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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Pratyush Yadav <p.yadav@ti.com>,
        Mark Brown <broonie@kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 110/247] spi: cadence-quadspi: Abort read if dummy cycles required are too many
Date:   Mon,  1 Mar 2021 17:12:10 +0100
Message-Id: <20210301161037.055643852@linuxfoundation.org>
In-Reply-To: <20210301161031.684018251@linuxfoundation.org>
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From: Pratyush Yadav <p.yadav@ti.com>

[ 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>
---
 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 04cedd3a2bf66..a92f531ad23a3 100644
--- a/drivers/mtd/spi-nor/cadence-quadspi.c
+++ b/drivers/mtd/spi-nor/cadence-quadspi.c
@@ -473,7 +473,7 @@ static int cqspi_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