[PATCH v10 19/19] mtd: spi-nor: reset max_read_op frequency for security register reads

[Santhosh Kumar K <s-k6@ti.com>]

spi_nor_otp_read_secr() temporarily overrides read_opcode, read_dummy,
and read_proto to issue the RSECR command in 1-1-1 mode, then restores
them afterwards. spi_nor_spimem_get_read_op() already refuses to
propagate the PHY-calibrated frequency onto an op whose protocol shape
no longer matches what was tuned, which covers this case: RSECR's
single-wire SDR shape never matches a tuned high-bandwidth protocol.

Reset max_read_op.max_freq around this call anyway, following the same
save/override/restore pattern already used for the other overridden
fields in this function. This keeps the security-register path's
safety self-evident at the call site, independent of the shape check
in spi_nor_spimem_get_read_op(), and keeps it correct even if that
check is later changed.

Signed-off-by: Santhosh Kumar K <s-k6@ti.com>
---
 drivers/mtd/spi-nor/otp.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/mtd/spi-nor/otp.c b/drivers/mtd/spi-nor/otp.c
index bb9a801b3ceb..9a25953f5ea0 100644
--- a/drivers/mtd/spi-nor/otp.c
+++ b/drivers/mtd/spi-nor/otp.c
@@ -39,6 +39,7 @@ int spi_nor_otp_read_secr(struct spi_nor *nor, loff_t addr, size_t len, u8 *buf)
 	u8 addr_nbytes, read_opcode, read_dummy;
 	struct spi_mem_dirmap_desc *rdesc;
 	enum spi_nor_protocol read_proto;
+	unsigned int max_read_op_freq;
 	int ret;
 
 	read_opcode = nor->read_opcode;
@@ -46,11 +47,14 @@ int spi_nor_otp_read_secr(struct spi_nor *nor, loff_t addr, size_t len, u8 *buf)
 	read_dummy = nor->read_dummy;
 	read_proto = nor->read_proto;
 	rdesc = nor->dirmap.rdesc;
+	max_read_op_freq = nor->max_read_op.max_freq;
 
 	nor->read_opcode = SPINOR_OP_RSECR;
 	nor->read_dummy = 8;
 	nor->read_proto = SNOR_PROTO_1_1_1;
 	nor->dirmap.rdesc = NULL;
+	/* Security register uses an untuned 1-1-1 protocol; force base rate. */
+	nor->max_read_op.max_freq = 0;
 
 	ret = spi_nor_read_data(nor, addr, len, buf);
 
@@ -59,6 +63,7 @@ int spi_nor_otp_read_secr(struct spi_nor *nor, loff_t addr, size_t len, u8 *buf)
 	nor->read_dummy = read_dummy;
 	nor->read_proto = read_proto;
 	nor->dirmap.rdesc = rdesc;
+	nor->max_read_op.max_freq = max_read_op_freq;
 
 	return ret;
 }
-- 
2.34.1