[PATCH RFC] mtd: spi-nor: unset quad_enable if SFDP doesn't specify it

[Michael Walle]

For flashes which use the first JESD216 revision, we don't know
which enable method for quad mode we can use. The default one in
spi_nor_init_default_params() is wrong for at least the Macronix
MX25L12835F, thus clear the enable method. Flashes with such an
SFDP revision will have to use a flash (and SFDP revision)
specific fixup.

Signed-off-by: Michael Walle <michael at walle.cc>
---
Please note, completely, untested. Heiko, could you test this without
having the second series from Tudor applied? Then you should have at
least a working flash without quad mode.

 drivers/mtd/spi-nor/sfdp.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/sfdp.c b/drivers/mtd/spi-nor/sfdp.c
index a5211543d30d..c23e85274ff2 100644
--- a/drivers/mtd/spi-nor/sfdp.c
+++ b/drivers/mtd/spi-nor/sfdp.c
@@ -549,6 +549,14 @@ static int spi_nor_parse_bfpt(struct spi_nor *nor,
 	map->uniform_erase_type = map->uniform_region.offset &
 				  SNOR_ERASE_TYPE_MASK;
 
+	/*
+	 * The first JESD216 revision doesn't specify a method to enable
+	 * quad mode. spi_nor_init_default_params() will set a legacy
+	 * default method to enable quad mode. We have to disable it
+	 * again.
+	 */
+	params->quad_enable = NULL;
+
 	/* Stop here if not JESD216 rev A or later. */
 	if (bfpt_header->length == BFPT_DWORD_MAX_JESD216)
 		return spi_nor_post_bfpt_fixups(nor, bfpt_header, &bfpt);
@@ -562,7 +570,6 @@ static int spi_nor_parse_bfpt(struct spi_nor *nor,
 	/* Quad Enable Requirements. */
 	switch (bfpt.dwords[BFPT_DWORD(15)] & BFPT_DWORD15_QER_MASK) {
 	case BFPT_DWORD15_QER_NONE:
-		params->quad_enable = NULL;
 		break;
 
 	case BFPT_DWORD15_QER_SR2_BIT1_BUGGY:
-- 
2.30.2