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Subject[PATCH 10/10] SPI: spi_bitbang: clocking fixes
Date
From: David Brownell <david-b@pacbell.net>

This fixes two problems triggered by the MMC stack updating clocks:

- SPI masters driver should accept a max clock speed of zero; that's one
convention for marking idle devices. (Presumably that helps controllers
that don't autogate clocks to "off" when not in use.)

- There are more than 1000 nanoseconds per millisecond; setting the clock
down to 125 KHz now works properly.

Showing once again that Zero (http://en.wikipedia.org/wiki/Zero) is still
an inexhaustible number of bugs.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/spi/spi_bitbang.c | 24 ++++++++++++++----------
1 files changed, 14 insertions(+), 10 deletions(-)
1e316d7566b63767aa18902235c719e9e95465d0
diff --git a/drivers/spi/spi_bitbang.c b/drivers/spi/spi_bitbang.c
index 0f7f5c6..dd2f950 100644
--- a/drivers/spi/spi_bitbang.c
+++ b/drivers/spi/spi_bitbang.c
@@ -167,9 +167,11 @@ int spi_bitbang_setup_transfer(struct sp
/* nsecs = (clock period)/2 */
if (!hz)
hz = spi->max_speed_hz;
- cs->nsecs = (1000000000/2) / hz;
- if (cs->nsecs > MAX_UDELAY_MS * 1000)
- return -EINVAL;
+ if (hz) {
+ cs->nsecs = (1000000000/2) / hz;
+ if (cs->nsecs > (MAX_UDELAY_MS * 1000 * 1000))
+ return -EINVAL;
+ }

return 0;
}
@@ -184,9 +186,6 @@ int spi_bitbang_setup(struct spi_device
struct spi_bitbang *bitbang;
int retval;

- if (!spi->max_speed_hz)
- return -EINVAL;
-
bitbang = spi_master_get_devdata(spi->master);

/* REVISIT: some systems will want to support devices using lsb-first
@@ -216,7 +215,7 @@ int spi_bitbang_setup(struct spi_device
if (retval < 0)
return retval;

- dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u nsec\n",
+ dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u nsec/bit\n",
__FUNCTION__, spi->mode & (SPI_CPOL | SPI_CPHA),
spi->bits_per_word, 2 * cs->nsecs);

@@ -405,6 +404,7 @@ int spi_bitbang_transfer(struct spi_devi
{
struct spi_bitbang *bitbang;
unsigned long flags;
+ int status = 0;

m->actual_length = 0;
m->status = -EINPROGRESS;
@@ -414,11 +414,15 @@ int spi_bitbang_transfer(struct spi_devi
return -ESHUTDOWN;

spin_lock_irqsave(&bitbang->lock, flags);
- list_add_tail(&m->queue, &bitbang->queue);
- queue_work(bitbang->workqueue, &bitbang->work);
+ if (!spi->max_speed_hz)
+ status = -ENETDOWN;
+ else {
+ list_add_tail(&m->queue, &bitbang->queue);
+ queue_work(bitbang->workqueue, &bitbang->work);
+ }
spin_unlock_irqrestore(&bitbang->lock, flags);

- return 0;
+ return status;
}
EXPORT_SYMBOL_GPL(spi_bitbang_transfer);

--
1.3.2
-
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