Re: [PATCH v2 05/35] mtd: spi-nor: Introduce Manufacturer ID collisions driver

On 8/24/21 1:47 AM, Michael Walle wrote:

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Am 2021-07-27 06:51, schrieb Tudor Ambarus:

quoted

Some manufacturers completely ignore the manufacturer's identification
code
standard (JEP106) and do not define the manufacturer ID continuation
scheme. This will result in manufacturer ID collisions.

An an example, JEP106BA requires Boya that it's manufacturer ID to be
preceded by 8 continuation codes. Boya's identification code must be:
0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0x68. But Boya ignores
the
continuation scheme and its ID collides with the manufacturer defined
in
bank one: Convex Computer.

Introduce the manuf-id-collisions driver in order to address ID
collisions
between manufacturers. flash_info entries will be added in a first
come,
first served manner. Differentiation between flashes will be done at
runtime if possible. Where runtime differentiation is not possible, new
compatibles will be introduced, but this will be done as a last resort.
Every new flash addition that define the SFDP tables, should dump its
SFDP
tables in the patch's comment section below the --- line, so that we
can
reference it in case of collisions.

Signed-off-by: Tudor Ambarus <redacted>
---
 drivers/mtd/spi-nor/Makefile              |  1 +
 drivers/mtd/spi-nor/core.c                |  1 +
 drivers/mtd/spi-nor/core.h                |  1 +
 drivers/mtd/spi-nor/manuf-id-collisions.c | 22 ++++++++++++++++++++++
 4 files changed, 25 insertions(+)
 create mode 100644 drivers/mtd/spi-nor/manuf-id-collisions.c

diff --git a/drivers/mtd/spi-nor/Makefile

b/drivers/mtd/spi-nor/Makefile
index 6b904e439372..48763d10daad 100644

--- a/drivers/mtd/spi-nor/Makefile
+++ b/drivers/mtd/spi-nor/Makefile

@@ -1,6 +1,7 @@

 # SPDX-License-Identifier: GPL-2.0

 spi-nor-objs                 := core.o sfdp.o swp.o otp.o sysfs.o
+spi-nor-objs                 += manuf-id-collisions.o
 spi-nor-objs                 += atmel.o
 spi-nor-objs                 += catalyst.o
 spi-nor-objs                 += eon.o

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 1a278d33b02d..d30c8f350dc1 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c

@@ -1829,6 +1829,7 @@ int spi_nor_sr2_bit7_quad_enable(struct spi_nor

*nor)
 }

 static const struct spi_nor_manufacturer *manufacturers[] = {
+     &spi_nor_manuf_id_collisions,

Intentionally at the beginning of all the flashes? So these

yes

might take precedence over "normal" ones? Shouldn't it be

yes

the other way around?

It doesn't really matter, either way we should correctly identify the flash.
I thought of putting the collisions driver first for better test coverage.
In case we miss a collision between a (future) entry from the manufacturer
collisions driver and one from a dedicated manufacturer driver, to hit the
flash entry from the collisions driver, which will report a wrong name for
the flash in the dedicated manufacturer driver. People will report that
something's wrong and we can fix the things sooner.

quoted

      &spi_nor_atmel,
      &spi_nor_catalyst,
      &spi_nor_eon,

diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index 55fceb0ec894..e9896cd60695 100644
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h

@@ -476,6 +476,7 @@ struct sfdp {

 };

 /* Manufacturer drivers. */
+extern const struct spi_nor_manufacturer spi_nor_manuf_id_collisions;
 extern const struct spi_nor_manufacturer spi_nor_atmel;
 extern const struct spi_nor_manufacturer spi_nor_catalyst;
 extern const struct spi_nor_manufacturer spi_nor_eon;

diff --git a/drivers/mtd/spi-nor/manuf-id-collisions.c

b/drivers/mtd/spi-nor/manuf-id-collisions.c
new file mode 100644
index 000000000000..bf7dba34f018

--- /dev/null
+++ b/drivers/mtd/spi-nor/manuf-id-collisions.c

@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Used to handle collisions between manufacturers, where

manufacturers are
+ * ignorant enough to not implement the ID continuation scheme
described in the
+ * JEP106 JEDEC standard.
+ */
+
+#include <linux/mtd/spi-nor.h>
+#include "core.h"
+
+static const struct flash_info id_collision_parts[] = {
+     /* Boya */
+     { "by25q128as", INFO(0x684018, 0, 64 * 1024, 256, SPI_NOR_SKIP_SFDP |
+                          SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ |
+                          SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB) },
+};
+
+const struct spi_nor_manufacturer spi_nor_manuf_id_collisions = {
+     .name = "manufacturer ID collisions",

mhh, so we loose the manufacturer name. Doh. Can we do better?

yes, we can introduce a const char *manufacturer_name in struct spi_nor and
update it with the correct manufacturer name. Will do.

cheers,
ta

-michael

quoted

+     .parts = id_collision_parts,
+     .nparts = ARRAY_SIZE(id_collision_parts),
+};

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