Re: [PATCH v1 4/4] mtd: spi-nor: macronix: Add 1-4-4 DTR read support for MX66L1G45G

[Miquel Raynal <miquel.raynal@bootlin.com>]

On 22/10/2026 at 03:26:14 -07, Changhuang Liang <changhuang.liang@starfivetech.com> wrote:

> The MX66L1G45G supports the 1-4-4 DTR read mode. This flash uses 6
> dummy cycles by default in 1-4-4 DTR mode, but the kernel's SFDP
> parser does not derive any SNOR_HWCAPS_READ_1_4_4_DTR capability from
> the BFPT table, and 4BAIT only filters already-known capabilities.
> The exact number of dummy cycles is also not directly given in the
> SFDP tables.
>
> Therefore, implement late_init to initialize support for this opcode,
> configuring the read settings with the default 6 dummy cycles. When a
> 4BAIT table is present, SFDP parsing has already converted all read
> opcodes to their 4-byte variants and spi_nor_set_4byte_opcodes() is
> skipped later on, so select the 4-byte opcode in that case.
>
> The part also supports the 4-byte opcode set but its SFDP does not
> expose a 4BAIT table, so set SPI_NOR_4B_OPCODES like MX66L51235F
> (0xc2 0x20 0x1a) to let spi_nor_set_4byte_opcodes() pick the 4-byte
> variants, including 0xEE for 1-4-4 DTR.
>
> Add a dedicated fixup for the part (SNOR_ID 0xc2, 0x20, 0x1b) that
> keeps the existing QPP 4-byte post-SFDP fixup and additionally
> advertises the 1-4-4 DTR read capability in late_init.
>
> Signed-off-by: Changhuang Liang <changhuang.liang@starfivetech.com>

Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>

Maybe in your v2 you can add (as hinted in the documentation) traces of
a test run with the SFDP tables, proof that it works in this mode, etc.

Thanks,
Miquèl