Re: [PATCH v4 3/6] ARM: dts: dra7: add support for parallel NAND flash

[Roger Quadros <rogerq@ti.com>]

On 05/14/2014 11:25 AM, Roger Quadros wrote:
> Hi Pekon,
> 
> On 05/12/2014 12:05 PM, Gupta, Pekon wrote:
>>> From: Javier Martinez Canillas [mailto:javier@dowhile0.org]
>> [...]
>>
>>>> Newer platforms have upgraded version of GPMC engine which supports
>>>> BCH16 ECC scheme in hardware. Thus the GPMC address space was
>>>> expanded to include some extra registers required for BCH16 ECC [2].
>>>>
>>>>
>>>
>>> I see and did the GPMC register space became that big to need to map 8KB?
>>>
>>> Although the smallest unit for ioremap is PAGE_SIZE and using any of
>>> these reg sizes:
>>>
>>> reg = <0x6e000000 0x02d0>;
>>> reg = <0x6e000000 0x0400>;
>>> reg = <0x6e000000 0x1000>;
>>>
>>> in practice have the same effect, DTS should describe the hardware and
>>> not an implementation detail so I think that we should use only the
>>> register size that is defined in the TRM.
>>>
>> Yes, I agree with you.
>> I have fixed this in newer version of the patch and will be sending it soon.
>> But this series will only contain updates for new platforms with addition
>> of NAND node in DTS, so that this series is not stalled for any reason.
>> For fixing existing platform/boards DTS I'll send another series soon.
>>
>> For now, I'll use GPMC address-space size = 0x380 as it matches with
>> actual hardware and is working.
> 
> How did you get 0x380?
> 
> From DRA7 TRM, GPMC address range is 0x5000 0000 : 0x5000 02D0
> So the address-space size should be 0x2D4 (as last register@2D0 is 32-bits wide)

Sorry for the noise.
Just figured out that the register space is not numerically arranged in the TRM.

The last register is P GPMC_BCH_RESULT6_i
	0x5000  0308  +  (0x0000   0010  *  i)
	i = 0 to 7

So size should be 0x37C.

cheers,
-roger
 
> 
> For the ELM module it should be 4KB i.e. 0x1000
> 
> cheers,
> -roger
> 
>>>>
>>>> [1] http://www.ti.com/lit/gpn/am3359    (Section 7.4 to 7.4.5)
>>>>
>>>> [2] http://www.ti.com/lit/gpn/am3359    (Section 7.1 to 7.1.5)
>>>> (Though the AM335x address space mentions 0x368 as last address,
>>>>  it should be 0x378. I have raised documentation bug for it).
>>>>
>>>>
>>>> with regards, pekon
>>>
>>> Best regards,
>>> Javier
>>>
>>> [0]: http://lxr.free-electrons.com/source/arch/arm/mm/ioremap.c#L334
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> 

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