From: Andrey Borzenkov <arvidjaar@newmail.ru>
To: Jean Delvare <khali@linux-fr.org>
Subject: Re: [lm-sensors] 2.6.15: lm90 0-004c: Register 0x13 read failed (-1)
Date: Sun, 15 Jan 2006 22:12:30 +0300
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References: <200601142223.35838.arvidjaar@newmail.ru> <20060114222032.1c2ff252.khali@linux-fr.org> <200601150045.30942.arvidjaar@newmail.ru>
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On Sunday 15 January 2006 00:45, Andrey Borzenkov wrote:
> On Sunday 15 January 2006 00:20, Jean Delvare wrote:
> > Hi Andrey,
> >
> > > Vanilla 2.6.15 on Toshiba Portege 4000. I get constant messages in
> > > dmesg:
> > >
> > > i2c_adapter i2c-0: Error: command never completed
> > > lm90 0-004c: Register 0x1 read failed (-1)
> > > i2c_adapter i2c-0: Error: command never completed
> > > lm90 0-004c: Register 0x14 read failed (-1)
> > > i2c_adapter i2c-0: Error: command never completed
> > > lm90 0-004c: Register 0x8 read failed (-1)
> > > i2c_adapter i2c-0: Error: command never completed
> > > lm90 0-004c: Register 0x0 read failed (-1)
> > >
> > > for quite a number of registers. Apparently I can read sensors just
> > > fine still I am uneasy seeing those.
> >
> > Before 2.6.15, the lm90 driver did not handle read errors in any way,
> > so they were probably already there, you simply were not aware of it.
> > However, I guess that you already had the "command never completed"
> > errors? These come from the i2c-ali1535 bus driver.
>
> Before 2.6.15 I run Mandriva kernel 2.6.12-12mdk. I do not remember them
> but may be I just never actually looked in dmesg :)
>
> > It would be possible to add a retry-on-failure mechanism in the lm90
> > driver. However, the real problem is more likely in the i2c-ali1535
> > driver so fixing this one driver would be preferable.
> >
> > > eeprom-i2c-0-50
> > > Adapter: SMBus ALI1535 adapter at ef00
> > > Memory type:            SDR SDRAM DIMM
> > > Memory size (MB):       256
> > >
> > > adm1032-i2c-0-4c
> > > Adapter: SMBus ALI1535 adapter at ef00
> > > M/B Temp:    +43?C  (low  =   -65?C, high =  +127?C)
> > > CPU Temp:  +47.6?C  (low  = +43.0?C, high = +51.0?C)   ALARM
> > > M/B Crit:   +127?C  (hyst =  +122?C)
> > > CPU Crit:   +100?C  (hyst =   +95?C)
> >
> > Do you also have "command never completed" errors without an associated
> > error from the lm90 driver?
>
> yes, on boot.
>
> > This would suggest that the eeprom driver
> > too is triggering errors, which in turn would confirm that we need to
> > fix the i2c-ali1535 driver rather than adding a workaround to the lm90
> > driver.
> >
> > It looks like the i2c-ali1535 driver as it exists in the lm_sensors CVS
> > repository (for Linux 2.4 kernels) did receive a major change in March
> > 2005. These changes were supposed to "fix stability problems" (by
> > adding delay loops pretty much everywhere). They were never ported to
> > the Linux 2.6 version of the driver. Maybe we should try doing so now.
> >
> > This is a 400 lines patch, porting it won't be trivial, I am not
> > familiar with this driver myself and I don't have a chip to test my
> > changes on, so if someone else wants to take his/her chance, go. If
> > not, I'll do it.
> >
> > Andrey, will you be able to test a i2c-ali1535 patch if we come up with
> > one?
>
> Yes. Send me a patch (or give a link) and I'll try what I can do to port
> it. I ask if I have a question :)
>

Do you mean revision 1.21 with date: 2005/03/27 02:22:10;  author: mds? I 
checked and this one seems to be in current 2.6.15.1 kernel. I did not check 
if there were any omissions comparing with CVS but current kernel does 
contain and use ali1535_transaction() added by mentioned patch.

- -andrey
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