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 <20220712163823.428126-4-sudip.mukherjee@sifive.com> <d918c4d3d91adac247ebae6418b409b7@walle.cc>
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From:   Sudip Mukherjee <sudip.mukherjee@sifive.com>
Date:   Mon, 18 Jul 2022 15:56:56 +0100
Message-ID: <CAHyZL-cUJ7Zu=r5ZGD3p4XY9Ypdc-YuaqbKmdHjYQfAT6Fu_fA@mail.gmail.com>
Subject: Re: [PATCH 3/3] mtd: spi-nor: issi: is25wp256: Enable Quad Input Page Program
To:     Michael Walle <michael@walle.cc>
Cc:     Tudor Ambarus <tudor.ambarus@microchip.com>,
        Pratyush Yadav <p.yadav@ti.com>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Greentime Hu <greentime.hu@sifive.com>,
        Jude Onyenegecha <jude.onyenegecha@sifive.com>,
        William Salmon <william.salmon@sifive.com>,
        Adnan Chowdhury <adnan.chowdhury@sifive.com>,
        Ben Dooks <ben.dooks@sifive.com>,
        linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org
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Hi Michael,

On Mon, Jul 18, 2022 at 8:39 AM Michael Walle <michael@walle.cc> wrote:
>
> Am 2022-07-12 18:38, schrieb Sudip Mukherjee:
> > The flash chip is25wp256 supports Quad Input Page Program. Enable it
> > in its no_sfdp_flags flags.
>
> Are you sure, that chip doesn't have SFDP? Even the oldest datasheet
> I've found [1] mention SFDP.

Yes, that is what I expected from the datasheet. But from the driver code,
spi_nor_init_params() is calling spi_nor_init_params_deprecated() as
'parse_sfdp' is not true.
and looking at issi_nor_parts[], I can see is25wp256 is not marked
with 'PARSE_SFDP' so it
will skip parsing SFDP. The same datasheet also has is25lp256 which is
marked with 'PARSE_SFDP'
in the driver.
I tried to add 'PARSE_SFDP' to is25wp256, and I can see its mostly
working but its not using
Quad Input Page Program. I guess this support was not discovered from SFDP.


--
Regards
Sudip