Re: [PATCH 1/4] MIPS: BMIPS: bcm7346: add nodes for NAND

[Florian Fainelli <f.fainelli-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On 26/06/15 06:54, Jaedon Shin wrote:
> 
>> On Jun 26, 2015, at 12:00 PM, Florian Fainelli <f.fainelli-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>>
>> Le 06/25/15 01:52, Jaedon Shin a écrit :
>>>
>>>> On Jun 25, 2015, at 4:32 AM, Florian Fainelli <f.fainelli-Re5JQEeQqe8@public.gmane.orgm> wrote:
>>>>
>>>> +Brian,
>>>>
>>>> On 23/06/15 23:08, Jaedon Shin wrote:
>>>>> Add NAND device nodes to BMIPS based BCM7346 platform.
>>>>>
>>>>> Signed-off-by: Jaedon Shin <jaedon.shin-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>>>> ---
>>>>
>>>> [snip]
>>>>
>>>>> +
>>>>> +&nand0 {
>>>>> +	status = "okay";
>>>>> +
>>>>> +	nandcs@1 {
>>>>> +		compatible = "brcm,nandcs";
>>>>> +		reg = <1>;
>>>>> +		nand-ecc-step-size = <512>;
>>>>> +		nand-ecc-strength = <8>;
>>>>> +		nand-on-flash-bbt;
>>>>> +
>>>>> +		#size-cells = <2>;
>>>>> +		#address-cells = <2>;
>>>>> +
>>>>> +		flash1.rootfs0@0 {
>>>>> +			reg = <0x0 0x0 0x0 0x80000000>;
>>>>> +		};
>>>>> +
>>>>> +		flash1.rootfs1@80000000 {
>>>>> +			reg = <0x0 0x80000000 0x0 0x80000000>;
>>>>> +		};
>>>>> +	};
>>>>> +};
>>>>
>>>> Should we create something like brcmnand-cs1-512-8 to reduce the amount
>>>> of duplication between DTS files?
>>>> -- 
>>>> Florian
>>>
>>> I Think that is not duplication.
>>>
>>> I have no reference boards, but this node is maybe explaining for hardware
>>> description of the BCM97346DBSMB reference board. The nodes are changed by
>>> EBI CS and ECC capabilities of NAND flash. I used brcmnand-cs2-512-4 and
>>> brcmnand-cs1-512-4 for others.
>>
> 
> The *others* means BCM7346 based set-top box of manufacturer. they are not
> bcm973XX{dbsmb,svmb} boards.

Understood.

> 
>> Then I am confused, your 4 patches add identical NAND flash chip
>> properties for 7346, 7358, 7360 and 7362: CS#1, 512 bytes of ECC step
>> size and 8 bits of ECC strength, am I missing something?
>> -- 
>> Florian
> 
> The mips based reference boards have postfix of DBSMB, SVMB, SFF and others.
> they have different properties of DDR, #CS, SPI-NOR, NOR, NAND. if we write
> the DT of bcm97346sff.dts, therefore it has different fields.
> 
> Then I expected that mips 40nm based SVMB type reference boards have the same
> properties. but, I don't have confidence. AISE I have no reference boards
> unfortunately. if you can contact with people who have reference board, would
> tell me information of #CS and NAND.

I agree with you that outside of reference boards, these flash settings
will vary, however, Broadcom reference boards tend to follow the same
design from one chip/board to another, so instead of replicating 4 times
the same DT snippet in Device Tree, we could come up with differerent
sets of include files which abstract commonly found NAND flash types and
properties. Code might talk better, so I will try to submit something
that illustrates what I have in mind.

Thanks!
-- 
Florian
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