Real time clock seems stuck

Real time clock seems stuck

[Dr. Craig Hollabaugh]

Folks,

I'm trying to get a walnut board booted. I'm using linuxppc_2_4_devel pulled from denx yesterday. I'm getting the "Real time clock seems stuck" message then nothing, no messages after that. I found a brief thread about this.

http://lists.linuxppc.org/linuxppc-embedded/200106/msg00113.html

Have the changes suggested been put in the devel tree? If so, can someone offer some advice on how to proceed?

Here's some console output.

PPCBoot 1.2.0 (Oct 20 2002 - 19:03:26)

CPU:   IBM PowerPC 405GP Rev. D at 200 MHz (PLB=100, OPB=50, EBC=50 MHz)
           PCI sync clock at 33 MHz, internal PCI arbiter enabled
           16 kB I-Cache 8 kB D-Cache
Board: ### No HW ID - assuming WALNUT405
I2C:   ready
DRAM:  32 MB
FLASH: 512 kB
In:    serial
Out:   serial
Err:   serial
KGDB:  kgdb ready
ready
BEDBUG:ready

=> tftpboot 400000 p1
ENET Speed is 100 Mbps - FULL duplex connection
ARP broadcast 1
TFTP from server 192.168.1.11; our IP address is 192.168.1.111
Filename 'p1'.
Load address: 0x400000
Loading: #################################################################
         ############################################
done
Bytes transferred = 557872 (88330 hex)
=> imi 400000

## Checking Image at 00400000 ...
   Image Name:   Linux-2.4.20-pre11
   Created:      2002-10-31  12:17:56 UTC
   Image Type:   PowerPC Linux Kernel Image (gzip compressed)
   Data Size:    557808 Bytes = 544.7 kB
   Load Address: 00000000
   Entry Point:  00000000
   Verifying Checksum ... OK
=> bootm 400000
## Booting image at 00400000 ...
   Image Name:   Linux-2.4.20-pre11
   Created:      2002-10-31  12:17:56 UTC
   Image Type:   PowerPC Linux Kernel Image (gzip compressed)
   Data Size:    557808 Bytes = 544.7 kB
   Load Address: 00000000
   Entry Point:  00000000
   Verifying Checksum ... OK
   Uncompressing Kernel Image ... OK
Linux version 2.4.20-pre11 (root@tbdev1) (gcc version 2.95.4 20010319 (prerelease/franzo/20011204)) #12 Thu Oct 31 05:13:53 MST 2002
IBM Walnut port (C) 2000-2002 MontaVista Software, Inc. (source@mvista.com)
On node 0 totalpages: 1295
zone(0): 1295 pages.
zone(1): 0 pages.
zone(2): 0 pages.
Kernel command line: console=ttyS0,9600 root=/dev/ram
Warning: real time clock seems stuck!



then nothing after that.

Any ideas? I've searched the archives for walnut boot problems. It seems like most people just get it running and that's that.

Thanks
Craig


** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

RE: Real time clock seems stuck

[Jeff David]

You may be loading the code too low.  See the comments for the
CFG_BOOTMAPSZ parameter in CONFIG_WALNUT405.h and cmd_bootm.c.  Try
loading at 0x800000 instead.

Jeff


> -----Original Message-----
> From: Dr. Craig Hollabaugh [mailto:craig@hollabaugh.com]
> Sent: Thursday, October 31, 2002 7:30 AM
> To: linuxppc-embedded@lists.linuxppc.org
> Subject: Real time clock seems stuck
>
>
>
> Folks,
>
> I'm trying to get a walnut board booted. I'm using
> linuxppc_2_4_devel pulled from denx yesterday. I'm getting
> the "Real time clock seems stuck" message then nothing, no
> messages after that. I found a brief thread about this.
>
> http://lists.linuxppc.org/linuxppc-embedded/200106/msg00113.html
>
> Have the changes suggested been put in the devel tree? If so,
> can someone offer some advice on how to proceed?
>
> Here's some console output.
>
> PPCBoot 1.2.0 (Oct 20 2002 - 19:03:26)
>
> CPU:   IBM PowerPC 405GP Rev. D at 200 MHz (PLB=100, OPB=50,
> EBC=50 MHz)
>            PCI sync clock at 33 MHz, internal PCI arbiter enabled
>            16 kB I-Cache 8 kB D-Cache
> Board: ### No HW ID - assuming WALNUT405
> I2C:   ready
> DRAM:  32 MB
> FLASH: 512 kB
> In:    serial
> Out:   serial
> Err:   serial
> KGDB:  kgdb ready
> ready
> BEDBUG:ready
>
> => tftpboot 400000 p1
> ENET Speed is 100 Mbps - FULL duplex connection
> ARP broadcast 1
> TFTP from server 192.168.1.11; our IP address is
> 192.168.1.111 Filename 'p1'. Load address: 0x400000
> Loading:
> #################################################################
>          ############################################
> done
> Bytes transferred = 557872 (88330 hex)
> => imi 400000
>
> ## Checking Image at 00400000 ...
>    Image Name:   Linux-2.4.20-pre11
>    Created:      2002-10-31  12:17:56 UTC
>    Image Type:   PowerPC Linux Kernel Image (gzip compressed)
>    Data Size:    557808 Bytes = 544.7 kB
>    Load Address: 00000000
>    Entry Point:  00000000
>    Verifying Checksum ... OK
> => bootm 400000
> ## Booting image at 00400000 ...
>    Image Name:   Linux-2.4.20-pre11
>    Created:      2002-10-31  12:17:56 UTC
>    Image Type:   PowerPC Linux Kernel Image (gzip compressed)
>    Data Size:    557808 Bytes = 544.7 kB
>    Load Address: 00000000
>    Entry Point:  00000000
>    Verifying Checksum ... OK
>    Uncompressing Kernel Image ... OK
> Linux version 2.4.20-pre11 (root@tbdev1) (gcc version 2.95.4
> 20010319 (prerelease/franzo/20011204)) #12 Thu Oct 31
> 05:13:53 MST 2002 IBM Walnut port (C) 2000-2002 MontaVista
> Software, Inc. (source@mvista.com) On node 0 totalpages: 1295
> zone(0): 1295 pages.
> zone(1): 0 pages.
> zone(2): 0 pages.
> Kernel command line: console=ttyS0,9600 root=/dev/ram
> Warning: real time clock seems stuck!
>
>
>
> then nothing after that.
>
> Any ideas? I've searched the archives for walnut boot
> problems. It seems like most people just get it running and
> that's that.
>
> Thanks
> Craig
>
>


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Re: Real time clock seems stuck

[Wolfgang Denk]

In message <C6D44AA99ECEB540A5498F15F92DA07D228E3C@amperion01.amperion.com> you wrote:
>
> You may be loading the code too low.  See the comments for the
> CFG_BOOTMAPSZ parameter in CONFIG_WALNUT405.h and cmd_bootm.c.  Try
> loading at 0x800000 instead.

No; loading at 400000 (= 4 MB) leaves enough room for the  kernel  to
uncompress; also, the kernel is booting fine until it get's stuck.

> > Kernel command line: console=ttyS0,9600 root=/dev/ram
> > Warning: real time clock seems stuck!

This is a common problem on boards that don't have a RTC at  all,  or
only  one which becomes available only later during the boot process,
for example after loading the I2C drivers.

You can find a fix in rev. 1.6 of kernel/time.c in the  2.4.4  source
tree  on  our  CVS  server;  here is the relevant pert (omitting many
lines  that  only  contain  white  space  changes  due  to   changing
indentation):


Index: kernel/time.c
===================================================================
RCS file: /cvsroot/linux-2.4/arch/ppc/kernel/time.c,v
retrieving revision 1.5
retrieving revision 1.6
diff -u -w -r1.5 -r1.6
--- kernel/time.c       16 Apr 2001 19:29:07 -0000      1.5
+++ kernel/time.c       11 Jun 2002 22:05:26 -0000      1.6
@@ -310,6 +310,7 @@
         * makes things more complex. Repeatedly read the RTC until the
         * next second boundary to try to achieve some precision...
         */
+       if (ppc_md.get_rtc_time) {
        stamp = get_native_tbl();
        sec = ppc_md.get_rtc_time();
        elapsed = 0;
@@ -331,6 +332,8 @@
        /* No update now, we just read the time from the RTC ! */
        last_rtc_update = xtime.tv_sec;
        write_unlock_irqrestore(&xtime_lock, flags);
+       }
+
        /* Not exact, but the timer interrupt takes care of this */
        set_dec(tb_ticks_per_jiffy);


Then make sure that your board sets ppc_md.get_rtc_time to NULL.

Best regards,

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
Am I your nanny? The kernel is there to support  user  programs,  but
it's a _resource_ handler, not a baby feeder.     - Linus Torvalds in
      <Pine.LNX.3.91.960425074845.22041C-100000@linux.cs.Helsinki.FI>

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

Re: Real time clock seems stuck

[Kurt Wall]

Speaking on condition of anonymity, Dr. Craig Hollabaugh told us:
>
> Folks,
>
> I'm trying to get a walnut board booted. I'm using linuxppc_2_4_devel pulled from denx yesterday. I'm getting the "Real time clock seems stuck" message then nothing, no messages after that. I found a brief thread about this.
>

I've seen this on boards that don't have an RTC...

Kurt
--
"I take Him shopping with me. I say, 'OK, Jesus, help me find a bargain'"
--Tammy Faye Bakker

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

RE: Real time clock seems stuck

[Wright, David]

> -----Original Message-----
> From: Kurt Wall [mailto:kurt.wall@timesys.com]
> Sent: Thursday, October 31, 2002 9:28 AM
> To: linuxppc-embedded@lists.linuxppc.org
> Subject: Re: Real time clock seems stuck
>
>
>
> Speaking on condition of anonymity, Dr. Craig Hollabaugh told us:
> >
> > Folks,
> >
> > I'm trying to get a walnut board booted. I'm using
> linuxppc_2_4_devel pulled from denx yesterday. I'm getting
> the "Real time clock seems stuck" message then nothing, no
> messages after that. I found a brief thread about this.
> >
>
> I've seen this on boards that don't have an RTC...

He said he's working on a Walnut, guys, and a Walnut has a DS1743
RTC chip on board, or at least mine does.

The problem here is arising because the kernel is attempting to
probe the RTC continuously, waiting for it to tick over.  You
can't do that to a DS1743; you have to leave it idle for 500 usec
between probes or the indicators won't advance.

This isn't a production-quality patch, but here's the change I
made to arch/ppc/kernel/time.c:time_init() to handle the problem
(my changes tagged with "INFINISWITCH"):

	if (ppc_md.get_rtc_time) {
		int read_delta = 0;	/* INFINISWITCH */

		stamp = get_native_tbl();
		sec = ppc_md.get_rtc_time();
		elapsed = 0;
		do {
			old_stamp = stamp;
			old_sec = sec;
			stamp = get_native_tbl();
			if (__USE_RTC() && stamp < old_stamp) old_stamp -= 1000000000;
			elapsed += stamp - old_stamp;
			read_delta += stamp - old_stamp;  /* INFINISWITCH */

			/* some real-time clocks, like the DS1743, can't be
			 * read repeatedly at very high speed.  Only try to
			 * read the RTC once per jiffy (INFINISWITCH)
			 */
			if (read_delta > tb_ticks_per_jiffy) {
				sec = ppc_md.get_rtc_time();
				read_delta = 0;
			}
		} while ( sec == old_sec && elapsed < 2*HZ*tb_ticks_per_jiffy);



  -- David Wright, Infiniswitch Corp., Westborough, MA

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