From: Michael Walle <michael@walle.cc>
To: Pratyush Yadav <p.yadav@ti.com>
Cc: linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org,
Tudor Ambarus <tudor.ambarus@microchip.com>,
Miquel Raynal <miquel.raynal@bootlin.com>,
Richard Weinberger <richard@nod.at>,
Vignesh Raghavendra <vigneshr@ti.com>
Subject: Re: [RFC PATCH 1/3] mtd: spi-nor: sfdp: remember sfdp_size
Date: Tue, 16 Mar 2021 12:22:25 +0100 [thread overview]
Message-ID: <3deb91e2c9fc3f62ae6976cecae37bf3@walle.cc> (raw)
In-Reply-To: <20210316110642.xvn4sohgkdq2ci7x@ti.com>
Am 2021-03-16 12:06, schrieb Pratyush Yadav:
> On 16/03/21 12:01PM, Michael Walle wrote:
>> Hi Pratyush,
>>
>> Am 2021-03-16 11:42, schrieb Pratyush Yadav:
>> > On 12/03/21 08:05PM, Michael Walle wrote:
>> > > Save the sftp_size in the spi_nor struct so we can use it to dump the
>> > > SFDP table without parsing the headers again.
>> > >
>> > > Signed-off-by: Michael Walle <michael@walle.cc>
>> > > ---
>> > > drivers/mtd/spi-nor/sfdp.c | 12 ++++++++++++
>> > > include/linux/mtd/spi-nor.h | 1 +
>> > > 2 files changed, 13 insertions(+)
>> > >
>> > > diff --git a/drivers/mtd/spi-nor/sfdp.c b/drivers/mtd/spi-nor/sfdp.c
>> > > index 25142ec4737b..b1814afefc33 100644
>> > > --- a/drivers/mtd/spi-nor/sfdp.c
>> > > +++ b/drivers/mtd/spi-nor/sfdp.c
>> > > @@ -16,6 +16,7 @@
>> > > (((p)->parameter_table_pointer[2] << 16) | \
>> > > ((p)->parameter_table_pointer[1] << 8) | \
>> > > ((p)->parameter_table_pointer[0] << 0))
>> > > +#define SFDP_PARAM_HEADER_PARAM_LEN(p) ((p)->length * 4)
>> > >
>> > > #define SFDP_BFPT_ID 0xff00 /* Basic Flash Parameter Table */
>> > > #define SFDP_SECTOR_MAP_ID 0xff81 /* Sector Map Table */
>> > > @@ -1263,6 +1264,7 @@ int spi_nor_parse_sfdp(struct spi_nor *nor,
>> > > struct sfdp_parameter_header *param_headers = NULL;
>> > > struct sfdp_header header;
>> > > struct device *dev = nor->dev;
>> > > + size_t param_max_offset;
>> > > size_t psize;
>> > > int i, err;
>> > >
>> > > @@ -1285,6 +1287,9 @@ int spi_nor_parse_sfdp(struct spi_nor *nor,
>> > > bfpt_header->major != SFDP_JESD216_MAJOR)
>> > > return -EINVAL;
>> > >
>> > > + nor->sfdp_size = SFDP_PARAM_HEADER_PTP(bfpt_header) +
>> > > + SFDP_PARAM_HEADER_PARAM_LEN(bfpt_header);
>> > > +
>> > > /*
>> > > * Allocate memory then read all parameter headers with a single
>> > > * Read SFDP command. These parameter headers will actually be
>> > > parsed
>> > > @@ -1311,6 +1316,13 @@ int spi_nor_parse_sfdp(struct spi_nor *nor,
>> > > }
>> > > }
>> > >
>> > > + for (i = 0; i < header.nph; i++) {
>> > > + param_header = ¶m_headers[i];
>> > > + param_max_offset = SFDP_PARAM_HEADER_PTP(param_header) +
>> > > + SFDP_PARAM_HEADER_PARAM_LEN(param_header);
>> > > + nor->sfdp_size = max(nor->sfdp_size, param_max_offset);
>> > > + }
>> > > +
>> >
>> > I don't see any mention in the SFDP spec (JESD216D-01) that parameter
>> > tables have to be contiguous.
>>
>> ch. 6.1, fig.10 looks like all the headers come after the initial SFDP
>> header. If that wasn't the case, how would you find the headers then?
>>
>> Also ch. 6.3
>> """All subsequent parameter headers need to be contiguous and may be
>> specified..."""
>>
>> > In fact, it says that "Parameter tables
>> > may be located anywhere in the SFDP space. They do not need to
>> > immediately follow the parameter headers".
>>
>> The tables itself, yes, but not the headers for the tables.
>
> Yes, I was talking about the tables and not the headers. There might be
> holes in the SFDP space but I don't think it would be a problem.
Ah, ok. Well basically I'm assuming that the holes will returning some
sane values. Or you could dump the space together with a mask. But that
is overkill ;)
-michael
next prev parent reply other threads:[~2021-03-16 11:23 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-12 19:05 [RFC PATCH 1/3] mtd: spi-nor: support dumping sfdp tables Michael Walle
2021-03-12 19:05 ` [RFC PATCH 1/3] mtd: spi-nor: sfdp: remember sfdp_size Michael Walle
2021-03-16 10:42 ` Pratyush Yadav
2021-03-16 11:01 ` Michael Walle
2021-03-16 11:06 ` Pratyush Yadav
2021-03-16 11:22 ` Michael Walle [this message]
2021-03-12 19:05 ` [RFC PATCH 2/3] mtd: spi-nor: sfdp: fix spi_nor_read_sfdp() Michael Walle
2021-03-16 11:04 ` Pratyush Yadav
2021-03-16 11:15 ` Michael Walle
2021-03-16 13:15 ` Pratyush Yadav
2021-03-12 19:05 ` [RFC PATCH 3/3] mtd: spi-nor: add sysfs and SFDP support Michael Walle
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=3deb91e2c9fc3f62ae6976cecae37bf3@walle.cc \
--to=michael@walle.cc \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mtd@lists.infradead.org \
--cc=miquel.raynal@bootlin.com \
--cc=p.yadav@ti.com \
--cc=richard@nod.at \
--cc=tudor.ambarus@microchip.com \
--cc=vigneshr@ti.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).