[PATCH 3/3] mtd: rawnand: denali: Do not reset the block before booting the kernel

[Marek Vasut]

On 1/10/20 6:26 AM, Masahiro Yamada wrote:
> On Fri, Jan 10, 2020 at 1:05 PM Marek Vasut <marex at denx.de> wrote:
>>
>> On 1/10/20 4:09 AM, Masahiro Yamada wrote:
>>> On Fri, Jan 10, 2020 at 9:14 AM Marek Vasut <marex at denx.de> wrote:
>>>>
>>>> The Denali NAND block loses configuration when put in reset.
>>>> Specifically, RB_PIN_ENABLED, CHIP_ENABLE_DONT_CARE,
>>>> SPARE_AREA_SKIP_BYTES and SPARE_AREA_MARKER are lost.
>>>> Since mainline Linux depends on the configuration programmed
>>>> into the Denali NAND controller by the bootloader, do not
>>>> reset the controller before starting the kernel, otherwise
>>>> the kernel will read bogus values and fail to use the NAND.
>>>
>>> I think this log is not directly describing the issue.
>>> It is not a matter of reading bogus values.
>>> You cannot use the hardware under the reset state in the first place.
>>>
>>> How about describing the root cause?
>>> For example,
>>>
>>> The denali driver in the mainline Linux does not support the reset
>>> control yet. Do not reset the controller before starting the kernel,
>>> otherwise the kernel cannot deassert the reset of the NAND controller.
>>
>> Is this better?
> 
> I do not think so.
> 
> Most of the description is just redundant.
> 
> Hardware under the reset state does not work in any way.
> The mainline kernel cannot deassert the NAND controller reset by itself.
> That's all.

That's only applicable to current state of things.

Can you provide better description ? Note that on SoCFPGA, the behavior
is exactly as documented here. Maybe it's different on Socionext ?