From: Saravana Kannan <saravanak@google.com>
To: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Android Kernel Team <kernel-team@android.com>,
LKML <linux-kernel@vger.kernel.org>,
Jisheng Zhang <Jisheng.Zhang@synaptics.com>,
Kevin Hilman <khilman@baylibre.com>,
John Stultz <john.stultz@linaro.org>,
Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
Marc Zyngier <maz@kernel.org>,
Linux Samsung SOC <linux-samsung-soc@vger.kernel.org>,
Krzysztof Kozlowski <krzk@kernel.org>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Subject: Re: [PATCH v1 5/5] driver core: Set fw_devlink=on by default
Date: Mon, 11 Jan 2021 13:47:16 -0800 [thread overview]
Message-ID: <CAGETcx8-1YzF2Br0sszJROLAWo3DSm27K071Md9wY5SOwUeLdw@mail.gmail.com> (raw)
In-Reply-To: <2556a69b-5da5-bf80-e051-df2d02fbc40f@samsung.com>
On Mon, Jan 11, 2021 at 6:18 AM Marek Szyprowski
<m.szyprowski@samsung.com> wrote:
>
> On 11.01.2021 12:12, Marek Szyprowski wrote:
> > On 18.12.2020 04:17, Saravana Kannan wrote:
> >> Cyclic dependencies in some firmware was one of the last remaining
> >> reasons fw_devlink=on couldn't be set by default. Now that cyclic
> >> dependencies don't block probing, set fw_devlink=on by default.
> >>
> >> Setting fw_devlink=on by default brings a bunch of benefits (currently,
> >> only for systems with device tree firmware):
> >> * Significantly cuts down deferred probes.
> >> * Device probe is effectively attempted in graph order.
> >> * Makes it much easier to load drivers as modules without having to
> >> worry about functional dependencies between modules (depmod is still
> >> needed for symbol dependencies).
> >>
> >> If this patch prevents some devices from probing, it's very likely due
> >> to the system having one or more device drivers that "probe"/set up a
> >> device (DT node with compatible property) without creating a struct
> >> device for it. If we hit such cases, the device drivers need to be
> >> fixed so that they populate struct devices and probe them like normal
> >> device drivers so that the driver core is aware of the devices and their
> >> status. See [1] for an example of such a case.
> >>
> >> [1] -
> >> https://lore.kernel.org/lkml/CAGETcx9PiX==mLxB9PO8Myyk6u2vhPVwTMsA5NkD-ywH5xhusw@mail.gmail.com/
> >> Signed-off-by: Saravana Kannan <saravanak@google.com>
> >
> > This patch landed recently in linux next-20210111 as commit
> > e590474768f1 ("driver core: Set fw_devlink=on by default"). Sadly it
> > breaks Exynos IOMMU operation, what causes lots of devices being
> > deferred and not probed at all. I've briefly checked and noticed that
> > exynos_sysmmu_probe() is never called after this patch. This is really
> > strange for me, as the SYSMMU controllers on Exynos platform are
> > regular platform devices registered by the OF code. The driver code is
> > here: drivers/iommu/exynos-iommu.c, example dts:
> > arch/arm/boot/dts/exynos3250.dtsi (compatible = "samsung,exynos-sysmmu").
>
> Okay, I found the source of this problem. It is caused by Exynos power
> domain driver, which is not platform driver yet. I will post a patch,
> which converts it to the platform driver.
Thanks Marek! Hopefully the debug logs I added were sufficient to
figure out the reason.
-Saravana
next prev parent reply other threads:[~2021-01-11 21:48 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-18 3:16 [PATCH v1 0/5] Enable fw_devlink=on by default Saravana Kannan
2020-12-18 3:16 ` [PATCH v1 1/5] driver core: Add debug logs for device link related probe deferrals Saravana Kannan
2020-12-18 3:17 ` [PATCH v1 2/5] driver core: Add device link support for INFERRED flag Saravana Kannan
2020-12-18 3:17 ` [PATCH v1 3/5] driver core: Have fw_devlink use DL_FLAG_INFERRED Saravana Kannan
2020-12-18 3:17 ` [PATCH v1 4/5] driver core: Handle cycles in device links created by fw_devlink Saravana Kannan
2020-12-18 6:39 ` kernel test robot
2020-12-18 6:39 ` [RFC PATCH] driver core: fw_devlink_relax_cycle() can be static kernel test robot
2020-12-18 6:48 ` [PATCH v1 4/5] driver core: Handle cycles in device links created by fw_devlink kernel test robot
2020-12-18 7:12 ` kernel test robot
2020-12-18 3:17 ` [PATCH v1 5/5] driver core: Set fw_devlink=on by default Saravana Kannan
[not found] ` <CGME20210111111245eucas1p15acde7ecc2ca7f7782beb8ed74c72022@eucas1p1.samsung.com>
2021-01-11 11:12 ` Marek Szyprowski
[not found] ` <CGME20210111141814eucas1p1f388df07b789693a999042b27f0d8c2a@eucas1p1.samsung.com>
2021-01-11 14:18 ` Marek Szyprowski
2021-01-11 21:47 ` Saravana Kannan [this message]
2021-01-12 7:11 ` Marek Szyprowski
2021-01-12 20:51 ` Saravana Kannan
2021-01-13 7:04 ` Marek Szyprowski
2021-01-13 19:23 ` Saravana Kannan
2021-01-14 7:36 ` Marek Szyprowski
2021-01-14 18:08 ` Saravana Kannan
2021-01-18 17:43 ` Geert Uytterhoeven
2021-01-17 23:01 ` Michael Walle
2021-01-18 21:01 ` Saravana Kannan
2021-01-19 10:41 ` Michael Walle
2021-01-20 0:00 ` Saravana Kannan
2021-01-18 17:39 ` Geert Uytterhoeven
2021-01-18 17:59 ` Marc Zyngier
2021-01-18 19:16 ` Geert Uytterhoeven
2021-01-18 19:30 ` Marc Zyngier
2021-01-18 21:18 ` Saravana Kannan
2021-01-19 9:05 ` Geert Uytterhoeven
2021-01-19 18:08 ` Saravana Kannan
2021-01-19 21:50 ` Saravana Kannan
2021-01-20 9:40 ` Geert Uytterhoeven
2021-01-20 14:26 ` Geert Uytterhoeven
2021-01-20 17:22 ` Saravana Kannan
2021-01-21 16:04 ` Geert Uytterhoeven
2021-01-25 23:30 ` Saravana Kannan
2021-01-26 8:25 ` Geert Uytterhoeven
2021-01-20 9:11 ` Geert Uytterhoeven
2021-01-21 8:22 ` [TEST PATCH v1] driver: core: Make fw_devlink=on more forgiving Saravana Kannan
2021-01-21 8:27 ` Saravana Kannan
2021-01-21 10:37 ` Geert Uytterhoeven
2021-01-22 1:07 ` Saravana Kannan
2021-01-21 10:33 ` Marek Szyprowski
2021-01-25 17:05 ` [PATCH v1 5/5] driver core: Set fw_devlink=on by default Tudor.Ambarus
2021-01-25 18:16 ` Saravana Kannan
2021-01-28 10:59 ` Tudor.Ambarus
2021-01-28 17:04 ` Saravana Kannan
2021-02-10 5:54 ` Guenter Roeck
2021-02-10 8:20 ` Saravana Kannan
2021-02-10 15:10 ` Guenter Roeck
2021-02-10 20:52 ` Saravana Kannan
2021-02-10 21:21 ` Guenter Roeck
2021-02-17 2:39 ` Saravana Kannan
2021-02-17 3:05 ` Guenter Roeck
2021-02-17 3:13 ` Saravana Kannan
2020-12-18 21:11 ` [PATCH v1 0/5] Enable " Saravana Kannan
2020-12-21 8:18 ` Jisheng Zhang
[not found] ` <CAHp75VfqL1QuvjCZ7p23e_2qhY3DUgVNaS--Uk1mEoEHsD8GBA@mail.gmail.com>
2021-01-14 16:49 ` Saravana Kannan
2020-12-21 9:48 ` Rafael J. Wysocki
2021-01-07 20:05 ` Greg Kroah-Hartman
2021-01-07 21:53 ` Saravana Kannan
2021-01-13 11:11 ` Marc Zyngier
2021-01-13 15:27 ` Jon Hunter
2021-01-13 21:29 ` Saravana Kannan
2021-01-14 11:34 ` Jon Hunter
2021-01-14 16:40 ` Saravana Kannan
2021-01-14 16:47 ` Jon Hunter
2021-01-14 16:52 ` Saravana Kannan
2021-01-14 18:55 ` Jon Hunter
2021-01-14 21:50 ` Saravana Kannan
2021-01-15 16:12 ` Jon Hunter
2021-01-15 17:44 ` Saravana Kannan
2021-01-13 20:56 ` Saravana Kannan
2021-01-13 11:30 ` Jon Hunter
2021-01-13 21:26 ` Saravana Kannan
2021-01-14 16:11 ` Jon Hunter
2021-01-14 16:47 ` Saravana Kannan
2021-01-14 16:56 ` Jon Hunter
2021-01-28 15:03 ` Jon Hunter
2021-01-28 17:27 ` Saravana Kannan
2021-02-11 0:02 ` Saravana Kannan
2021-02-11 15:03 ` Rafael J. Wysocki
2021-02-11 17:14 ` Saravana Kannan
2021-02-11 17:48 ` Rafael J. Wysocki
2021-02-12 3:04 ` Saravana Kannan
2021-01-13 11:44 ` Nicolas Saenz Julienne
2021-01-13 11:48 ` Marc Zyngier
2021-01-13 21:27 ` Saravana Kannan
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