[PATCH 4.9 049/134] spi: cadence-quadspi: Abort read if dummy cycles required are too many

[Greg Kroah-Hartman]

From: Pratyush Yadav <p.yadav@xxxxxx>

[ Upstream commit ceeda328edeeeeac7579e9dbf0610785a3b83d39 ]

The controller can only support up to 31 dummy cycles. If the command
requires more it falls back to using 31. This command is likely to fail
because the correct number of cycles are not waited upon. Rather than
silently issuing an incorrect command, fail loudly so the caller can get
a chance to find out the command can't be supported by the controller.

Fixes: 140623410536 ("mtd: spi-nor: Add driver for Cadence Quad SPI Flash Controller")
Signed-off-by: Pratyush Yadav <p.yadav@xxxxxx>
Link: https://lore.kernel.org/r/20201222184425.7028-3-p.yadav@xxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/mtd/spi-nor/cadence-quadspi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/cadence-quadspi.c b/drivers/mtd/spi-nor/cadence-quadspi.c
index d489fbd07c12b..92de2b408734a 100644
--- a/drivers/mtd/spi-nor/cadence-quadspi.c
+++ b/drivers/mtd/spi-nor/cadence-quadspi.c
@@ -461,7 +461,7 @@ static int cqspi_indirect_read_setup(struct spi_nor *nor,
 	/* Setup dummy clock cycles */
 	dummy_clk = nor->read_dummy;
 	if (dummy_clk > CQSPI_DUMMY_CLKS_MAX)
-		dummy_clk = CQSPI_DUMMY_CLKS_MAX;
+		return -EOPNOTSUPP;
 
 	if (dummy_clk / 8) {
 		reg |= (1 << CQSPI_REG_RD_INSTR_MODE_EN_LSB);
-- 
2.27.0