[PATCH v4 04/28] mtd: spi-nor: Unconditionally parse SFDP in the deprecated path

As of today, the deprecated initialization path only attempts to parse
the SFDP tables when the flash entry advertised a dual, quad or octal
read capability in ->no_sfdp_flags. This was initially a surprise to me
since the documentation and commit logs I read while searching the
history do not clearly explain why. It seems that this is some kind of
(double) legacy behavior since a change made it clear in 2021 that in
order to skip trying to parse SFDP in the deprecated path, chips should
be marked with SPI_NOR_SKIP_SFDP (in which case the deprecated path
mentioned in the title will not be attempted).

As a result of this situation, Winbond W25Q32JV-Q/N and W25Q64JV-M
chips, which feature good SFDP support, are using only the stale flags
in the ID table because of ID reuse. I tried to remove the stale entries
but this change got refused because it would break support for legacy
chips without SFDP support (until ~2016).

Parsing SFDP unconditionally seems safe:
spi_nor_sfdp_init_params_deprecated() already restores the legacy
parameters whenever parsing fails, so non-SFDP chips simply fall back to
their previous behavior. As stated above, anybody bisecting a SPI NOR
boot issue and getting to this commit should add (and contribute) the
SPI_NOR_SKIP_SFDP flag in their no_sfdp_flags field.

Signed-off-by: Miquel Raynal <[email protected]>
---
 drivers/mtd/spi-nor/core.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index c39c6833c9a4..b4d09f14fff7 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -3092,11 +3092,7 @@ static void spi_nor_init_params_deprecated(struct spi_nor *nor)
 
 	spi_nor_manufacturer_init_params(nor);
 
-	if (nor->info->no_sfdp_flags & (SPI_NOR_DUAL_READ |
-					SPI_NOR_QUAD_READ |
-					SPI_NOR_OCTAL_READ |
-					SPI_NOR_OCTAL_DTR_READ))
-		spi_nor_sfdp_init_params_deprecated(nor);
+	spi_nor_sfdp_init_params_deprecated(nor);
 }
 
 /**

-- 
2.54.0