Re: [RFC PATCH] rtc: rtc-at91rm9200: manage IMR depending on revision

From: Douglas Gilbert
Date: Tue Apr 02 2013 - 11:33:22 EST


On 13-04-02 09:06 AM, Nicolas Ferre wrote:
Signed-off-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
---
Hi all,

The funny thing is that I was writing exactly the same code as Johan's
when he posted his series.

So, here is my single patch, with the comment about the readback stolen from
Johan's, but without the way to determine with IP is buggy and which one is
not...
After having dug the possibility to read the IP revision, I discovered that it
is not possible to use this information ("version" register offset changing
according to... IP version number: well done!).
In conclusion, I guess that the only way to determine if we need the workaround
is to use the DT.
One remark though: if we use the compatibility string for this purpose, I fear
that we would twist the meaning of this information: SoC using an
"atmel,at91sam9x5-rtc" compatible RTC will not necessarily be touched by the
"non responding IMR" bug: at91sam9n12 or upcoming sama5d3 are not affected for
instance, and we need to cling to "atmel,at91rm9200-rtc" for them...
I think that we can use this method for the moment and move to another
compatibility string later if it is needed.

Rather than have so many people working on rtc-at91rm9200.c,
how about someone bring its "RTT" sibling into the DT
world. I'm talking about drivers/rtc/rtc-at91sam9.c ...

Doug Gilbert

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