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From: "Sverdlin, Alexander (Nokia - DE/Ulm)" <alexander.sverdlin@nokia.com>
To: "linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>
Cc: Vignesh Raghavendra <vigneshr@ti.com>,
	Tudor Ambarus <tudor.ambarus@microchip.com>,
	Richard Weinberger <richard@nod.at>,
	Marek Vasut <marek.vasut@gmail.com>,
	"Sverdlin,
	Alexander \(Nokia - DE/Ulm\)" <alexander.sverdlin@nokia.com>,
	Miquel Raynal <miquel.raynal@bootlin.com>,
	Brian Norris <computersforpeace@gmail.com>,
	David Woodhouse <dwmw2@infradead.org>
Subject: [PATCH] spi-nor: intel-spi: Whitelist 4B read commands
Date: Fri, 12 Jul 2019 12:14:39 +0000
Message-ID: <20190712121401.28578-1-alexander.sverdlin@nokia.com> (raw)

From: Alexander Sverdlin <alexander.sverdlin@nokia.com>

spi-nor.c issues 4B commands for some Flash chips bigger than 16Mbytes.
Xeon(R) D-1500 documentation mentions its Integrated PCH Logic supports
Flash chips up to 64Mbytes.
D-1500 Integrated PCH documenation however has inconsistencies regarding
FADDR register width and says nothing about particular commands issued
to support 64Mbytes of Flash.

Nevetheless the tests on Xeon(R) CPU D-1548 with 512Mbit Flash chips
Macronix MX25L51245G and Micron MT25QL512A showed that erase, write and
read operations work just fine after SPINOR_OP_READ_4B and
SPINOR_OP_READ_FAST_4B are white-listed (currently only
SPINOR_OP_READ_FAST_4B is used and only for Macronix).

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
---
 drivers/mtd/spi-nor/intel-spi.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/mtd/spi-nor/intel-spi.c b/drivers/mtd/spi-nor/intel-spi.c
index 1ccf23f..43e55a2e 100644
--- a/drivers/mtd/spi-nor/intel-spi.c
+++ b/drivers/mtd/spi-nor/intel-spi.c
@@ -621,6 +621,8 @@ static ssize_t intel_spi_read(struct spi_nor *nor, loff_t from, size_t len,
 	switch (nor->read_opcode) {
 	case SPINOR_OP_READ:
 	case SPINOR_OP_READ_FAST:
+	case SPINOR_OP_READ_4B:
+	case SPINOR_OP_READ_FAST_4B:
 		break;
 	default:
 		return -EINVAL;
-- 
2.4.6


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