[PATCH v4 09/16] spi: cadence-quadspi: skip DDR PHY tuning for 2-byte-address ops (i2383)

[Santhosh Kumar K]

Erratum i2383 on AM654 locks the address phase in PHY DDR mode when a
2-byte column address is used. DDR PHY tuning must not be attempted for
such operations; non-PHY DDR usage is unaffected. [0]

Add CQSPI_NO_2BYTE_ADDR_PHY_DDR quirk and check it in
cqspi_am654_ospi_execute_tuning(). When the erratum applies, return 0
with read_op->max_freq cleared.

[0] https://www.ti.com/lit/er/sprz544c/sprz544c.pdf

Signed-off-by: Santhosh Kumar K <s-k6 at ti.com>
---
 drivers/spi/spi-cadence-quadspi.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
index 72768292a32b..22df5f3bdb96 100644
--- a/drivers/spi/spi-cadence-quadspi.c
+++ b/drivers/spi/spi-cadence-quadspi.c
@@ -49,6 +49,7 @@ static_assert(CQSPI_MAX_CHIPSELECT <= SPI_DEVICE_CS_CNT_MAX);
 #define CQSPI_DISABLE_RUNTIME_PM	BIT(10)
 #define CQSPI_NO_INDIRECT_MODE		BIT(11)
 #define CQSPI_HAS_WR_PROTECT		BIT(12)
+#define CQSPI_NO_2BYTE_ADDR_PHY_DDR	BIT(13)
 
 /* Capabilities */
 #define CQSPI_SUPPORTS_OCTAL		BIT(0)
@@ -3211,6 +3212,20 @@ static int cqspi_am654_ospi_execute_tuning(struct spi_mem *mem,
 		return -EOPNOTSUPP;
 	}
 
+	/*
+	 * Erratum i2383: in PHY DDR mode, a 2-byte column address locks up
+	 * the address phase. Skip DDR PHY tuning for such operations.
+	 */
+	if ((cqspi->ddata->quirks & CQSPI_NO_2BYTE_ADDR_PHY_DDR) &&
+	    read_op->addr.nbytes == 2 &&
+	    (read_op->cmd.dtr || read_op->addr.dtr || read_op->dummy.dtr ||
+	     read_op->data.dtr)) {
+		dev_dbg(dev,
+			"i2383: skipping DDR PHY tuning (2-byte address)\n");
+		read_op->max_freq = 0;
+		return 0;
+	}
+
 	if (write_op) {
 		/*
 		 * For NAND: write the calibration pattern to the page cache.
@@ -3852,7 +3867,7 @@ static const struct cqspi_driver_platdata k2g_qspi = {
 
 static const struct cqspi_driver_platdata am654_ospi = {
 	.hwcaps_mask = CQSPI_SUPPORTS_OCTAL | CQSPI_SUPPORTS_QUAD,
-	.quirks = CQSPI_NEEDS_WR_DELAY,
+	.quirks = CQSPI_NEEDS_WR_DELAY | CQSPI_NO_2BYTE_ADDR_PHY_DDR,
 	.execute_tuning = cqspi_am654_ospi_execute_tuning,
 };
 
-- 
2.34.1