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-rw-r--r--drivers/mtd/spi-nor/spi-nor.c14
-rw-r--r--include/linux/mtd/spi-nor.h2
2 files changed, 16 insertions, 0 deletions
diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 9363f29..494b7a2 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -284,6 +284,20 @@ static inline int set_4byte(struct spi_nor *nor, const struct flash_info *info,
if (need_wren)
write_disable(nor);
+ if (!status && !enable &&
+ JEDEC_MFR(info) == SNOR_MFR_WINBOND) {
+ /*
+ * On Winbond W25Q256FV, leaving 4byte mode causes
+ * the Extended Address Register to be set to 1, so all
+ * 3-byte-address reads come from the second 16M.
+ * We must clear the register to enable normal behavior.
+ */
+ write_enable(nor);
+ nor->cmd_buf[0] = 0;
+ nor->write_reg(nor, SPINOR_OP_WREAR, nor->cmd_buf, 1);
+ write_disable(nor);
+ }
+
return status;
default:
/* Spansion style */
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index de36969..e60da0d 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -62,6 +62,8 @@
#define SPINOR_OP_RDCR 0x35 /* Read configuration register */
#define SPINOR_OP_RDFSR 0x70 /* Read flag status register */
#define SPINOR_OP_CLFSR 0x50 /* Clear flag status register */
+#define SPINOR_OP_RDEAR 0xc8 /* Read Extended Address Register */
+#define SPINOR_OP_WREAR 0xc5 /* Write Extended Address Register */
/* 4-byte address opcodes - used on Spansion and some Macronix flashes. */
#define SPINOR_OP_READ_4B 0x13 /* Read data bytes (low frequency) */
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