[U-Boot] [PATCH v3 4/7] tegra: fdt: Add NAND controller binding and definitions

[Simon Glass]

Hi Scott,

On Tue, Apr 17, 2012 at 1:31 PM, Scott Wood <scottwood at freescale.com> wrote:
> On 04/17/2012 03:18 PM, Simon Glass wrote:
>> +Jim, who wrote the driver originally
>>
>> Hi Scott,
>>
>> On Tue, Apr 17, 2012 at 12:06 PM, Scott Wood <scottwood at freescale.com> wrote:
>>>> + - nvidia,page-data-bytes : Number of bytes in the data area
>>>> + - nvidia,page-spare-bytes : Number of bytes in spare area
>>>> +       spare area = skipped-spare-bytes + data-ecc-bytes + tag-bytes
>>>> +                     + tag-ecc-bytes
>>>
>>> Do you really need this stuff to be in the device tree?  You should be
>>> able to determine this information from the ID table.
>>
>> I suspect so - the driver originally had a lot of CONFIGs for this.
>> Maybe someone who wants to take it further could do this as part of
>> supporting ONFI?
>>
>> I will see if Jim Lin can take another look.
>
> You don't need ONFI to get the page/spare size out of the ID table.
>
> The generic NAND code should already be doing this for you (fills in
> mtd->writesize and mtd->oobsize).  If you need it during setup, we now
> have CONFIG_SYS_NAND_SELF_INIT that allows splitting up
> nand_scan_ident() from nand_scan_tail().

OK, sounds good. It should just need to be changed over to calculate
these values from the nand layer.

>
>>>> +Nvidia NAND Controller
>>>> +----------------------
>>>> +
>>>> +The device node for a NAND flash controller is as follows:
>>>> +
>>>> +Optional properties:
>>>> +
>>>> +nvidia,wp-gpios : GPIO of write-protect line, three cells in the format:
>>>> +             phandle, parameter, flags
>>>
>>> Doesn't the number of cells depend on the GPIO controller binding?
>>
>> Yes, but this is the binding Tegra uses.
>
> Still, it doesn't belong in the NAND binding.  Maybe a future chip wants
> to use this NAND binding but a different GPIO binding.  If nothing else,
> people tend to copy-and-paste such descriptions.  We've still got people
> adding bindings for Freescale devices saying interrupts are encoded as a
> pair of cells, even though the interrupt controller now uses four cells
> per interrupt.

OK I see - are you are saying that we should just say something like:

"nvidia,wp-gpios : GPIO of write-protect line, as defined by gpio bindings"

>
> -Scott
>

Regards,
Simon