lkml.org 
[lkml]   [2012]   [May]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 1/8] i2c: i2c-bfin-twi: Illegal i2c bus lock upon certain transfer scenarios.
    Date
    From: Michael Hennerich <michael.hennerich@analog.com>

    For transfer counts > 255 bytes i2c-bfin-twi sets the data
    transfer counter DCNT to 0xFF indicating unlimited transfers.
    It then uses a flag iface->manual_stop to manually issue the STOP
    condition, once the required amount of bytes are received.

    We found that on I2C receive operation issuing the STOP condition
    together with a FULL RCV FIFO (2bytes) will cause SDA and SCL be
    constantly driven low.

    Temporary workaround until further investigation:
    Discard the RCV FIFO before issuing the STOP condition.

    Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
    Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>

    git-svn-id: svn://localhost/svn/linux-kernel/trunk@9011 526b6c2d-f592-4532-a319-5dd88ccb003d
    ---
    drivers/i2c/busses/i2c-bfin-twi.c | 4 ++++
    1 files changed, 4 insertions(+), 0 deletions(-)

    diff --git a/drivers/i2c/busses/i2c-bfin-twi.c b/drivers/i2c/busses/i2c-bfin-twi.c
    index cdb59e5..e6dd3c9 100644
    --- a/drivers/i2c/busses/i2c-bfin-twi.c
    +++ b/drivers/i2c/busses/i2c-bfin-twi.c
    @@ -131,6 +131,10 @@ static void bfin_twi_handle_interrupt(struct bfin_twi_iface *iface,
    iface->transPtr++;
    iface->readNum--;
    } else if (iface->manual_stop) {
    + /* Avoid possible bus stall -
    + * Flush FIFO before issuing the STOP condition
    + */
    + read_RCV_DATA16(iface);
    write_MASTER_CTL(iface,
    read_MASTER_CTL(iface) | STOP);
    } else if (iface->cur_mode == TWI_I2C_MODE_REPEAT &&
    --
    1.7.0.4



    \
     
     \ /
      Last update: 2012-05-16 10:21    [W:0.027 / U:149.868 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site