linux-kernel - Re: [PATCH v2] powerpc 8xx: Fixing issue with CONFIG_PIN

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Message-ID: <52414682.3010608@c-s.fr>
Date:	Tue, 24 Sep 2013 10:00:02 +0200
From:	leroy christophe <christophe.leroy@....fr>
To:	Scott Wood <scottwood@...escale.com>
CC:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	Joakim Tjernlund <joakim.tjernlund@...nsmode.se>
Subject: Re: [PATCH v2] powerpc 8xx: Fixing issue with CONFIG_PIN_TLB


Le 20/09/2013 23:22, Scott Wood a écrit :
>>> The hardware wants to decrement; why fight it?
>> >I see your point.
>> >However it is not clear in the documentation if the decrement is done
>> >really after the update, or at xTLB interrupt. So I propose to still set
>> >the CTR ourself as described in the reference Manual and not assume that
>> >the HW decrements it.
> It says "every update" -- do you have any reason to believe that's
> wrong?  It could be tested...
>
>
Ok. I just test it,  and I observe the following: As we have set the 
RSV4x bit, the CPU sets Mx_CTR to a value below 0x1c after each update:
* After writing entry 0x1c, Mx_CTR has value 0x1b
* After writing entry 0x1d, Mx_CTR has value 0x18
* After writing entry 0x1e, Mx_CTR has value 0x19
* After writing entry 0x1f, Mx_CTR has value 0x1a

Indeed the first version of my patch was complete, only the description 
was not fully correct.
So, in order to minimise code churn, I will re-submit my initial patch 
with a modified description.

Christophe
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