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SubjectRe: [PATCH 2/2] pwm: Enable compile testing for some of drivers
Hello Krzysztof,

On Tue, Jan 07, 2020 at 09:25:39AM +0100, Krzysztof Kozlowski wrote:
> On Tue, Jan 07, 2020 at 08:26:45AM +0100, Uwe Kleine-König wrote:
> > On Mon, Dec 30, 2019 at 06:21:13PM +0100, Krzysztof Kozlowski wrote:
> > > Some of the PWM drivers can be compile tested to increase build
> > > coverage.
> > >
> > > The Meson PWM driver requires COMMON_CLK dependency.
> >
> > I'm surprised that there are not more that need this. Is HAVE_CLK not
> > enough?
>
> Nope. E.g. for alpha architecture, HAVE_CLK is not set and without
> COMMON_CLK:
>
> drivers/pwm/pwm-meson.o: In function `meson_pwm_init_channels':
> (.text+0x244): undefined reference to `devm_clk_register'

I see. devm_clk_register() only exists in include/linux/clk-provider.h.

> I guess other solution would be to add stubs for few clk functions...
>
> > Also HAS_IOMEM is a typical requirement, but I tested with an ARCH=um
> > config (which does't have HAS_IOMEM) and they all compile fine.
>
> Because of !HAS_IOMEM, since some time ARCH=um does not support
> COMPILE_TEST. Therefore HAS_IOMEM dependency is not needed for compile
> testing (and for regular build it is selected by ARCH).

Hehe, I didn't notice because for testing I just dropped the "depends on
..." lines in Kconfig instead of adding "|| COMPILE_TEST" :-) Still they
compile fine on UML.

Ah, since bc083a64b6c0 ("init/Kconfig: make COMPILE_TEST depend on
!UML") == v4.8-rc1~52^2~83 COMPILE_TEST cannot be enabled on UML, but
later 1bcbfbfdeb00 ("um: add dummy ioremap and iounmap functions")
== v4.13-rc1~8^2~6 UM got a dummy implementation. So maybe we could
revert bc083a64b6c0 today? (And if not, a comment about why near the
"depends on !UML" in init/Kconfig would be great.)

Orthogonal to that, I wonder if depending on HAS_IOMEM is right even
though the compile testers won't notice it missing. Or should HAS_IOMEM
be dropped?

> > > @@ -318,7 +319,7 @@ config PWM_MEDIATEK
> > >
> > > config PWM_MXS
> > > tristate "Freescale MXS PWM support"
> > > - depends on ARCH_MXS && OF
> > > + depends on (ARCH_MXS && OF) || COMPILE_TEST
> > > select STMP_DEVICE
> > > help
> > > Generic PWM framework driver for Freescale MXS.
> > > @@ -328,7 +329,8 @@ config PWM_MXS
> > >
> > > config PWM_OMAP_DMTIMER
> > > tristate "OMAP Dual-Mode Timer PWM support"
> > > - depends on OF && ARCH_OMAP && OMAP_DM_TIMER
> > > + depends on (ARCH_OMAP && OMAP_DM_TIMER) || COMPILE_TEST
> > > + depends on OF
> >
> > I'm surprised that OF isn't required for PWM_MXS but is is for
> > PWM_OMAP_DMTIMER. pwm-mxs compiles without CONFIG_OF, didn't test
> > pwm-omap-dmtimer.
>
> Since some time !OF has all necessary stubs so OF is actually needed
> only for binding, not compiling.

That doesn't explain why you handle PWM_MXS and PWM_OMAP_DMTIMER
differently though.

Best regards
Uwe

--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |

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