linux-kernel - Re: rtc regression [463a86304cae ("char/genrtc: x86: remove remnants of asm/rtc.h")]

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Date:	Tue, 09 Aug 2016 18:09:27 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Ville Syrjälä <ville.syrjala@...ux.intel.com>
Cc:	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Alessandro Zummo <a.zummo@...ertech.it>,
	linux-kernel@...r.kernel.org, rtc-linux@...glegroups.com
Subject: Re: rtc regression [463a86304cae ("char/genrtc: x86: remove remnants of asm/rtc.h")]

On Tuesday, August 9, 2016 6:56:49 PM CEST Ville Syrjälä wrote:
> Hi,
> 
> commit 463a86304cae ("char/genrtc: x86: remove remnants of asm/rtc.h")
> broke rtc for me. Neither hwclock or rtcwake work anymore. This is just
> a very standard x86-64 IVB box, and it was reported that machines in
> our i915 test farm are having rtc related problems as well.
> 
> The first time I run hwclock after rebooting I get this:
>  open("/dev/rtc", O_RDONLY)              = 3
>  ioctl(3, PHN_SET_REGS or RTC_UIE_ON, 0) = 0
>  select(4, [3], NULL, NULL, {10, 0})     = 0 (Timeout)
>  ioctl(3, PHN_NOT_OH or RTC_UIE_OFF, 0)  = 0
>  close(3)                                = 0
> 
> On all subsequent runs I get this:
>  open("/dev/rtc", O_RDONLY)              = 3
>  ioctl(3, PHN_SET_REGS or RTC_UIE_ON, 0) = -1 EINVAL (Invalid argument)
>  ioctl(3, RTC_RD_TIME, 0x7ffd76b3ae70)   = -1 EINVAL (Invalid argument)
>  close(3)                                = 0
> 
> 463a86304cae^ gets me back to working condition:
>  open("/dev/rtc", O_RDONLY)              = 3
>  ioctl(3, PHN_SET_REGS or RTC_UIE_ON, 0) = 0
>  select(4, [3], NULL, NULL, {10, 0})     = 1 (in [3], left {9, 530998})
>  ioctl(3, PHN_NOT_OH or RTC_UIE_OFF, 0)  = 0
>  ioctl(3, RTC_RD_TIME, {tm_sec=20, tm_min=17, tm_hour=15, tm_mday=9, tm_mon=7, tm_year=116, ...}) = 0
>  close(3)                                = 0

That commit was supposed to have no effect on the binary, but it
seems I had a typo in one file. Can you try this patch on top
of mainline?

	Arnd

diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index ed16e58658a4..c6dfd801df97 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -1242,7 +1242,7 @@ irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id)
 	memset(&curr_time, 0, sizeof(struct rtc_time));
 
 	if (hpet_rtc_flags & (RTC_UIE | RTC_AIE))
-		mc146818_set_time(&curr_time);
+		mc146818_get_time(&curr_time);
 
 	if (hpet_rtc_flags & RTC_UIE &&
 	    curr_time.tm_sec != hpet_prev_update_sec) {