spi: omap2-mcspi: disable other channels CHCONF_FORCE in prepare_message
RFC PATCH 1/1 spi: omap2-mcspi: disable other channels CHCONF_FORCE in prepare_message
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.
--- 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
drivers/spi/spi-omap2-mcspi.c +28 -0
@@ -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;
Signature · 1 line
1.9.1
Quoted 32 lines · Neil Armstrong
Since the "Switch driver to use
transfer_one" change, thecs_changebehavior has changed and a channel chip select can still be asserted when changing channel from a previous last transfer in s message having thecs_changeattribute.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_messagecalled right before aspi_transfer_one_messagecall.This is also a bug fix found in the McSPI into a DM8168 SoC, hanging all the other channels transfers when a
CHCONF_FORCEis 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 withcs_changeafter "Switch driver to usetransfer_one" change'
http://permalink.gmane.org/gmane.linux.kernel/2056841drivers/spi/spi-omap2-mcspi.c +3
-0@@ -1217,6 +1217,33 @@ out:return status; } +static int omap2_mcspi_prepare_message (struct spi_master *master, +struct spi_message *msg) +{
drivers/spi/spi-omap2-mcspi.c out: · line 1232
Quoted 10 lines
drivers/spi/spi-omap2-mcspi.c +10
-0+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?
Quoted 28 lines
drivers/spi/spi-omap2-mcspi.c +15
-0+/* 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;Signature · 1 line
1.9.1
Mark Brown
maintainerQuoted 8 lines · Michael Welling
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_unusedfor the variable instead?drivers/spi/spi-omap2-mcspi.c out: · line 1234
Quoted 2 lines
drivers/spi/spi-omap2-mcspi.c +2
-0+/* 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.
Quoted 7 lines · Mark Brown
Quoted 5 lines · Michael Welling
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_unusedfor the variable instead?
Quoted 5 lines
Quoted 2 lines
drivers/spi/spi-omap2-mcspi.c out: · line 1234
Quoted 2 lines
drivers/spi/spi-omap2-mcspi.c +2
-0+/* 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?
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Mark Brown
maintainerQuoted 8 lines · Michael Welling
Quoted 6 lines · Mark Brown
Quoted 5 lines · Michael Welling
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_unusedfor the variable instead?
Quoted 7 lines
Quoted 5 lines
Quoted 2 lines
drivers/spi/spi-omap2-mcspi.c out: · line 1234
Quoted 2 lines
drivers/spi/spi-omap2-mcspi.c +2
-0+/* 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.