From: Scott Wood <scottwood@freescale•com>
To: Martyn Welch <martyn.welch@ge•com>
Cc: linuxppc-dev@lists•ozlabs.org
Subject: Re: [PATCH] PowerPC: Remove hardcoded BAT configuration of IMMR in CPM early debug console
Date: Tue, 01 Jun 2010 11:06:32 -0500 [thread overview]
Message-ID: <4C053008.50306@freescale.com> (raw)
In-Reply-To: <4C050E84.2010602@ge.com>
On 06/01/2010 08:43 AM, Martyn Welch wrote:
>>>> diff --git a/arch/powerpc/kernel/head_32.S
>>>> b/arch/powerpc/kernel/head_32.S
>>>> index e025e89..861cace 100644
>>>> --- a/arch/powerpc/kernel/head_32.S
>>>> +++ b/arch/powerpc/kernel/head_32.S
>>>> @@ -1194,12 +1194,13 @@ setup_disp_bat:
>>>> #endif /* CONFIG_BOOTX_TEXT */
>>>>
>>>> #ifdef CONFIG_PPC_EARLY_DEBUG_CPM
>>>> +#define PPC_EARLY_DEBUG_CPM_ADDR
>>>> ASM_CONST(CONFIG_PPC_EARLY_DEBUG_CPM_ADDR)
>>>> setup_cpm_bat:
>>>> - lis r8, 0xf000
>>>> + lis r8, PPC_EARLY_DEBUG_CPM_ADDR@ha
>>>> ori r8, r8, 0x002a
>>>> mtspr SPRN_DBAT1L, r8
>>>>
>>>> - lis r11, 0xf000
>>>> + lis r11, PPC_EARLY_DEBUG_CPM_ADDR@ha
>>>> ori r11, r11, (BL_1M<< 2) | 2
>>>> mtspr SPRN_DBAT1U, r11
>>>>
>>> Only the physical address should depend on where IMMR is. We should
>>> use fixmap instead of an arbitrary address for the effective address.
>>> There's a existing FIX_EARLY_DEBUG_BASE, but it's only 128 KiB so
>>> we'll have to either grow it, or map only a subset of IMMR.
>>>
>>>
>>
>> I think that's a more fundamental change to CPM early debug than I can
>> handle right now.
Is IMMRBASE on your board at some address that has a low likelihood of
conflicting when treated as a kernel effective address?
>>> Plus, CONFIG_PPC_EARLY_DEBUG_CPM_ADDR points to the TX descriptor, not
>>> to the beginning of IMMR, so you should mask off the lower 20 bits
>>> (the offset is probably less than 64K, and the BAT might just ignore
>>> the extra bits anyway, but why take chances?).
>>>
>>>
>>
>> I assume that an extra instruction "andi r8, r8, 0xfff0" after each
>> "lis" instruction would be what you are looking for?
>>
>>
> "andis" even.
"lis r8, (PPC_EARLY_DEBUG_CPM_ADDR & 0xfff00000)@h" should work too.
-Scott
next prev parent reply other threads:[~2010-06-01 16:06 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-28 15:18 [PATCH] PowerPC: Remove hardcoded BAT configuration of IMMR in CPM early debug console Martyn Welch
2010-05-28 16:18 ` Scott Wood
2010-05-29 3:37 ` Benjamin Herrenschmidt
2010-06-01 12:52 ` Martyn Welch
2010-06-01 13:43 ` Martyn Welch
2010-06-01 16:06 ` Scott Wood [this message]
2010-06-02 8:06 ` Martyn Welch
2010-06-02 16:28 ` Scott Wood
2010-06-03 9:12 ` Martyn Welch
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