lkml.org 
[lkml]   [2023]   [Feb]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v3 09/12] of: property: Simplify of_link_to_phandle()
Hi Saravana,

On Wed, Feb 8, 2023 at 3:08 AM Saravana Kannan <saravanak@google.com> wrote:
> On Tue, Feb 7, 2023 at 12:57 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > On Tue, Feb 7, 2023 at 2:42 AM Saravana Kannan <saravanak@google.com> wrote:
> > > The driver core now:
> > > - Has the parent device of a supplier pick up the consumers if the
> > > supplier never has a device created for it.
> > > - Ignores a supplier if the supplier has no parent device and will never
> > > be probed by a driver
> > >
> > > And already prevents creating a device link with the consumer as a
> > > supplier of a parent.
> > >
> > > So, we no longer need to find the "compatible" node of the supplier or
> > > do any other checks in of_link_to_phandle(). We simply need to make sure
> > > that the supplier is available in DT.
> > >
> > > Signed-off-by: Saravana Kannan <saravanak@google.com>
> >
> > Thanks for your patch!
> >
> > This patch introduces a regression when dynamically loading DT overlays.
> > Unfortunately this happens when using the out-of-tree OF configfs,
> > which is not supported upstream. Still, there may be (obscure)
> > in-tree users.
> >
> > When loading a DT overlay[1] to enable an SPI controller, and
> > instantiate a connected SPI EEPROM:
> >
> > $ overlay add 25lc040
> > OF: overlay: WARNING: memory leak will occur if overlay removed,
> > property: /keys/status
> > OF: overlay: WARNING: memory leak will occur if overlay removed,
> > property: /soc/spi@e6e90000/pinctrl-0
> > OF: overlay: WARNING: memory leak will occur if overlay removed,
> > property: /soc/spi@e6e90000/pinctrl-names
> > OF: overlay: WARNING: memory leak will occur if overlay removed,
> > property: /soc/spi@e6e90000/cs-gpios
> > OF: overlay: WARNING: memory leak will occur if overlay removed,
> > property: /soc/spi@e6e90000/status
> > OF: overlay: WARNING: memory leak will occur if overlay removed,
> > property: /__symbols__/msiof0_pins
> >
> > The SPI controller and the SPI EEPROM are no longer instantiated.
> >
> > # cat /sys/kernel/debug/devices_deferred
> > e6e90000.spi platform: wait for supplier msiof0
> >
> > Let's remove the overlay again:
> >
> > $ overlay rm 25lc040
> > input: keys as /devices/platform/keys/input/input1
> >
> > And retry:
> >
> > $ overlay add 25lc040
> > OF: overlay: WARNING: memory leak will occur if overlay removed,
> > property: /keys/status
> > OF: overlay: WARNING: memory leak will occur if overlay removed,
> > property: /soc/spi@e6e90000/pinctrl-0
> > OF: overlay: WARNING: memory leak will occur if overlay removed,
> > property: /soc/spi@e6e90000/pinctrl-names
> > OF: overlay: WARNING: memory leak will occur if overlay removed,
> > property: /soc/spi@e6e90000/cs-gpios
> > OF: overlay: WARNING: memory leak will occur if overlay removed,
> > property: /soc/spi@e6e90000/status
> > OF: overlay: WARNING: memory leak will occur if overlay removed,
> > property: /__symbols__/msiof0_pins
> > spi_sh_msiof e6e90000.spi: DMA available
> > spi_sh_msiof e6e90000.spi: registered master spi0
> > spi spi0.0: setup mode 0, 8 bits/w, 100000 Hz max --> 0
> > at25 spi0.0: 512 Byte at25 eeprom, pagesize 16
> > spi_sh_msiof e6e90000.spi: registered child spi0.0
> >
> > Now it succeeds, and the SPI EEPROM is available, and works.
> >
> > Without this patch, or with this patch reverted after applying the
> > full series:
> >
> > $ overlay add 25lc040
> > OF: overlay: WARNING: memory leak will occur if overlay removed,
> > property: /keys/status
> > OF: overlay: WARNING: memory leak will occur if overlay removed,
> > property: /soc/spi@e6e90000/pinctrl-0
> > OF: overlay: WARNING: memory leak will occur if overlay removed,
> > property: /soc/spi@e6e90000/pinctrl-names
> > OF: overlay: WARNING: memory leak will occur if overlay removed,
> > property: /soc/spi@e6e90000/cs-gpios
> > OF: overlay: WARNING: memory leak will occur if overlay removed,
> > property: /soc/spi@e6e90000/status
> > OF: overlay: WARNING: memory leak will occur if overlay removed,
> > property: /__symbols__/msiof0_pins
> > OF: Not linking spi@e6e90000 to interrupt-controller@f1010000 - No
> > struct device
> > spi_sh_msiof e6e90000.spi: DMA available
> > spi_sh_msiof e6e90000.spi: registered master spi0
> > spi spi0.0: setup mode 0, 8 bits/w, 100000 Hz max --> 0
> > at25 spi0.0: 444 bps (2 bytes in 9 ticks)
> > at25 spi0.0: 512 Byte at25 eeprom, pagesize 16
> > spi_sh_msiof e6e90000.spi: registered child spi0.0
> >
> > The SPI EEPROM is available on the first try after boot.
>
> Sigh... I spent way too long trying to figure out if I caused a memory
> leak. I should have scrolled down further! Doesn't look like that part
> is related to anything I did.
>
> There are some flags set to avoid re-parsing fwnodes multiple times.
> My guess is that the issue you are seeing has to do with how many of
> the in memory structs are reused vs not when an overlay is
> applied/removed and some of these flags might not be getting cleared
> and this is having a bigger impact with this patch (because the fwnode
> links are no longer anchored on "compatible" nodes).
>
> With/without this patch (let's keep the series) can you look at how
> the following things change between each step you do above (add,
> remove, retry):
> 1) List of directories under /sys/class/devlink
> 2) Enable the debug logs inside __fwnode_link_add(),
> __fwnode_link_del(), device_link_add()

Without "of: property: Simplify of_link_to_phandle()":

- Adding overlay:

spi@e6e90000 Linked as a fwnode consumer to clock-controller@e6150000
spi@e6e90000 Linked as a fwnode consumer to system-controller@e6180000
spi@e6e90000 Linked as a fwnode consumer to pinctrl@e6060000
spi@e6e90000 Linked as a fwnode consumer to gpio@e6055000
platform e6e90000.spi: Linked as a consumer to e6055000.gpio
spi@e6e90000 Dropping the fwnode link to gpio@e6055000
platform e6e90000.spi: Linked as a consumer to e6060000.pinctrl
spi@e6e90000 Dropping the fwnode link to pinctrl@e6060000
spi@e6e90000 Dropping the fwnode link to system-controller@e6180000
platform e6e90000.spi: Linked as a consumer to e6150000.clock-controller
spi@e6e90000 Dropping the fwnode link to clock-controller@e6150000

+platform:e6055000.gpio--platform:e6e90000.spi ->
../../devices/virtual/devlink/platform:e6055000.gpio--platform:e6e90000.spi
+platform:e6060000.pinctrl--platform:e6e90000.spi ->
../../devices/virtual/devlink/platform:e6060000.pinctrl--platform:e6e90000.spi
+platform:e6150000.clock-controller--platform:e6e90000.spi ->
../../devices/virtual/devlink/platform:e6150000.clock-controller--platform:e6e90000.spi
-platform:e6060000.pinctrl--platform:keys ->
../../devices/virtual/devlink/platform:e6060000.pinctrl--platform:keys

SPI EEPROM works

- Removing overlay:

platform keys: Linked as a sync state only consumer to e6055000.gpio

-platform:e6055000.gpio--platform:e6e90000.spi ->
../../devices/virtual/devlink/platform:e6055000.gpio--platform:e6e90000.spi
-platform:e6060000.pinctrl--platform:e6e90000.spi ->
../../devices/virtual/devlink/platform:e6060000.pinctrl--platform:e6e90000.spi
-platform:e6150000.clock-controller--platform:e6e90000.spi ->
../../devices/virtual/devlink/platform:e6150000.clock-controller--platform:e6e90000.spi

platform:e6060000.pinctrl--platform:keys link is not recreated?!?!?

- Adding overlay again:

No debug output
No change in sys/class/devlink?!?!?
SPI EEPROM works


With "of: property: Simplify of_link_to_phandle()":

- Adding overlay:

spi@e6e90000 Linked as a fwnode consumer to
interrupt-controller@f1010000
spi@e6e90000 Linked as a fwnode consumer to clock-controller@e6150000
spi@e6e90000 Linked as a fwnode consumer to system-controller@e6180000
spi@e6e90000 Linked as a fwnode consumer to msiof0
spi@e6e90000 Linked as a fwnode consumer to gpio@e6055000
platform e6e90000.spi: Linked as a consumer to e6055000.gpio
spi@e6e90000 Dropping the fwnode link to gpio@e6055000
spi@e6e90000 Dropping the fwnode link to system-controller@e6180000
platform e6e90000.spi: Linked as a consumer to e6150000.clock-controller
spi@e6e90000 Dropping the fwnode link to clock-controller@e6150000
platform e6e90000.spi: Linked as a consumer to soc
spi@e6e90000 Dropping the fwnode link to interrupt-controller@f1010000

+platform:e6055000.gpio--platform:e6e90000.spi ->
../../devices/virtual/devlink/platform:e6055000.gpio--platform:e6e90000.spi
+platform:e6150000.clock-controller--platform:e6e90000.spi ->
../../devices/virtual/devlink/platform:e6150000.clock-controller--platform:e6e90000.spi
+platform:soc--platform:e6e90000.spi ->
../../devices/virtual/devlink/platform:soc--platform:e6e90000.spi

-platform:e6060000.pinctrl--platform:keys ->
../../devices/virtual/devlink/platform:e6060000.pinctrl--platform:keys

SPI EEPROM does not work

- Removing overlay:

platform keys: Linked as a sync state only consumer to e6055000.gpio
spi@e6e90000 Dropping the fwnode link to msiof0

-platform:e6055000.gpio--platform:e6e90000.spi ->
../../devices/virtual/devlink/platform:e6055000.gpio--platform:e6e90000.spi
-platform:e6150000.clock-controller--platform:e6e90000.spi ->
../../devices/virtual/devlink/platform:e6150000.clock-controller--platform:e6e90000.spi
-platform:soc--platform:e6e90000.spi ->
../../devices/virtual/devlink/platform:soc--platform:e6e90000.spi

platform:e6060000.pinctrl--platform:keys link is not recreated?!?!?


- Adding overlay again:

No debug output
No change in sys/class/devlink?!?!?
SPI EEPROM works

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

\
 
 \ /
  Last update: 2023-03-27 00:20    [W:0.126 / U:0.204 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site