diff mbox series

[v5,6/7] pwm: lpss: Add devm_pwm_lpss_probe() stub

Message ID 20221117110806.65470-7-andriy.shevchenko@linux.intel.com
State New
Headers show
Series [v5,1/7] pwm: Add a stub for devm_pwmchip_add() | expand

Commit Message

Andy Shevchenko Nov. 17, 2022, 11:08 a.m. UTC 
In case the PWM LPSS module is not provided, allow users to be
compiled with the help of the devm_pwm_lpss_probe() stub.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Thierry Reding <thierry.reding@gmail.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 include/linux/platform_data/x86/pwm-lpss.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

Comments

Uwe Kleine-König Nov. 22, 2022, 6:14 p.m. UTC | #1 
Hello Andy,

On Tue, Nov 22, 2022 at 07:35:38PM +0200, Andy Shevchenko wrote:
> On Tue, Nov 22, 2022 at 05:47:03PM +0100, Uwe Kleine-König wrote:
> > On Thu, Nov 17, 2022 at 01:08:05PM +0200, Andy Shevchenko wrote:
> > > In case the PWM LPSS module is not provided, allow users to be
> > > compiled with the help of the devm_pwm_lpss_probe() stub.
> 
> ...
> 
> > > +static inline
> > > +struct pwm_lpss_chip *devm_pwm_lpss_probe(struct device *dev, void __iomem *base,
> > > +					  const struct pwm_lpss_boardinfo *info)
> > > +{
> > > +	return ERR_PTR(-ENODEV);
> > > +}
> > > +#endif	/* CONFIG_PWM_LPSS */
> > 
> > Hmm, this is actually never used, because if
> > !IS_REACHABLE(CONFIG_PWM_LPSS), the only caller (that is added in patch
> > 7) has:
> > 
> > 	if (!IS_REACHABLE(CONFIG_PWM_LPSS))
> > 		return 0;
> > 
> > before devm_pwm_lpss_probe() is called.
> > 
> > Not sure if it's safe to just drop this patch.
> 
> How is it supposed to be compiled and linked then?

The compiler optimizes everything away after that return 0 and so
doesn't need that symbol at all.

I just tested compiling your series without patch #6, x86_64 allmodconfig + PWM=n.

nm doesn't report the need for devm_pwm_lpss_probe in
drivers/pinctrl/intel/pinctrl-intel.o.

The build isn't done yet, but I don't expect surprises.

Best regards
Uwe
Uwe Kleine-König Nov. 22, 2022, 8:21 p.m. UTC | #2 
Hello Andy,

On Tue, Nov 22, 2022 at 08:32:53PM +0200, Andy Shevchenko wrote:
> On Tue, Nov 22, 2022 at 07:14:44PM +0100, Uwe Kleine-König wrote:
> > I just tested compiling your series without patch #6, x86_64 allmodconfig + PWM=n.
> > 
> > nm doesn't report the need for devm_pwm_lpss_probe in
> > drivers/pinctrl/intel/pinctrl-intel.o.
> 
> Sounds like you are right. I tried a brief test with m/m, y/m, m/y, and m/n
> variants between PINCTRL_INTEL and PWM_LPSS and all were built fine.
> 
> That said, I will drop this patch and send a PR with the rest.

Sounds good.

> Thank you for thorough review!

Thank you for the interesting thread. I like our conversations.

Best regards
Uwe
diff mbox series

Patch

diff --git a/include/linux/platform_data/x86/pwm-lpss.h b/include/linux/platform_data/x86/pwm-lpss.h
index c852fe24fe2a..6ef21b8baec7 100644
--- a/include/linux/platform_data/x86/pwm-lpss.h
+++ b/include/linux/platform_data/x86/pwm-lpss.h
@@ -4,6 +4,8 @@ 
 #ifndef __PLATFORM_DATA_X86_PWM_LPSS_H
 #define __PLATFORM_DATA_X86_PWM_LPSS_H
 
+#include <linux/err.h>
+#include <linux/kconfig.h>
 #include <linux/types.h>
 
 struct device;
@@ -27,7 +29,16 @@  struct pwm_lpss_boardinfo {
 	bool other_devices_aml_touches_pwm_regs;
 };
 
+#if IS_REACHABLE(CONFIG_PWM_LPSS)
 struct pwm_lpss_chip *devm_pwm_lpss_probe(struct device *dev, void __iomem *base,
 					  const struct pwm_lpss_boardinfo *info);
+#else
+static inline
+struct pwm_lpss_chip *devm_pwm_lpss_probe(struct device *dev, void __iomem *base,
+					  const struct pwm_lpss_boardinfo *info)
+{
+	return ERR_PTR(-ENODEV);
+}
+#endif	/* CONFIG_PWM_LPSS */
 
 #endif	/* __PLATFORM_DATA_X86_PWM_LPSS_H */