Re: [BUG] hwmon: (spd5118) resume fails -ENXIO on write protected hubs

Understood - thanks for explaining the page selection part, that makes sense. I'll blacklist it for now.

Appreciate you taking the time to get back to me on this!

Gabriel G

On Monday, August 17th, 2026 at 12:58 PM, Guenter Roeck <[email protected]> wrote:

> On 8/17/26 09:42, GG wrote:
> > Sorry - I should have searched the archives before sending my last email. I've since
> > found this from February, which is the same problem:
> >
> >    https://lore.kernel.org/linux-hwmon/[email protected]/
> >
> > And I missed the obvious clue sitting in my own boot log:
> >
> >    i801_smbus 0000:00:1f.4: SPD Write Disable is set
> >
> > So my kernel already knew. Apologies for the noise.
> >
> 
> Unfortunately that knowledge is not passed on to the spd5118 driver.
> 
> > One thing I'll mention in case it's useful: that series above has spd5118 refuse to
> > probe when writes are disabled. On my machine that would lose me two working
> > temperature sensors. Reads are completely fine here, I get correct temps,
> > and my temperature limits read back properly. It's only writing that fails.
> >
> > Happy to test anything on my hardware if it would help.
> >
> 
> That can not be done, as I mentioned in my other e-mail.
> 
> Problem is that accessing temperature sensor data on spd5118 compatible chips
> requires a write to select the correct chip page. If writes are disabled, and
> the BIOS selected a page other than page 0, temperature sensor data is not
> accessible. Since the BIOS can do whatever it wants and may have selected a
> different page after a suspend/resume sequence, one simply can not trust
> the status when the driver is loaded initially.
> 
> Guenter
> 
>