spi: cadence-quadspi: Abort read if dummy cycles required are too many

[ 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@ti.com>
Link: https://lore.kernel.org/r/20201222184425.7028-3-p.yadav@ti.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/mtd/spi-nor/cadence-quadspi.c b/drivers/mtd/spi-nor/cadence-quadspi.c
index ff4edf4bb23c5f853e33541eaa459503b5ce8c95..e58923d25f4a54d6810143daf57694a599ccc7f1 100644 (file)
--- a/drivers/mtd/spi-nor/cadence-quadspi.c
+++ b/drivers/mtd/spi-nor/cadence-quadspi.c
@@ -465,7 +465,7 @@ 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);