| Message ID | 20221103080043.3033414-1-sean@geanix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | spi: stm32: fix stm32_spi_prepare_mbr() that halves spi clk for every run | expand |
On Thu, 3 Nov 2022 09:00:42 +0100, Sean Nyekjaer wrote: > When this driver is used with a driver that uses preallocated spi_transfer > structs. The speed_hz is halved by every run. This results in: > > spi_stm32 44004000.spi: SPI transfer setup failed > ads7846 spi0.0: SPI transfer failed: -22 > > Example when running with DIV_ROUND_UP(): > - First run; speed_hz = 1000000, spi->clk_rate 125000000 > div 125 -> mbrdiv = 7, cur_speed = 976562 > - Second run; speed_hz = 976562 > div 128,00007 (roundup to 129) -> mbrdiv = 8, cur_speed = 488281 > - Third run; speed_hz = 488281 > div 256,000131072067109 (roundup to 257) and then -EINVAL is returned. > > [...] Applied to https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next Thanks! [1/1] spi: stm32: fix stm32_spi_prepare_mbr() that halves spi clk for every run commit: 62aa1a344b0904549f6de7af958e8a1136fd5228 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
diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c index 6fe617b445a5..d6833361409d 100644 --- a/drivers/spi/spi-stm32.c +++ b/drivers/spi/spi-stm32.c @@ -434,7 +434,7 @@ static int stm32_spi_prepare_mbr(struct stm32_spi *spi, u32 speed_hz, u32 div, mbrdiv; /* Ensure spi->clk_rate is even */ - div = DIV_ROUND_UP(spi->clk_rate & ~0x1, speed_hz); + div = DIV_ROUND_CLOSEST(spi->clk_rate & ~0x1, speed_hz); /* * SPI framework set xfer->speed_hz to master->max_speed_hz if
When this driver is used with a driver that uses preallocated spi_transfer structs. The speed_hz is halved by every run. This results in: spi_stm32 44004000.spi: SPI transfer setup failed ads7846 spi0.0: SPI transfer failed: -22 Example when running with DIV_ROUND_UP(): - First run; speed_hz = 1000000, spi->clk_rate 125000000 div 125 -> mbrdiv = 7, cur_speed = 976562 - Second run; speed_hz = 976562 div 128,00007 (roundup to 129) -> mbrdiv = 8, cur_speed = 488281 - Third run; speed_hz = 488281 div 256,000131072067109 (roundup to 257) and then -EINVAL is returned. Use DIV_ROUND_CLOSEST to allow to round down and allow us to keep the set speed. Signed-off-by: Sean Nyekjaer <sean@geanix.com> --- drivers/spi/spi-stm32.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)