Unverified Commit c45c1e82 authored by Alexandru Tachici's avatar Alexandru Tachici Committed by Mark Brown
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spi: spi-bcm2835: Fix deadlock 



The bcm2835_spi_transfer_one function can create a deadlock
if it is called while another thread already has the
CCF lock.

Signed-off-by: default avatarAlexandru Tachici <alexandru.tachici@analog.com>
Fixes: f8043872 ("spi: add driver for BCM2835")
Reviewed-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20210716210245.13240-2-alexandru.tachici@analog.com


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 56912da7

drivers/spi/spi-bcm2835.c

+7 −5
Original line number Diff line number Diff line
@@ -83,6 +83,7 @@ MODULE_PARM_DESC(polling_limit_us, 
 * struct bcm2835_spi - BCM2835 SPI controller

 * @regs: base address of register map

 * @clk: core clock, divided to calculate serial clock

 * @clk_hz: core clock cached speed

 * @irq: interrupt, signals TX FIFO empty or RX FIFO ¾ full

 * @tfr: SPI transfer currently processed

 * @ctlr: SPI controller reverse lookup
@@ -116,6 +117,7 @@ MODULE_PARM_DESC(polling_limit_us, 
struct bcm2835_spi {

	void __iomem *regs;

	struct clk *clk;

	unsigned long clk_hz;

	int irq;

	struct spi_transfer *tfr;

	struct spi_controller *ctlr;
@@ -1045,19 +1047,18 @@ static int bcm2835_spi_transfer_one(struct spi_controller *ctlr, 
{

	struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr);

	struct bcm2835_spidev *slv = spi_get_ctldata(spi);

	unsigned long spi_hz, clk_hz, cdiv;

	unsigned long spi_hz, cdiv;

	unsigned long hz_per_byte, byte_limit;

	u32 cs = slv->prepare_cs;



	/* set clock */

	spi_hz = tfr->speed_hz;

	clk_hz = clk_get_rate(bs->clk);



	if (spi_hz >= clk_hz / 2) {

	if (spi_hz >= bs->clk_hz / 2) {

		cdiv = 2; /* clk_hz/2 is the fastest we can go */

	} else if (spi_hz) {

		/* CDIV must be a multiple of two */

		cdiv = DIV_ROUND_UP(clk_hz, spi_hz);

		cdiv = DIV_ROUND_UP(bs->clk_hz, spi_hz);

		cdiv += (cdiv % 2);



		if (cdiv >= 65536)
@@ -1065,7 +1066,7 @@ static int bcm2835_spi_transfer_one(struct spi_controller *ctlr, 
	} else {

		cdiv = 0; /* 0 is the slowest we can go */

	}

	tfr->effective_speed_hz = cdiv ? (clk_hz / cdiv) : (clk_hz / 65536);

	tfr->effective_speed_hz = cdiv ? (bs->clk_hz / cdiv) : (bs->clk_hz / 65536);

	bcm2835_wr(bs, BCM2835_SPI_CLK, cdiv);



	/* handle all the 3-wire mode */
@@ -1354,6 +1355,7 @@ static int bcm2835_spi_probe(struct platform_device *pdev) 
		return bs->irq ? bs->irq : -ENODEV;



	clk_prepare_enable(bs->clk);

	bs->clk_hz = clk_get_rate(bs->clk);



	err = bcm2835_dma_init(ctlr, &pdev->dev, bs);

	if (err)