[PATCH] mtd: spi-nor: support eon en25qh256a variant

[Michael Walle]

Hi,

For the next time if you submit a new patch version: the subject should
contain v2, eg. [PATCH v2]. See 
Documentation/process/submitting-patches.rst.
Also a changelog would be good.

Am 2022-05-03 01:33, schrieb Leon M. George:
> This patch allows accessing the upper 16m on the A variant (EN25QH256A) 
> of
> the EN25QH256 that shares same JEDEC ID.
> 
> Without this patch, addr_with is detected to be '4' but the read_opcode 
> is
> a plain READ (supporting only 3 byte addresses).
> Setting PARSE_SFDP is enough to detect the read_opcode READ_4B on the A
> variant. READ_4B is not available on the no-A variant.
> 
> Both variants support 4-byte address mode (spi_nor_set_4byte_addr_mode)
> but that is prone to breaking on unexpected reboots if the reset pin 
> isn't
> connected (broken-flash-reset).
> 
> The no-A variant supports a 'high bank latch mode' that affects read,
> program, and erase commands - similar to the extended address register
> (EAR).
> The HBL bit is manipulated using the ENHBL (0x67) and EXHBL (0x98)
> opcodes.
> 
> Should it become necessary to distinguish the two variants in the 
> future,
> the A variant sets the SNOR_HWCAPS_READ_1_1_4 SFDP param - the no-A
> variant doesn't.
> 
> Tested with and without fast read on the A variant only.
> 
> Signed-off-by: Leon M. George <leon at georgemail.eu>

Reviewed-by: Michael Walle <michael at walle.cc>

-michael