| Message ID | 20240624071745.17409-1-bastien.curutchet@bootlin.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 1762dc01fc78ef5f19693e9317eae7491c6c7e1b |
| Headers | show |
| Series | spi: davinci: Unset POWERDOWN bit when releasing resources | expand |
On Mon, 24 Jun 2024 09:17:45 +0200, Bastien Curutchet wrote: > On the OMAPL138, the SPI reference clock is provided by the Power and > Sleep Controller (PSC). The PSC's datasheet says that 'some peripherals > have special programming requirements and additional recommended steps > you must take before you can invoke the PSC module state transition'. I > didn't find more details in documentation but it appears that PSC needs > the SPI to clear the POWERDOWN bit before disabling the clock. Indeed, > when this bit is set, the PSC gets stuck in transitions from enable to > disable state. > > [...] Applied to https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next Thanks! [1/1] spi: davinci: Unset POWERDOWN bit when releasing resources commit: 1762dc01fc78ef5f19693e9317eae7491c6c7e1b 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-davinci.c b/drivers/spi/spi-davinci.c index be3998104bfb..f7e8b5efa50e 100644 --- a/drivers/spi/spi-davinci.c +++ b/drivers/spi/spi-davinci.c @@ -984,6 +984,9 @@ static int davinci_spi_probe(struct platform_device *pdev) return ret; free_dma: + /* This bit needs to be cleared to disable dpsi->clk */ + clear_io_bits(dspi->base + SPIGCR1, SPIGCR1_POWERDOWN_MASK); + if (dspi->dma_rx) { dma_release_channel(dspi->dma_rx); dma_release_channel(dspi->dma_tx); @@ -1013,6 +1016,9 @@ static void davinci_spi_remove(struct platform_device *pdev) spi_bitbang_stop(&dspi->bitbang); + /* This bit needs to be cleared to disable dpsi->clk */ + clear_io_bits(dspi->base + SPIGCR1, SPIGCR1_POWERDOWN_MASK); + if (dspi->dma_rx) { dma_release_channel(dspi->dma_rx); dma_release_channel(dspi->dma_tx);
On the OMAPL138, the SPI reference clock is provided by the Power and Sleep Controller (PSC). The PSC's datasheet says that 'some peripherals have special programming requirements and additional recommended steps you must take before you can invoke the PSC module state transition'. I didn't find more details in documentation but it appears that PSC needs the SPI to clear the POWERDOWN bit before disabling the clock. Indeed, when this bit is set, the PSC gets stuck in transitions from enable to disable state. Clear the POWERDOWN bit when releasing driver's resources Signed-off-by: Bastien Curutchet <bastien.curutchet@bootlin.com> --- Hi, I ran into this bug by enabling the 'cs-gpio' property. It causes the probe to fail at first with -EPROBE_DEFER because the gpio provider is not ready. So the clock gets disabled. In the clock controller's driver (drivers/clk/davinci/psc.c) the clock_disable() calls a regmap_read_poll_timeout() with an infinite timeout. This poll() polls a transition bit status that never goes down so we end stuck in the middle of the boot sequence. drivers/spi/spi-davinci.c | 6 ++++++ 1 file changed, 6 insertions(+)