Build failure in -next due to 'rtc: cmos: move mc146818rtc code out of asm-generic/rtc.h'

Hi Arnd,

sparc32:allmodconfig fails to build in next-20160602 as follows.

In file included from drivers/block/floppy.c:185:0:
include/linux/mc146818rtc.h: In function 'mc146818_is_updating':
include/linux/mc146818rtc.h:138:9: error: 'rtc_port' undeclared (first use in this function) include/linux/mc146818rtc.h:138:9: note: each undeclared identifier is reported only once for each function it appears in include/linux/mc146818rtc.h: In function 'mc146818_get_time':
include/linux/mc146818rtc.h:172:17: error: 'rtc_port' undeclared (first use in this function) include/linux/mc146818rtc.h: In function 'mc146818_set_time':
include/linux/mc146818rtc.h:278:8: error: 'rtc_port' undeclared (first use in this function) scripts/Makefile.build:295: recipe for target 'drivers/block/floppy.o' failed

Bisect points to commit fd09cc80165c ("rtc: cmos: move mc146818rtc code out of asm-generic/rtc.h"). Bisct log is attached.

Note that removing the offending include file works for sparc32 but not for x86; it results in a missing definition of CMOS_READ().

---
Bisect log:

# bad: [bb65e54d78161268e500e9744342920de782874e] mn10300: Add missing include file to proc-init.c # good: [1a695a905c18548062509178b98bc91e67510864] Linux 4.7-rc1
git bisect start 'HEAD' 'v4.7-rc1'
# good: [2dcacc3943642b0e8f403c486b56fecb054e9764] Merge remote-tracking branch 'thermal/next' git bisect good 2dcacc3943642b0e8f403c486b56fecb054e9764
# good: [07f0ec96d422b0d454b5cbf4fdd732c27f053d1d] Merge remote-tracking branch 'sound/for-next' git bisect good 07f0ec96d422b0d454b5cbf4fdd732c27f053d1d
# good: [6ef7078aac785fceffc4bce468ccf68ff20826fa] Merge remote-tracking branch 'spi/for-next' git bisect good 6ef7078aac785fceffc4bce468ccf68ff20826fa
# good: [9fc82ec042e638ea8b45c7f44bc6f7c366758545] Merge remote-tracking branch 'pinctrl/for-next' git bisect good 9fc82ec042e638ea8b45c7f44bc6f7c366758545
# good: [179a961299a005ab2b3813c545e59aa05e9a803b] Merge remote-tracking branch 'coresight/next' git bisect good 179a961299a005ab2b3813c545e59aa05e9a803b
# good: [8d2a69f1b02b4c2b340d7b9036fee573d9b1c2f1] samples/kprobe: convert the printk to pr_info/pr_err git bisect good 8d2a69f1b02b4c2b340d7b9036fee573d9b1c2f1
# bad: [95df4c078bf315b7590d4439db24494837bddf88] char/genrtc: remove the rest of the driver git bisect bad 95df4c078bf315b7590d4439db24494837bddf88
# bad: [6187350e54676a69d9742aaa9c30720d146df4a2] rtc: parisc: provide rtc_class_ops directly git bisect bad 6187350e54676a69d9742aaa9c30720d146df4a2
# bad: [fd09cc80165cc96a2cd42abed98553549b4d09fc] rtc: cmos: move mc146818rtc code out of asm-generic/rtc.h git bisect bad fd09cc80165cc96a2cd42abed98553549b4d09fc
# good: [7af6a2e1c2565396f6b941ff2a989b989b24a97b] MAINTAINERS: Add file patterns for rtc device tree bindings git bisect good 7af6a2e1c2565396f6b941ff2a989b989b24a97b
# good: [23999733c6445da22a12d373cb45d64f0afe462a] rtc: cmos: remove empty asm/mc146818rtc.h files git bisect good 23999733c6445da22a12d373cb45d64f0afe462a

# first bad commit: [fd09cc80165cc96a2cd42abed98553549b4d09fc] rtc: cmos: move mc146818rtc code out of asm-generic/rtc.h

Quoted 14 lines · CEST Guenter Roeck

Hi Arnd,

sparc32:allmodconfig fails to build in next-20160602 as follows.

In file included from drivers/block/floppy.c:185:0:
include/linux/mc146818rtc.h: In function 'mc146818_is_updating':
include/linux/mc146818rtc.h:138:9: error: 'rtc_port' undeclared (first use in this function) include/linux/mc146818rtc.h:138:9: note: each undeclared identifier is reported only once for each function it appears in include/linux/mc146818rtc.h: In function 'mc146818_get_time':
include/linux/mc146818rtc.h:172:17: error: 'rtc_port' undeclared (first use in this function) include/linux/mc146818rtc.h: In function 'mc146818_set_time':
include/linux/mc146818rtc.h:278:8: error: 'rtc_port' undeclared (first use in this function) scripts/Makefile.build:295: recipe for target 'drivers/block/floppy.o' failed

Quoted 5 lines

Bisect points to commit fd09cc80165c ("rtc: cmos: move mc146818rtc code out of asm-generic/rtc.h"). Bisct log is attached.

Note that removing the offending include file works for sparc32 but not for x86; it results in a missing definition of CMOS_READ().

I have trouble reproducing this, but I think the problem here is that there are two definitions of CMOS_READ() in sparc, and we pick up the wrong one
here: there is no 'rtc_port' variable outside of drivers/char/rtc.c, and we don't build that file any more on sparc32, so we probably want this patch:

arch/sparc/include/asm/io_32.h +0 -10

index 57f26c398dc9..4dd268a3a8b0 100644
@@ -140,16 +140,6 @@ void ioport_unmap(void __iomem *);
  struct pci_dev;
  void pci_iounmap(struct pci_dev *dev, void __iomem *);
 
-
-
-/*
- * At the moment, we do not use CMOS_READ anywhere outside of rtc.c,
- * so rtc_port is static in it. This should not change unless a new
- * hardware pops up.
- */
-#define RTC_PORT(x)   (rtc_port + (x))
-#define RTC_ALWAYS_BCD  0
-
  static inline int sbus_can_dma_64bit(void)
  {
  	return 0; /* actually, sparc_cpu_model==sun4d */

Can you check if this fixes the problem?

Quoted 29 lines · Arnd Bergmann

I have trouble reproducing this, but I think the problem here is that there are two definitions of CMOS_READ() in sparc, and we pick up the wrong one
here: there is no 'rtc_port' variable outside of drivers/char/rtc.c, and we don't build that file any more on sparc32, so we probably want this patch:

arch/sparc/include/asm/io_32.h +0 -10

index 57f26c398dc9..4dd268a3a8b0 100644
@@ -140,16 +140,6 @@ void ioport_unmap(void __iomem *);
  struct pci_dev;
  void pci_iounmap(struct pci_dev *dev, void __iomem *);
 
-
-
-/*
- * At the moment, we do not use CMOS_READ anywhere outside of rtc.c,
- * so rtc_port is static in it. This should not change unless a new
- * hardware pops up.
- */
-#define RTC_PORT(x)   (rtc_port + (x))
-#define RTC_ALWAYS_BCD  0
-
  static inline int sbus_can_dma_64bit(void)
  {
  	return 0; /* actually, sparc_cpu_model==sun4d */

Quoted 2 lines

Can you check if this fixes the problem?

Yes, it does. I did test builds with both sparc:allmodconfig and sparc64:allmodconfig after applying above diff; both passed.

Arnd, do you mind sending a proper patch that I'll apply before 'rtc:
cmos: move mc146818rtc code out of asm-generic/rtc.h'? Else, I could squash it in but I think the former is cleaner.