On Fri, Oct 09, 2015 at 03:47:41PM +0200, Neil Armstrong wrote:
> Since the "Switch driver to use transfer_one" change, the cs_change
> behavior has changed and a channel chip select can still be
> asserted when changing channel from a previous last transfer in a
> message having the cs_change attribute.
>
> Since there is no sense having multiple chip select being asserted at the
> same time, disable all the remaining forced chip selects in a the
> prepare_message called right before a spi_transfer_one_message call.
> It ignores the current channel configuration in order to keep the
> possibility to leave the chip select asserted between messages.
>
> It fixes this bug on a DM8168 SoC ES2.1 Soc and an OMAP4 ES2.1 SoC.
> It was hanging all the other channels transfers when a CHCONF_FORCE
> is present on the wrong channel.
>
> Fixes: b28cb9414db9 ("spi: omap2-mcspi: Switch driver to use transfer_one")
> Signed-off-by: Neil Armstrong <narmstr...@baylibre.com>
> ---
> drivers/spi/spi-omap2-mcspi.c | 28 ++++++++++++++++++++++++++++
> 1 file changed, 28 insertions(+)
>
> Test code can be found on :
> http://pastebin.com/0SrqbGP7
>
> Before patch :
> # ./test_spi
> cs_change_command() start
> spidev1.3 ioctl success
> no_dma_command() start
> [ 59.790069] spidev spi1.1: TXS timed out
> spidev1.1 ioctl success
> cs_change_command() start
> [ 60.798736] spidev spi1.3: RXS timed out
> spidev1.3 ioctl success
> no_dma_command() start
> [ 61.802032] spidev spi1.1: TXS timed out
> spidev1.1 ioctl success
> cs_change_command() start
> [ 62.807525] spidev spi1.3: RXS timed out
> spidev1.3 ioctl success
> no_dma_command() start
> [ 63.812042] spidev spi1.1: TXS timed out
> spidev1.1 ioctl success
> ...
>
> After Patch :
> # ./test_spi
> cs_change_command() start
> spidev1.3 ioctl success
> no_dma_command() start
> spidev1.1 ioctl success
> cs_change_command() start
> spidev1.3 ioctl success
> no_dma_command() start
> spidev1.1 ioctl success
> cs_change_command() start
> spidev1.3 ioctl success
> ...
>
> v2: uses msg to leave asserted chip select for the current channel
>
> This is a patch RFC following the bug report :
> 'McSPI hangs with cs_change after "Switch driver to use transfer_one" change'
> http://permalink.gmane.org/gmane.linux.kernel/2056841
>
> diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
> index 3d09e0b..1f8903d 100644
> --- a/drivers/spi/spi-omap2-mcspi.c
> +++ b/drivers/spi/spi-omap2-mcspi.c
> @@ -1217,6 +1217,33 @@ out:
> return status;
> }
>
> +static int omap2_mcspi_prepare_message(struct spi_master *master,
> + struct spi_message *msg)
> +{
> + struct omap2_mcspi *mcspi = spi_master_get_devdata(master);
> + struct omap2_mcspi_regs *ctx = &mcspi->ctx;
> + struct omap2_mcspi_cs *cs;
> +
Do we need the pm_runtime_get_sync code here?
See previous commit.
> + /* Only a single channel can have the FORCE bit enabled
> + * in its chconf0 register.
> + * Scan all channels and disable them except the current one.
> + * A FORCE can remain from a last transfer having cs_change enabled
> + */
> + list_for_each_entry(cs, &ctx->cs, node) {
> + if (msg->spi->controller_state == cs)
> + continue;
> +
> + if ((cs->chconf0 & OMAP2_MCSPI_CHCONF_FORCE)) {
> + cs->chconf0 &= ~OMAP2_MCSPI_CHCONF_FORCE;
> + writel_relaxed(cs->chconf0,
> + cs->base + OMAP2_MCSPI_CHCONF0);
> + readl_relaxed(cs->base + OMAP2_MCSPI_CHCONF0);
> + }
> + }
> +
> + return 0;
> +}
> +
> static int omap2_mcspi_transfer_one(struct spi_master *master,
> struct spi_device *spi, struct spi_transfer *t)
> {
> @@ -1344,6 +1371,7 @@ static int omap2_mcspi_probe(struct platform_device
> *pdev)
> master->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 32);
> master->setup = omap2_mcspi_setup;
> master->auto_runtime_pm = true;
> + master->prepare_message = omap2_mcspi_prepare_message;
> master->transfer_one = omap2_mcspi_transfer_one;
> master->set_cs = omap2_mcspi_set_cs;
> master->cleanup = omap2_mcspi_cleanup;
> --
> 1.9.1
>
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