Re: [PATCH v15 6/8] mtd: spi-nor: Retain nor->addr_width at 4BAIT parse

Takahiro Kuwano
2022-05-13T01:27:46Z

On 5/13/2022 7:14 AM, Michael Walle wrote:
> Am 2022-05-10 00:10, schrieb tkuw584924@gmail.com:
>> From: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>
>>
>> In 4BAIT parse, keep nor->params->addr_width because it may be used as
>> current address mode in SMPT parse later on.
>
> Mh I'm not sure this is needed at all.
>
> SFDP spec says
>   Variable address length (the current setting of the address
>   length mode defines the address length)
>
> and
>   When the length is defined as variable, the software or hardware
>   controlling the memory is aware of the address length mode last
>   set in the memory device and this same length of address.
>
> We don't set any address mode until all the SFDP parsing is
> over. Therefore we should always be in 3 byte mode, no?
>
Actually there are some devices that have variable address length but
4 byte mode by default (I will work on those devices after this series
is settled). To support such case, I prefer to use params->addr_nbytes
as current address mode so that I can fix it in post_bfpt_fixup() hook.

Thanks,
Takahiro