2021-01-14 15:42:08

by Alexandru Ardelean

Subject: [PATCH] spi: cadence: cache reference clock rate during probe

From: Michael Hennerich <[email protected]>

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 <[email protected]>
Signed-off-by: Alexandru Ardelean <[email protected]>
---
drivers/spi/spi-cadence.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-cadence.c b/drivers/spi/spi-cadence.c
index 70467b9d61ba..a3afd1b9ac56 100644
--- a/drivers/spi/spi-cadence.c
+++ b/drivers/spi/spi-cadence.c
@@ -115,6 +115,7 @@ 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;
@@ -250,7 +251,7 @@ static void cdns_spi_config_clock_freq(struct spi_device *spi,
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);

@@ -558,8 +559,9 @@ static int cdns_spi_probe(struct platform_device *pdev)
master->auto_runtime_pm = true;
master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;

+ 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);
--
2.17.1

2021-01-15 18:25:51

by Mark Brown

Subject: Re: [PATCH] spi: cadence: cache reference clock rate during probe

On Thu, 14 Jan 2021 17:42:17 +0200, Alexandru Ardelean wrote:
> The issue is that using SPI from a callback under the CCF lock will
> deadlock, since this code uses clk_get_rate().

Applied to

https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next

Thanks!

[1/1] spi: cadence: cache reference clock rate during probe
commit: 4d163ad79b155c71bf30366dc38f8d2502f78844

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark