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 s 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 forces chip selects in a the prepare_message called right before a spi_transfer_one_message call. This is also a bug fix found in the McSPI into a DM8168 SoC, hanging all the other channels transfers when a CHCONF_FORCE is present. Signed-off-by: Neil Armstrong <[email protected]> --- drivers/spi/spi-omap2-mcspi.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) 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..db1b655 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; + + /* Only a single channel can have the FORCE bit enabled + * in its chconf0 register. + * Scan all channels and disable them. + * A FORCE can remain from a last transfer having cs_change enabled + */ + + /* Ignore message */ + (void)msg; + + list_for_each_entry(cs, &ctx->cs, node) { + if ((cs->chconf0 & OMAP2_MCSPI_CHCONF_FORCE)) { + cs->chconf0 &= ~OMAP2_MCSPI_CHCONF_FORCE; + writel_relaxed(cs->chconf0, + 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 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
