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authorYi Li <yi.li@analog.com>2009-04-06 19:00:44 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-07 08:31:06 -0700
commit2cf3683472f043e6748c48228df6d8a35a47ecc2 (patch)
tree6a7d950cffc88c9a71d314c58dafd0e3cf77a30c /drivers/spi
parenta963ea83b316b0a3ebf1c7118a6c36b5cd334bb6 (diff)
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')
-rw-r--r--drivers/spi/spi_bfin5xx.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/drivers/spi/spi_bfin5xx.c b/drivers/spi/spi_bfin5xx.c
index 317731a9cd6..122292557bf 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) {