due to fw_devlink_pause/resume()" Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 02/17] Revert "driver core: Rename dev_links_info.defer_sync to defer_hook" Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 03/17] Revert "driver core: Don't do deferred probe in parallel with kernel_init thread" Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 04/17] Revert "driver core: Remove check in driver_deferred_probe_force_trigger()" Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 05/17] Revert "of: platform: Batch fwnode parsing when adding all top level devices" Saravana Kannan
2020-12-07 22:18   ` Rob Herring
2020-11-21  2:02 ` [PATCH v2 06/17] Revert "driver core: fw_devlink: Add support for batching fwnode parsing" Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 07/17] driver core: Add fwnode_init() Saravana Kannan
2020-12-06  7:26   ` Leon Romanovsky
2020-12-07 19:25     ` Saravana Kannan
2020-12-07 19:53       ` Leon Romanovsky
2020-12-07 20:36         ` Saravana Kannan
2020-12-08  6:34           ` Leon Romanovsky
2020-12-07 22:20   ` Rob Herring
2020-11-21  2:02 ` [PATCH v2 08/17] driver core: Add fwnode link support Saravana Kannan
2020-12-06  7:48   ` Leon Romanovsky
2020-12-07 19:25     ` Saravana Kannan
2020-12-07 19:56       ` Leon Romanovsky
2020-12-07 22:21   ` Rob Herring
2020-11-21  2:02 ` [PATCH v2 09/17] driver core: Allow only unprobed consumers for SYNC_STATE_ONLY device links Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 10/17] device property: Add fwnode_is_ancestor_of() and fwnode_get_next_parent_dev() Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 11/17] driver core: Redefine the meaning of fwnode_operations.add_links() Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 12/17] driver core: Add fw_devlink_parse_fwtree() Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 13/17] driver core: Use device's fwnode to check if it is waiting for suppliers Saravana Kannan
2022-06-27 11:42   ` Abel Vesa
2022-06-27 22:30     ` Saravana Kannan
2022-06-28 15:24       ` Abel Vesa
2022-06-28 15:44         ` Abel Vesa
2022-06-28 15:55       ` Abel Vesa
2022-06-28 18:09         ` Saravana Kannan
2023-01-05 14:47           ` Dmitry Baryshkov
2020-11-21  2:02 ` [PATCH v2 14/17] of: property: Update implementation of add_links() to create fwnode links Saravana Kannan
2020-12-07 22:37   ` Rob Herring
2020-11-21  2:02 ` [PATCH v2 15/17] efi: " Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 16/17] driver core: Refactor fw_devlink feature Saravana Kannan
2020-11-23 16:00   ` [driver core] 95f755a4ef: will-it-scale.per_process_ops 2.2% improvement kernel test robot
2020-12-11 14:11   ` [PATCH v2 16/17] driver core: Refactor fw_devlink feature Qian Cai
2020-12-11 16:34     ` Robin Murphy
2020-12-11 17:51       ` Saravana Kannan
2020-12-11 18:03         ` Marc Zyngier [this message]
2020-12-11 18:20           ` Saravana Kannan
2020-12-11 19:07             ` Marc Zyngier
2020-12-11 22:29               ` Saravana Kannan
2020-12-29  3:34   ` Michael Walle
2021-01-05 19:00     ` Saravana Kannan
2021-01-05 21:03       ` Michael Walle
2021-01-06 23:29         ` Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 17/17] driver core: Delete pointless parameter in fwnode_operations.add_links Saravana Kannan
2020-12-07 22:38   ` Rob Herring
2020-11-24  8:29 ` [PATCH v2 00/17] Refactor fw_devlink to significantly improve boot time Tomi Valkeinen
2020-11-24 17:25   ` Saravana Kannan
2020-12-03 19:05   ` Saravana Kannan
2020-12-09 18:16 ` Greg Kroah-Hartman
2020-12-09 20:24   ` Saravana Kannan
2020-12-10  9:26     ` Greg Kroah-Hartman

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