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Tue, 16 Mar 2021 06:06:45 -0500 Received: from localhost (ileax41-snat.itg.ti.com [10.172.224.153]) by fllv0039.itg.ti.com (8.15.2/8.15.2) with ESMTP id 12GB6jDw069694; Tue, 16 Mar 2021 06:06:45 -0500 Date: Tue, 16 Mar 2021 16:36:44 +0530 From: Pratyush Yadav To: Michael Walle CC: , , Tudor Ambarus , Miquel Raynal , Richard Weinberger , Vignesh Raghavendra Subject: Re: [RFC PATCH 1/3] mtd: spi-nor: sfdp: remember sfdp_size Message-ID: <20210316110642.xvn4sohgkdq2ci7x@ti.com> References: <20210312190548.6954-1-michael@walle.cc> <20210312190548.6954-2-michael@walle.cc> <20210316104223.42tdob3uwjxc5vdz@ti.com> <065642fa4d4282d3d16e1d4f4c176ce8@walle.cc> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <065642fa4d4282d3d16e1d4f4c176ce8@walle.cc> User-Agent: NeoMutt/20171215 X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > > > --- > > > 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. -- Regards, Pratyush Yadav Texas Instruments Inc.