Re: [PATCH] watchdog: ixp4xx: Use devm_clk_get_enabled() helper

From: Christophe JAILLET
Date: Sun Jan 01 2023 - 12:52:48 EST


Le 01/01/2023 à 16:07, Guenter Roeck a écrit :
On Sun, Jan 01, 2023 at 10:35:59AM +0100, Christophe JAILLET wrote:
Le 01/01/2023 à 00:14, Guenter Roeck a écrit :
On Sat, Dec 31, 2022 at 12:07:27PM +0100, Christophe JAILLET wrote:
The devm_clk_get_enabled() helper:
- calls devm_clk_get()
- calls clk_prepare_enable() and registers what is needed in order to
call clk_disable_unprepare() when needed, as a managed resource.

This simplifies the code and avoids the need of a dedicated function used
with devm_add_action_or_reset().

Signed-off-by: Christophe JAILLET <christophe.jaillet-39ZsbGIQGT5GWvitb5QawA@xxxxxxxxxxxxxxxx>
---
Note that I get a compilation error because read_cpuid_id() is not defined
on my system (x86_64).
So I think that a "depends on ARM<something>" in missing in a KConfig file.

It has

depends on ARCH_IXP4XX

and CONFIG_IXP4XX_WATCHDOG is not set for me after "make allmodconfig".

Here is what do.

make allmodconfig
make -j8 drivers/watchdog/ixp4xx_wdt.o

And I get:
DESCEND objtool
CALL scripts/checksyscalls.sh
CC drivers/watchdog/ixp4xx_wdt.o
drivers/watchdog/ixp4xx_wdt.c: In function ‘ixp4xx_wdt_probe’:
drivers/watchdog/ixp4xx_wdt.c:122:15: error: implicit declaration of
function ‘read_cpuid_id’ [-Werror=implicit-function-declaration]
122 | if (!(read_cpuid_id() & 0xf) && !cpu_is_ixp46x()) {
| ^~~~~~~~~~~~~
cc1: all warnings being treated as errors
make[3]: *** [scripts/Makefile.build:252 : drivers/watchdog/ixp4xx_wdt.o]
Erreur 1
make[2]: *** [scripts/Makefile.build:504 : drivers/watchdog] Erreur 2
make[1]: *** [scripts/Makefile.build:504 : drivers] Erreur 2
make: *** [Makefile:2011 : .] Erreur 2


I do agree with you that:

- Kconfig looks fine
config IXP4XX_WATCHDOG
tristate "IXP4xx Watchdog"
depends on ARCH_IXP4XX

- Makefile looks fine
obj-$(CONFIG_IXP4XX_WATCHDOG) += ixp4xx_wdt.o

- .config looks fine
IXP4XX_WATCHDOG is NOT defined

- make drivers/watchdog/ looks fine
No error and ixp4xx_wdt.o is NOT built.


However, in the past (if I recollect correctly :) ), a "make <something_that
depends_on_a_config_variable_that_is_not_defined>" returned an error stating
that no rule existed to build the specified target.


This is not correct. It only applies if the target directory Makefile is
excluded by the make flags, or possibly if the target file is a complex
one build from various source files.

I sometimes needed to tweak the Kconfig files to force some compilation when
I didn't have the right tool chain or configuration.
It was maybe not the best practice, but it worked most of the time.


Now, with the example above, such a compilation attempt is possible. It is
maybe normal (because of a change somewhere in the way the kernel is built,
because of an updated toolchain on my machine, ...)
This is just fine for me, but looked really surprising.

That is why I first thought that something was missing in a Kconfig file.


So my comments are just a surprise to me to something that seems not to
behave the same as before.

I don't think anything changed. It always worked like that for me.
I would suggest to go back to an older kernel and try it there.
You'll see exactly the same error. Maybe you just never encountered
a file like that.

git reset --hard next-20210111 (randomly chosen date)
make allmodconfig
make clean
make -j7 drivers/watchdog/ixp4xx_wdt.o (too build most of the needed stuff to build a kernel)
touch drivers/watchdog/ixp4xx_wdt.c
make -j7 drivers/watchdog/ixp4xx_wdt.o (too build this file only)

DESCEND objtool
CALL scripts/atomic/check-atomics.sh
CALL scripts/checksyscalls.sh
make[3]: *** Aucune règle pour fabriquer la cible « drivers/watchdog/ixp4xx_wdt.o ». Arrêt.
make[2]: *** [scripts/Makefile.build:471 : __build] Erreur 2
make[1]: *** [scripts/Makefile.build:496 : drivers/watchdog] Erreur 2
make: *** [Makefile:1805 : drivers] Erreur 2


This is what I had in mind.
(Aucune règle pour fabriquer la cible... = no rule to build...)


So something changed somewhere. Maybe in the way Makefile are now included or not in the build process, as you suggest above.


So, in other words, what you should have said is "not compile tested".
Alternatively, you could install cross compilers and compile test the
patches with those.


No. The patches HAVE been cross compiled after my initial attempt with my default x86_64 failing built.


This one was successfully built using:
make ARCH=arm CROSS_COMPILE=/usr/bin/arm-linux-gnueabi- allmodconfig
make ARCH=arm CROSS_COMPILE=/usr/bin/arm-linux-gnueabi- -j7 drivers/watchdog/ixp4xx_wdt.o


The other one was successfully built using:
make ARCH=mips CROSS_COMPILE=mips64-linux-gnuabi64- allmodconfig
Changing CONFIG_MACH_LOONGSON32 to y, instead of CONFIG_MIPS_GENERIC_KERNEL
make ARCH=mips CROSS_COMPILE=mips64-linux-gnuabi64- -j7 drivers/watchdog/loongson1_wdt.o

I've long been reluctant to use cross-compiler because of low disk space on my system. But I've changed my mind recently and now I do cross compile. (see [1] if needed as example also with ARCH=arm)


My comments below the --- in the patches should not be taken as "I've not managed to build with the patch", but "I've been surprised to get an issue with x86_64, then cross-compiled with the relevant toolchain. Then, I reported what looked like a potential issue when building with x86_64."

CJ

[1]: https://lore.kernel.org/all/dc5a2157-19c8-4498-6288-d7513ad3dde2@xxxxxxxxxx/


Thanks,
Guenter