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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,
        Michael Hennerich <michael.hennerich@analog.com>,
        Alexandru Ardelean <alexandru.ardelean@analog.com>,
        Mark Brown <broonie@kernel.org>
Subject: [PATCH 4.19 22/22] spi: cadence: cache reference clock rate during probe
Date:   Fri, 22 Jan 2021 15:12:40 +0100
Message-Id: <20210122135732.786726542@linuxfoundation.org>
In-Reply-To: <20210122135731.921636245@linuxfoundation.org>
References: <20210122135731.921636245@linuxfoundation.org>
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From: Michael Hennerich <michael.hennerich@analog.com>

commit 4d163ad79b155c71bf30366dc38f8d2502f78844 upstream.

The issue is that using SPI from a callback under the CCF lock will
deadlock, since this code uses clk_get_rate().

Fixes: c474b38665463 ("spi: Add driver for Cadence SPI controller")
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20210114154217.51996-1-alexandru.ardelean@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/spi/spi-cadence.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/spi/spi-cadence.c
+++ b/drivers/spi/spi-cadence.c
@@ -119,6 +119,7 @@ struct cdns_spi {
 	void __iomem *regs;
 	struct clk *ref_clk;
 	struct clk *pclk;
+	unsigned int clk_rate;
 	u32 speed_hz;
 	const u8 *txbuf;
 	u8 *rxbuf;
@@ -258,7 +259,7 @@ static void cdns_spi_config_clock_freq(s
 	u32 ctrl_reg, baud_rate_val;
 	unsigned long frequency;
 
-	frequency = clk_get_rate(xspi->ref_clk);
+	frequency = xspi->clk_rate;
 
 	ctrl_reg = cdns_spi_read(xspi, CDNS_SPI_CR);
 
@@ -628,8 +629,9 @@ static int cdns_spi_probe(struct platfor
 	master->auto_runtime_pm = true;
 	master->mode_bits = SPI_CPOL | SPI_CPHA;
 
+	xspi->clk_rate = clk_get_rate(xspi->ref_clk);
 	/* Set to default valid value */
-	master->max_speed_hz = clk_get_rate(xspi->ref_clk) / 4;
+	master->max_speed_hz = xspi->clk_rate / 4;
 	xspi->speed_hz = master->max_speed_hz;
 
 	master->bits_per_word_mask = SPI_BPW_MASK(8);