diff options
| author | Yi Li <yi.li@analog.com> | 2009-04-06 19:00:44 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-04-07 08:31:06 -0700 |
| commit | 2cf3683472f043e6748c48228df6d8a35a47ecc2 (patch) | |
| tree | 6a7d950cffc88c9a71d314c58dafd0e3cf77a30c /drivers/spi/spi_bfin5xx.c | |
| parent | a963ea83b316b0a3ebf1c7118a6c36b5cd334bb6 (diff) | |
| download | lwn-2cf3683472f043e6748c48228df6d8a35a47ecc2.tar.gz lwn-2cf3683472f043e6748c48228df6d8a35a47ecc2.zip | |
Blackfin SPI Driver: fix bug - spi controller driver does not assert/deassert CS correctly
This bug can be observed when two SPI devices are sharing the spi bus: One
device is set as SPI CS 7, another one is using SPI CS 4.
In spi_bfin5xx.c: cs_active(), cs_deactive() are used to control SPI_FLG
register. From the debug bellow:
cs_active: flag: 0x7f91, chip->flag: 0x7f80, cs: 7
cs_active: flag: 0xef91, chip->flag: 0xef10, cs: 4
When device A (cs_7) activate CS 7, SPI_FLG is set as 0x7f91 (however,
SPI_FLG should be set as 0x7f80, or 0x6f91 if in broadcast mode).
Due to some HW bug (very possibly), if SPI_FLG is set as 0x7f91, SPISSEL7
is asserted, however SPISSEL4 will be asserted too (I can see this using
the scope). This is unreasonable according to HRM.
Signed-off-by: Yi Li <yi.li@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/spi/spi_bfin5xx.c')
| -rw-r--r-- | drivers/spi/spi_bfin5xx.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/drivers/spi/spi_bfin5xx.c b/drivers/spi/spi_bfin5xx.c index 317731a9cd6d..122292557bf3 100644 --- a/drivers/spi/spi_bfin5xx.c +++ b/drivers/spi/spi_bfin5xx.c @@ -189,6 +189,7 @@ static void cs_deactive(struct driver_data *drv_data, struct chip_data *chip) { u16 flag = read_FLAG(drv_data); + flag &= ~chip->flag; flag |= (chip->flag << 8); write_FLAG(drv_data, flag); @@ -1036,7 +1037,6 @@ static int setup(struct spi_device *spi) struct bfin5xx_spi_chip *chip_info = NULL; struct chip_data *chip; struct driver_data *drv_data = spi_master_get_devdata(spi->master); - u8 spi_flg; /* Abort device setup if requested features are not supported */ if (spi->mode & ~(SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST)) { @@ -1119,8 +1119,7 @@ static int setup(struct spi_device *spi) * SPI_BAUD, not the real baudrate */ chip->baud = hz_to_spi_baud(spi->max_speed_hz); - spi_flg = ~(1 << (spi->chip_select)); - chip->flag = ((u16) spi_flg << 8) | (1 << (spi->chip_select)); + chip->flag = 1 << (spi->chip_select); chip->chip_select_num = spi->chip_select; switch (chip->bits_per_word) { |