From mboxrd@z Thu Jan  1 00:00:00 1970
From: ryan@bluewatersys.com (Ryan Mallon)
Date: Thu, 12 Aug 2010 08:43:06 +1200
Subject: [PATCH 2/5] SPEAR3xx: Rename register/irq defines to remove naming
	conflicts
In-Reply-To: <4C6269F0.8060109@st.com>
References: <1275717955-14545-1-git-send-email-ryan@bluewatersys.com>
	<1275717955-14545-3-git-send-email-ryan@bluewatersys.com>
	<4C60DFB8.20608@st.com> <4C61BB85.5050406@bluewatersys.com>
	<4C6269F0.8060109@st.com>
Message-ID: <4C630B5A.3030509@bluewatersys.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 08/11/2010 09:14 PM, viresh kumar wrote:
> On 8/11/2010 2:20 AM, Ryan Mallon wrote:
>>>>>>  
>>>>>> +/*
>>>>>> + * GPIO pins virtual irqs
>>>>>> + * Use the lowest number for the GPIO virtual IRQs base on which subarchs
>>>>>> + * we have compiled in
>>>>>> + */
>>>>>> +#if defined(CONFIG_MACH_SPEAR310)
>>>>>> +#define SPEAR_GPIO_INT_BASE			(SPEAR3XX_VIRQ_START + 18)
>>>>>> +#elif defined(CONFIG_MACH_SPEAR320)
>>>>>> +#define SPEAR_GPIO_INT_BASE			(SPEAR3XX_VIRQ_START + 17)
>>>>>> +#else
>>>>>> +#define SPEAR_GPIO_INT_BASE			(SPEAR3XX_VIRQ_START + 9)
>>>>>>  #endif
>>>>
>>>> If we have all three machines enabled, then SPEAR_GPIO_INT_BASE will start from
>>>> VIRQ_START + 18, which will work for spear310 and spear320, but will not be
>>>> correct as we will skip 9 irq no.s.
>> Do the virtual irqs map directly to the hardware in some way? I thought
>> that since they were virtual there offset would be somewhat arbitrary?
> 
> No. Virtual irqs are not fixed with hardware. What i wanted to say is
> NR_IRQS will have a higher value, which will make irq_desc[NR_IRQS]
> array have more size.

Right, but the ifdef code about will make sure that if you only compile
in a single Spear implementation then the VIRQ start will be optimal. If
you compile multiple Spear implementations in then you get the benefit
of a single kernel which boots on multiple boards, at the cost of some
minimal memory wastage in some cases.

~Ryan

>>
>>>> It would be better to have three different base addresses
>>>> SPEAR300_GPIO_INT_BASE, etc.
>> This is possible. We can either do this by making SPEAR3XX_GPIO_INT_BASE
>> a variable, or by having some ifdef/machine_is code in the board
>> initialisation.
> 
> Not sure! We need to have single value of NR_IRQS for all spear3xx variants.
> This will always waste some memory. I don't know if any other solution can
> be there.
> 
> So SPEAR_GPIO_INT_BASE can be kept common with a single value without
> these #ifdefs, i.e. we can have
> #define SPEAR_GPIO_INT_BASE			(SPEAR3XX_VIRQ_START + 18)
> 
> and now we can have different macros per machine, i.e. 300,310,320.
> 
> viresh.


-- 
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