[i2c] PCF8563 doesn't pass validation check

[Laurent Pinchart]

On Wednesday 02 July 2008, Jean Delvare wrote:
> Hi Laurent,
> 
> On Wed, 2 Jul 2008 11:34:55 +0200, Laurent Pinchart wrote:
> > I'm having issues with the PCF8563 RTC chip.
> > 
> > The Linux driver tries to validate the chip by checking if the
> > BCD-coded time and date registers contain valid values.
> > 
> > When a low voltage condition is detected, the registers are not
> > guaranteed to contain valid values. Experimentation showed that
> > while the seconds, minutes, hours and day of the week registers
> > didn't cause any issue, the months register could get out of the
> > 01-12 range.
> > 
> > Has anyone experienced the same issue ?
> 
> This issue sounds familiar, I think Alessandro mentioned it to me a few
> weeks ago in private already.
> 
> > Would it be acceptable to remove the months register check ?
> 
> I think you should convert rtc-pcf8563 to a new-style i2c driver. Then
> the whole validation function becomes pointless and you can delete it.
> I guess that the PCF8563 chip is used in embedded designs with platform
> code to instantiate the I2C devices as needed, so it should work fine.
> Apparently some IXP4xx platforms already expect rtc-pcf8563 to be a
> new-style i2c driver... I'm curious if some ARM people have already
> converted the driver. Rod?

Isn't rtc-pcf8563 a new-style i2c driver already ?

> > I've contacted NXP to get more information about what the chip
> > guarantees and what it doesn't. I haven't had any answer yet but
> > I expect them to tell me there is no guarantee at all.

-- 
Laurent Pinchart
CSE Semaphore Belgium

Chaussee de Bruxelles, 732A
B-1410 Waterloo
Belgium

T +32 (2) 387 42 59
F +32 (2) 387 42 75
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