linux-kernel - Re: [PATCH] ARM: proc: Add Krait proc info

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Date:	Tue, 05 Mar 2013 14:03:10 -0800
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Will Deacon <will.deacon@....com>
CC:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
	Stepan Moskovchenko <stepanm@...eaurora.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ARM: proc: Add Krait proc info

On 03/05/13 00:34, Will Deacon wrote:
> Hi Stephen, Stepan,
>
> On Mon, Mar 04, 2013 at 11:21:39PM +0000, Stephen Boyd wrote:
>> From: Stepan Moskovchenko <stepanm@...eaurora.org>
>>
>> Add processor info for the Qualcomm, Inc. Krait family of
>> processors, to use the generic ARMv7 initialisation
>> procedure but explicitly enable the IDIV hardware
>> capability flag.
>>
>> Signed-off-by: Stepan Moskovchenko <stepanm@...eaurora.org>
>> Signed-off-by: Stephen Boyd <sboyd@...eaurora.org>
>> ---
>>  arch/arm/mm/proc-v7.S |   10 ++++++++++
>>  1 file changed, 10 insertions(+)
>>
>> diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
>> index 3a3c015..81adeb3 100644
>> --- a/arch/arm/mm/proc-v7.S
>> +++ b/arch/arm/mm/proc-v7.S
>> @@ -434,6 +434,16 @@ __v7_ca15mp_proc_info:
>>  	.size	__v7_ca15mp_proc_info, . - __v7_ca15mp_proc_info
>>  
>>  	/*
>> +	 * Qualcomm Inc. Krait processors.
>> +	 */
>> +	.type	__krait_proc_info, #object
>> +__krait_proc_info:
>> +	.long	0x510f0400		@ Required ID value
>> +	.long	0xff0ffc00		@ Mask for ID
>> +	__v7_proc __v7_setup, hwcaps = HWCAP_IDIV
> I was looking at this the other day and wondered whether we could set
> HWCAP_IDIV in __v7_setup, depending on ID_ISAR0[27:24]. I can't immediately
> think why that would be difficult, but similarly there may well be a reason
> why we assign it like this.
>
> Fancy taking a look?

Ok I'll take a look. Should we be masking out HWCAP_IDIVT on
!CONFIG_ARM_THUMB configurations?

----8<-----

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 3f6cbb2..e2c8bbf 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -484,7 +484,7 @@ static void __init setup_processor(void)
                 list->elf_name, ENDIANNESS);
        elf_hwcap = list->elf_hwcap;
 #ifndef CONFIG_ARM_THUMB
-       elf_hwcap &= ~HWCAP_THUMB;
+       elf_hwcap &= ~(HWCAP_THUMB | HWCAP_IDIVT);
 #endif
 
        feat_v6_fixup();

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

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