linux-kernel - [PATCH 2/7] spi: cadence-quadspi: Abort read if dummy cycles required are too many

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Date:   Wed, 23 Dec 2020 00:14:20 +0530
From:   Pratyush Yadav <p.yadav@...com>
To:     Mark Brown <broonie@...nel.org>,
        Vignesh Raghavendra <vigneshr@...com>
CC:     Pratyush Yadav <p.yadav@...com>, <linux-spi@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH 2/7] spi: cadence-quadspi: Abort read if dummy cycles required are too many

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@...com>
---
 drivers/spi/spi-cadence-quadspi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
index ea3890c7d9ff..5efb1f929be0 100644
--- a/drivers/spi/spi-cadence-quadspi.c
+++ b/drivers/spi/spi-cadence-quadspi.c
@@ -461,7 +461,7 @@ static int cqspi_read_setup(struct cqspi_flash_pdata *f_pdata,
 	/* Setup dummy clock cycles */
 	dummy_clk = op->dummy.nbytes * 8;
 	if (dummy_clk > CQSPI_DUMMY_CLKS_MAX)
-		dummy_clk = CQSPI_DUMMY_CLKS_MAX;
+		return -EOPNOTSUPP;
 
 	if (dummy_clk)
 		reg |= (dummy_clk & CQSPI_REG_RD_INSTR_DUMMY_MASK)
-- 
2.28.0