Re: [PATCH] mtd: spi-nor: fix options for mx66l51235f

[Cédric Le Goater <clg@xxxxxxxx>]

[ ... ] 

> Ah, so the whole problem is, the ASpeed 2400 SPI NOR controller does
> memory-mapped read from the flash and that has some limitations when the
> flash is over 16 MiB in size -- it sends 3 byte standard opcodes with 4
> byte address ?

yes.

[ ... ]

> To simplify the situation, if the ASpeed 2400 SPI NOR controller tried
> reading the SPI flash past 16 MiB, it would also require that the flash
> is in EN4B mode, yes ?

yes.

[ ... ]

>> I start thinking about maybe adding an option to "jedec,spi-nor" DTS
>> binding like "enable-4byte-mode", so that we could get rid of our
>> local patch and just specify that option in the devicetree. The
>> option would force EN4B on the chip if it supports that mode. What do
>> you think? How do I do it if you approve? Send patches separately in
>> here and in the devicetree mailing list or cross-post both patches to
>> both lists?
> 
> That's an option. But what I think this is really about is a fact that
> we completely lack any way to negotiate limitations between the SPI NOR
> and the controller.

what about the hwcaps in spi_nor_scan() ? 

Thanks,

C.


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