watchdog: coh901327: add COMMON_CLK dependency

Message ID 20201203223358.1269372-1-arnd@kernel.org
State New
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Series
  • watchdog: coh901327: add COMMON_CLK dependency
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Commit Message

Arnd Bergmann Dec. 3, 2020, 10:33 p.m.
From: Arnd Bergmann <arnd@arndb.de>


clang produces a build failure in configurations without COMMON_CLK
when a timeout calculation goes wrong:

arm-linux-gnueabi-ld: drivers/watchdog/coh901327_wdt.o: in function `coh901327_enable':
coh901327_wdt.c:(.text+0x50): undefined reference to `__bad_udelay'

Add a Kconfig dependency to only do build testing when COMMON_CLK
is enabled.

Fixes: da2a68b3eb47 ("watchdog: Enable COMPILE_TEST where possible")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
 drivers/watchdog/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-- 
2.27.0

Comments

Guenter Roeck Dec. 4, 2020, 1:41 a.m. | #1
On Thu, Dec 03, 2020 at 11:33:42PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>

> 

> clang produces a build failure in configurations without COMMON_CLK

> when a timeout calculation goes wrong:

> 

> arm-linux-gnueabi-ld: drivers/watchdog/coh901327_wdt.o: in function `coh901327_enable':

> coh901327_wdt.c:(.text+0x50): undefined reference to `__bad_udelay'

> 

> Add a Kconfig dependency to only do build testing when COMMON_CLK

> is enabled.

> 

> Fixes: da2a68b3eb47 ("watchdog: Enable COMPILE_TEST where possible")

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>


Reviewed-by: Guenter Roeck <linux@roeck-us.net>


> ---

>  drivers/watchdog/Kconfig | 2 +-

>  1 file changed, 1 insertion(+), 1 deletion(-)

> 

> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig

> index 8bdbd125821b..32fa6de7b820 100644

> --- a/drivers/watchdog/Kconfig

> +++ b/drivers/watchdog/Kconfig

> @@ -631,7 +631,7 @@ config SUNXI_WATCHDOG

>  

>  config COH901327_WATCHDOG

>  	bool "ST-Ericsson COH 901 327 watchdog"

> -	depends on ARCH_U300 || (ARM && COMPILE_TEST)

> +	depends on ARCH_U300 || (ARM && COMMON_CLK && COMPILE_TEST)

>  	default y if MACH_U300

>  	select WATCHDOG_CORE

>  	help

> -- 

> 2.27.0

>
Nick Desaulniers Dec. 10, 2020, 11 p.m. | #2
On Thu, Dec 3, 2020 at 2:34 PM Arnd Bergmann <arnd@kernel.org> wrote:
>

> From: Arnd Bergmann <arnd@arndb.de>

>

> clang produces a build failure in configurations without COMMON_CLK

> when a timeout calculation goes wrong:

>

> arm-linux-gnueabi-ld: drivers/watchdog/coh901327_wdt.o: in function `coh901327_enable':

> coh901327_wdt.c:(.text+0x50): undefined reference to `__bad_udelay'


Isn't a linkage failure against __bad_udelay supposed to be
interpreted as a value too large being passed to udelay()? IIRC, this
was an issue for someone building an Apple touchpad driver with Clang
at -O3...you sent a fix for that:
https://github.com/ClangBuiltLinux/linux/issues/678,
https://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging.git/commit/?id=fff2d0f701e6753591609739f8ab9be1c8e80ebb.

>

> Add a Kconfig dependency to only do build testing when COMMON_CLK

> is enabled.

>

> Fixes: da2a68b3eb47 ("watchdog: Enable COMPILE_TEST where possible")

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

> ---

>  drivers/watchdog/Kconfig | 2 +-

>  1 file changed, 1 insertion(+), 1 deletion(-)

>

> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig

> index 8bdbd125821b..32fa6de7b820 100644

> --- a/drivers/watchdog/Kconfig

> +++ b/drivers/watchdog/Kconfig

> @@ -631,7 +631,7 @@ config SUNXI_WATCHDOG

>

>  config COH901327_WATCHDOG

>         bool "ST-Ericsson COH 901 327 watchdog"

> -       depends on ARCH_U300 || (ARM && COMPILE_TEST)

> +       depends on ARCH_U300 || (ARM && COMMON_CLK && COMPILE_TEST)

>         default y if MACH_U300

>         select WATCHDOG_CORE

>         help

> --

> 2.27.0

>



-- 
Thanks,
~Nick Desaulniers
Guenter Roeck Dec. 11, 2020, 12:16 a.m. | #3
On Thu, Dec 10, 2020 at 03:00:30PM -0800, Nick Desaulniers wrote:
> On Thu, Dec 3, 2020 at 2:34 PM Arnd Bergmann <arnd@kernel.org> wrote:

> >

> > From: Arnd Bergmann <arnd@arndb.de>

> >

> > clang produces a build failure in configurations without COMMON_CLK

> > when a timeout calculation goes wrong:

> >

> > arm-linux-gnueabi-ld: drivers/watchdog/coh901327_wdt.o: in function `coh901327_enable':

> > coh901327_wdt.c:(.text+0x50): undefined reference to `__bad_udelay'

> 

> Isn't a linkage failure against __bad_udelay supposed to be

> interpreted as a value too large being passed to udelay()? IIRC, this

> was an issue for someone building an Apple touchpad driver with Clang

> at -O3...you sent a fix for that:

> https://github.com/ClangBuiltLinux/linux/issues/678,

> https://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging.git/commit/?id=fff2d0f701e6753591609739f8ab9be1c8e80ebb.


The problem is likely that clk_get_rate() returns a constant 0,
which in the real world would end up in a divide by 0 crash.
An alternative might be be to add

	freq = clk_get_rate(clk);
-->	if (freq == 0)
-->		return;

but I don't know if that would really be worth the effort.
I prefer the current fix.

Guenter

> 

> >

> > Add a Kconfig dependency to only do build testing when COMMON_CLK

> > is enabled.

> >

> > Fixes: da2a68b3eb47 ("watchdog: Enable COMPILE_TEST where possible")

> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>

> > ---

> >  drivers/watchdog/Kconfig | 2 +-

> >  1 file changed, 1 insertion(+), 1 deletion(-)

> >

> > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig

> > index 8bdbd125821b..32fa6de7b820 100644

> > --- a/drivers/watchdog/Kconfig

> > +++ b/drivers/watchdog/Kconfig

> > @@ -631,7 +631,7 @@ config SUNXI_WATCHDOG

> >

> >  config COH901327_WATCHDOG

> >         bool "ST-Ericsson COH 901 327 watchdog"

> > -       depends on ARCH_U300 || (ARM && COMPILE_TEST)

> > +       depends on ARCH_U300 || (ARM && COMMON_CLK && COMPILE_TEST)

> >         default y if MACH_U300

> >         select WATCHDOG_CORE

> >         help

> > --

> > 2.27.0

> >

> 

> 

> -- 

> Thanks,

> ~Nick Desaulniers

Patch

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 8bdbd125821b..32fa6de7b820 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -631,7 +631,7 @@  config SUNXI_WATCHDOG
 
 config COH901327_WATCHDOG
 	bool "ST-Ericsson COH 901 327 watchdog"
-	depends on ARCH_U300 || (ARM && COMPILE_TEST)
+	depends on ARCH_U300 || (ARM && COMMON_CLK && COMPILE_TEST)
 	default y if MACH_U300
 	select WATCHDOG_CORE
 	help