linux-kernel - Re: [PATCH v2 02/19] ARM: at91/at91x40: remove use of at91_sys

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Date:	Thu, 23 Feb 2012 20:23:48 +1100
From:	Ryan Mallon <rmallon@...il.com>
To:	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
CC:	Nicolas Ferre <nicolas.ferre@...el.com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux@....linux.org.uk
Subject: Re: [PATCH v2 02/19] ARM: at91/at91x40: remove use of at91_sys_read/write

On 23/02/12 17:01, Jean-Christophe PLAGNIOL-VILLARD wrote:

> On 14:59 Thu 23 Feb     , Ryan Mallon wrote:
>> On 23/02/12 14:25, Jean-Christophe PLAGNIOL-VILLARD wrote:
>>
>>> On 09:22 Thu 23 Feb     , Ryan Mallon wrote:
>>>> On 22/02/12 20:39, Nicolas Ferre wrote:
>>>>
>>>>> From: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
>>>>>
>>>>> Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
>>>>> Acked-by: Nicolas Ferre <nicolas.ferre@...el.com>
>>>>> ---
>>>>>  arch/arm/mach-at91/at91x40.c              |    2 +-
>>>>>  arch/arm/mach-at91/at91x40_time.c         |   28 +++++++++++++++++-----------
>>>>>  arch/arm/mach-at91/include/mach/at91x40.h |   18 +++++++++---------
>>>>>  3 files changed, 27 insertions(+), 21 deletions(-)
>>>>>
>>>>> diff --git a/arch/arm/mach-at91/at91x40.c b/arch/arm/mach-at91/at91x40.c
>>>>> index 0154b7f..5400a1d 100644
>>>>> --- a/arch/arm/mach-at91/at91x40.c
>>>>> +++ b/arch/arm/mach-at91/at91x40.c
>>>>> @@ -44,7 +44,7 @@ static void at91x40_idle(void)
>>>>>  	 * Disable the processor clock.  The processor will be automatically
>>>>>  	 * re-enabled by an interrupt or by a reset.
>>>>>  	 */
>>>>> -	at91_sys_write(AT91_PS_CR, AT91_PS_CR_CPU);
>>>>> +	__raw_writel(AT91_PS_CR_CPU, AT91_PS_CR);
>>>>
>>>>
>>>> This doesn't seem to be equivalent, at91_sys_write does:
>>>>
>>>>   void __iomem *addr = (void __iomem *)AT91_VA_BASE_SYS;
>>>>   __raw_writel(value, addr + reg_offset);
>>>>
>>>> and this patch doesn't redefine AT91_PS_CR. Was it broken before this
>>>> patch? What am I missing?
>>> this is right
>>> #define AT91_PS_CR      (AT91_PS + 0)   /* PS Control register */
>>
>>
>> That doesn't answer my question.
>>
>> The old, at91_sys_write, version was writing to (using __raw_writel):
>>
>>   AT91_VA_BASE_SYS + AT91_PS_CR
>>
>> The new version is writing, also using __raw_writel, to:
>>
>>   AT91_PS_CR
>>
>> The value of AT91_PS_CR is not changed in this patch. Assuming that
>> AT91_VA_BASE_SYS for at91x40 (which at a quick glance it is not), then
>> the old and the new version of the code are not writing to the same
>> address.
>>
>> Was it previously incorrect, or is it incorrect now?
> it's as we update
> 
> +#define AT91_PS		0xffff4000	/* Power Save */


Ah, I missed the new value of AT91_PS. Sorry for the confusion.

~Ryan
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