From: Albert ARIBAUD <albert.u.boot@aribaud.net>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH 3/9] arm: Move CP15 init out of cpu_init_crit()
Date: Thu, 27 Oct 2011 22:05:38 +0200 [thread overview]
Message-ID: <4EA9B992.909@aribaud.net> (raw)
In-Reply-To: <CAPnjgZ06BVaDDvaMiuaa59hTBL=d-ido1aBH7v=q7XMakcEfcg@mail.gmail.com>
Hi Simon,
Le 25/10/2011 23:16, Simon Glass a ?crit :
>> But please think about what you actually want in start.S. Do you
>> really want an #ifdef TEGRA2 with a check of a SOC register, followed
>> by a branch around the cp15_init code?
>
> ^^^^
> This is the bit we need to sort out.
Indeed, but I dont want a '#ifdef TEGRA2'. In the worst case I want a
'if (!core_is_avp())' by way of an identification register, and in the
best case, I just want cp15 to be set unconditionally.
>>>>> According to ARM, coprocessors 14 and 15 should always be supported from
>>>>> ARMv6 up. Are you sure the AVP does not have it? If there is a Tegra
>>>>> specification available, I'd like to have a look at it.
>>>>
>>>> Sorry I meant caches/MMU, etc. I should try doing the CP15 cache/MMU
>>>> init on the AVP and see what happens.
>>>
>>> Please do check this. It may be that you can actually write to it from AVP
>>> even though it has no or not all expected effect; and if that is confirmed,
>>> then you don't have to separate the boot paths any more,
>>
>> Yes I'm tempted to go with this even if the ARM ARM is silent on the
>> matter. I will try it out today.
>
> Silly me of course it doesn't work - since if the CP15 doesn't have
> those features then you get undef instruction exception. Please see
> ^^^ above!
Are you stating a reasoning here or the results of an actual test? What
causes an undefined instruction exception is the absence of a
coprocessor to handle the instruction, not the presence of a coprocessor
which incidentally cannot perform all of what"s being asked.
> Regards,
> Simon
Amicalement,
--
Albert.
next prev parent reply other threads:[~2011-10-27 20:05 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-13 21:05 [U-Boot] [PATCH 0/9] tegra2: Tidy up boot path Simon Glass
2011-10-13 21:05 ` [U-Boot] [PATCH 1/9] tegra2: Add arch_cpu_init() to fire up Cortex-A9 Simon Glass
2011-10-13 22:52 ` Mike Frysinger
2011-10-13 23:18 ` Simon Glass
2011-10-13 23:34 ` Mike Frysinger
2011-10-14 0:47 ` Simon Glass
2011-10-13 21:05 ` [U-Boot] [PATCH 2/9] tegra2: Simplify tegra_start() boot path Simon Glass
2011-10-13 21:05 ` [U-Boot] [PATCH 3/9] arm: Move CP15 init out of cpu_init_crit() Simon Glass
2011-10-21 20:58 ` Albert ARIBAUD
2011-10-21 21:18 ` Simon Glass
2011-10-21 21:43 ` Albert ARIBAUD
2011-10-21 21:54 ` Simon Glass
2011-10-21 22:24 ` Albert ARIBAUD
2011-10-22 5:05 ` Simon Glass
2011-10-22 7:56 ` Albert ARIBAUD
2011-10-22 16:13 ` Simon Glass
2011-10-24 19:34 ` Simon Glass
2011-10-24 20:04 ` Albert ARIBAUD
2011-10-24 20:14 ` Simon Glass
2011-10-24 21:21 ` Albert ARIBAUD
2011-10-25 5:02 ` Simon Glass
2011-10-25 6:41 ` Albert ARIBAUD
2011-10-25 13:44 ` Simon Glass
2011-10-25 21:16 ` Simon Glass
2011-10-27 20:05 ` Albert ARIBAUD [this message]
2011-10-27 20:17 ` Simon Glass
2011-10-27 22:39 ` Albert ARIBAUD
2011-10-27 22:46 ` Simon Glass
2011-10-28 1:43 ` Simon Glass
2011-10-28 5:09 ` Albert ARIBAUD
2011-10-29 0:36 ` Simon Glass
2011-10-30 10:16 ` Albert ARIBAUD
2011-10-31 21:44 ` Simon Glass
2011-10-31 22:54 ` Tom Warren
2011-11-05 5:17 ` Simon Glass
2011-11-05 8:09 ` Albert ARIBAUD
2011-11-05 13:36 ` Simon Glass
2011-10-28 5:07 ` Albert ARIBAUD
2011-11-05 8:17 ` Albert ARIBAUD
2011-11-05 14:00 ` Simon Glass
2011-10-13 21:05 ` [U-Boot] [PATCH 4/9] tegra2: Enable instruction cache Simon Glass
2011-10-13 21:05 ` [U-Boot] [PATCH 5/9] tegra2: Remove unneeded boot code Simon Glass
2011-10-13 21:06 ` [U-Boot] [PATCH 6/9] tegra2: Remove unneeded config option Simon Glass
2011-10-13 21:06 ` [U-Boot] [PATCH 7/9] tegra2: Remove unused low-level Tegra2 UART code Simon Glass
2011-10-13 21:06 ` [U-Boot] [PATCH 8/9] tegra2: Remove unneeded 'dynamic ram size' message Simon Glass
2011-10-13 21:06 ` [U-Boot] [PATCH 9/9] tegra2: Don't use board pointer before it is set up Simon Glass
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