From: "Vladislav D. Buzov" <vbuzov@ru•mvista.com>
To: Segher Boessenkool <segher@kernel•crashing.org>
Cc: linuxppc-dev list <linuxppc-dev@ozlabs•org>
Subject: Re: [RFC/PATCH] powerpc: MPC7450 L2 HW cache flush feature utilization
Date: Fri, 15 Jun 2007 12:55:45 +0400 [thread overview]
Message-ID: <46725411.3080002@ru.mvista.com> (raw)
In-Reply-To: <c6cd3a9fe7713f081354cca9b4306811@kernel.crashing.org>
Segher Boessenkool wrote:
>>>>> /* TODO: use HW flush assist when available */
>>>>
>>>> You want to get rid of this old comment though -- and
>>>> perhaps branch over the non-hardware-assisted cache
>>>> flushing code.
>>>
>>> Ok, I agree that the comment is obsolete now. Would you please explain
>>> why the branch over non-hardware-assisted code should be removed as
>>> well. Technically the cache is flushed and there is no need to use
>>> extra
>>> commands to fill and then re-flush the cache.
>>
>> I think Segher is saying that you can skip the manual invalidation too
>> (although he said "flushing", I think he really meant "invalidation"--
>> the manual flushing is already skipped).
>
> Erm yes.
>
>> If I'm reading the manual
>> correctly, L2HWF does the invalidation as well so both the manual
>> flushing and invalidation can be skipped.
>
> Yeah. Not that it really matters of course.
Hrm. I don't think that cache invalidation should be skipped. It is done
after _set_L2CR() explicitly disabled the cache, in part of cache
enabling procedure. Note that cache is flushed only if _set_L2CR() is
called for already enabled cache. So, to skip cache invalidation there
is a need to somehow track whether the cache has been
flushed/invalidated before disabling or not. Since the manual
invalidation does not break anything I think it is better to leave it as
is rather than overload a _set_L2CR() logic.
Vlad.
>
>
> Segher
>
next prev parent reply other threads:[~2007-06-15 8:56 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-06-13 10:19 [RFC/PATCH] powerpc: MPC7450 L2 HW cache flush feature utilization Vladislav Buzov
2007-06-14 13:56 ` Segher Boessenkool
2007-06-14 17:12 ` Vladislav Buzov
2007-06-14 22:26 ` Mark A. Greer
2007-06-15 8:16 ` Segher Boessenkool
2007-06-15 8:55 ` Vladislav D. Buzov [this message]
2007-06-15 9:01 ` Segher Boessenkool
2007-06-15 9:33 ` Vladislav D. Buzov
2007-06-15 10:44 ` Segher Boessenkool
2007-06-15 8:14 ` Segher Boessenkool
2007-06-15 8:42 ` Vladislav D. Buzov
2007-06-15 8:56 ` Segher Boessenkool
2007-06-15 21:20 ` Mark A. Greer
2007-06-15 22:14 ` Segher Boessenkool
2007-06-21 12:37 ` Benjamin Herrenschmidt
2007-06-22 15:22 ` Vladislav Buzov
2007-06-23 15:46 ` Segher Boessenkool
2007-06-25 14:09 ` Vladislav Buzov
2007-06-28 8:24 ` Segher Boessenkool
2007-06-28 9:13 ` Benjamin Herrenschmidt
2007-06-28 10:47 ` Vladislav Buzov
2007-06-28 11:09 ` Benjamin Herrenschmidt
2007-06-25 19:00 ` Vladislav Buzov
2007-06-28 8:35 ` Segher Boessenkool
2007-06-29 10:41 ` Vladislav Buzov
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