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From: Phil Elwell <phil@raspberrypi.com>
To: Alessandro Zummo <a.zummo@towertech.it>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	linux-rtc@vger.kernel.org
Subject: Question about PCF85063A invalid state
Date: Wed, 13 Oct 2021 10:48:48 +0100	[thread overview]
Message-ID: <3c6e4252-8271-c968-0bf9-83a23384ce01@raspberrypi.com> (raw)

Hi,

We're using the PCF85063A on our Compute Module 4 I/O board, and a number of 
users have experienced problems with invalid state after inserting a backup 
battery. So far the problem has been confined to EXT_TEST (bit 7 of CTRL_1) 
being set, but there are a number of registers for which the driver only 
modifies a subset of the bits.

I can think of a number of ways to clear this invalid state, none of which are 
difficult - force a software reset whenever certain bits of certain registers 
have certain values, always specifically force some bits to known values, etc. -
but are there any preferences or pitfalls to be aware of?

Thanks for your input,

Phil Elwell, Raspberry Pi

             reply	other threads:[~2021-10-13  9:49 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-13  9:48 Phil Elwell [this message]
2021-10-13 20:14 ` Question about PCF85063A invalid state Alexandre Belloni
2021-10-15  9:07   ` Phil Elwell

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