[PATCH 2/2] mtd: spi-nor: Mask out fast read if not requested in DT

[Bin Meng]

The DT bindings of "jedec,spi-nor" [1] defines "m25p,fast-read" property
to indicate that "fast read" opcode can be used to read data from the
chip instead of the usual "read" opcode.

If this property is not present in DT, mask out fast read in
spi_nor_init_params(). This change mirrors the same logic in
spi_nor_info_init_params() in drivers/mtd/spi-nor/core.c in
the Linux kernel v5.14-rc3.

[1] Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml in the kernel tree

Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
---

 drivers/mtd/spi/spi-nor-core.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index 2883d092fc..d6a0ed39c5 100644
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -2597,6 +2597,8 @@ static int spi_nor_init_params(struct spi_nor *nor,
 			       const struct flash_info *info,
 			       struct spi_nor_flash_parameter *params)
 {
+	struct spi_slave *spi = nor->spi;
+
 	/* Set legacy flash parameters as default. */
 	memset(params, 0, sizeof(*params));
 
@@ -2604,18 +2606,25 @@ static int spi_nor_init_params(struct spi_nor *nor,
 	params->size = info->sector_size * info->n_sectors;
 	params->page_size = info->page_size;
 
+	if (!(info->flags & SPI_NOR_NO_FR)) {
+		/* Default to Fast Read for DT and non-DT platform devices. */
+		params->hwcaps.mask |= SNOR_HWCAPS_READ_FAST;
+
+		/* Mask out Fast Read if not requested at DT instantiation. */
+		if (!ofnode_read_bool(dev_ofnode(spi->dev), "m25p,fast-read"))
+			params->hwcaps.mask &= ~SNOR_HWCAPS_READ_FAST;
+	}
+
 	/* (Fast) Read settings. */
 	params->hwcaps.mask |= SNOR_HWCAPS_READ;
 	spi_nor_set_read_settings(&params->reads[SNOR_CMD_READ],
 				  0, 0, SPINOR_OP_READ,
 				  SNOR_PROTO_1_1_1);
 
-	if (!(info->flags & SPI_NOR_NO_FR)) {
-		params->hwcaps.mask |= SNOR_HWCAPS_READ_FAST;
+	if (params->hwcaps.mask & SNOR_HWCAPS_READ_FAST)
 		spi_nor_set_read_settings(&params->reads[SNOR_CMD_READ_FAST],
 					  0, 8, SPINOR_OP_READ_FAST,
 					  SNOR_PROTO_1_1_1);
-	}
 
 	if (info->flags & SPI_NOR_DUAL_READ) {
 		params->hwcaps.mask |= SNOR_HWCAPS_READ_1_1_2;
-- 
2.25.1