From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <zajec5@gmail.com>
Subject: [PATCH] mtd: spi-nor: detect JEDEC incompatible w25q128 using 0x90
 command
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Some w25q128 chipsets don't support RDID (0x9f) command, they reply with
0xff-s only. To suppose such flashes fallback to the 0x90 command.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
---

--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -1227,6 +1227,18 @@ static const struct flash_info *spi_nor_
 	}
 	dev_err(nor->dev, "unrecognized JEDEC id bytes: %02x, %02x, %02x\n",
 		id[0], id[1], id[2]);
+
+	tmp = nor->read_reg(nor, 0x90, id, SPI_NOR_MAX_ID_LEN);
+	if (tmp < 0) {
+		dev_dbg(nor->dev, " error %d reading JEDEC ID\n", tmp);
+		return ERR_PTR(tmp);
+	}
+	dev_info(nor->dev, "using Read Manufacturer / Device ID command (0x%02x) returned %02x %02x\n",
+		 0x90, id[0x03], id[0x04]);
+	if (id[0x03] == 0xef && id[0x04] == 0x17) {
+		return spi_nor_match_id("w25q128");
+	}
+
 	return ERR_PTR(-ENODEV);
 }