| Message ID | 5616816C.9020904@baylibre.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Oct 08, 2015 at 04:45:00PM +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 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 <narmstrong@baylibre.com> > --- > 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 > + */ > + What is the point of doing this void cast below? Avoiding compiler warning perhaps? Perhaps you can __maybe_unused for the variable instead? > + /* 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 majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Oct 08, 2015 at 10:21:05AM -0500, Michael Welling wrote: > On Thu, Oct 08, 2015 at 04:45:00PM +0200, Neil Armstrong wrote: > What is the point of doing this void cast below? > Avoiding compiler warning perhaps? > Perhaps you can __maybe_unused for the variable instead? > > + /* Ignore message */ > > + (void)msg; You shouldn't need it at all, but yes if there is a good reason to mark something as unused the above annotation is better.
On Fri, Oct 09, 2015 at 12:38:10PM +0100, Mark Brown wrote: > On Thu, Oct 08, 2015 at 10:21:05AM -0500, Michael Welling wrote: > > On Thu, Oct 08, 2015 at 04:45:00PM +0200, Neil Armstrong wrote: > > > What is the point of doing this void cast below? > > Avoiding compiler warning perhaps? > > Perhaps you can __maybe_unused for the variable instead? > > > > + /* Ignore message */ > > > + (void)msg; > > You shouldn't need it at all, but yes if there is a good reason to mark > something as unused the above annotation is better. Which one? -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, Oct 09, 2015 at 09:24:51AM -0500, Michael Welling wrote: > On Fri, Oct 09, 2015 at 12:38:10PM +0100, Mark Brown wrote: > > On Thu, Oct 08, 2015 at 10:21:05AM -0500, Michael Welling wrote: > > > On Thu, Oct 08, 2015 at 04:45:00PM +0200, Neil Armstrong wrote: > > > What is the point of doing this void cast below? > > > Avoiding compiler warning perhaps? > > > Perhaps you can __maybe_unused for the variable instead? > > > > + /* Ignore message */ > > > > + (void)msg; > > You shouldn't need it at all, but yes if there is a good reason to mark > > something as unused the above annotation is better. > Which one? __maybe_unused.
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;
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 <narmstrong@baylibre.com> --- 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