spi: cadence-quadspi: Fix check condition for DTR ops

buswidth and dtr fields in spi_mem_op are only valid when the
corresponding spi_mem_op phase has a non-zero length. For example,
SPI NAND core doesn't set buswidth when using SPI_MEM_OP_NO_ADDR
phase.

Fix the dtr checks in set_protocol() and suppports_mem_op() to
ignore empty spi_mem_op phases, as checking for dtr field in
empty phase will result in false negatives.
Signed-off-by: Apurva Nandan <a-nandan@ti.com>
Link: https://lore.kernel.org/r/20210716232504.182-3-a-nandan@ti.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-cadence-quadspi.c

@@ -325,7 +325,15 @@ static int cqspi_set_protocol(struct cqspi_flash_pdata *f_pdata,
 	f_pdata->inst_width = CQSPI_INST_TYPE_SINGLE;
 	f_pdata->addr_width = CQSPI_INST_TYPE_SINGLE;
 	f_pdata->data_width = CQSPI_INST_TYPE_SINGLE;
-	f_pdata->dtr = op->data.dtr && op->cmd.dtr && op->addr.dtr;
+
+	/*
+	 * For an op to be DTR, cmd phase along with every other non-empty
+	 * phase should have dtr field set to 1. If an op phase has zero
+	 * nbytes, ignore its dtr field; otherwise, check its dtr field.
+	 */
+	f_pdata->dtr = op->cmd.dtr &&
+		       (!op->addr.nbytes || op->addr.dtr) &&
+		       (!op->data.nbytes || op->data.dtr);
 
 	switch (op->data.buswidth) {
 	case 0:
@@ -1228,8 +1236,15 @@ static bool cqspi_supports_mem_op(struct spi_mem *mem,
 {
 	bool all_true, all_false;
 
-	all_true = op->cmd.dtr && op->addr.dtr && op->dummy.dtr &&
-		   op->data.dtr;
+	/*
+	 * op->dummy.dtr is required for converting nbytes into ncycles.
+	 * Also, don't check the dtr field of the op phase having zero nbytes.
+	 */
+	all_true = op->cmd.dtr &&
+		   (!op->addr.nbytes || op->addr.dtr) &&
+		   (!op->dummy.nbytes || op->dummy.dtr) &&
+		   (!op->data.nbytes || op->data.dtr);
+
 	all_false = !op->cmd.dtr && !op->addr.dtr && !op->dummy.dtr &&
 		    !op->data.dtr;