• Matthias Schiffer's avatar
    i2c: mxs: ensure that DMA buffers are safe for DMA · 5190417b
    Matthias Schiffer authored
    We found that after commit 9c46929e
    ("ARM: implement THREAD_INFO_IN_TASK for uniprocessor systems"), the
    PCF85063 RTC driver stopped working on i.MX28 due to regmap_bulk_read()
    reading bogus data into a stack buffer. This is caused by the i2c-mxs
    driver using DMA transfers even for messages without the I2C_M_DMA_SAFE
    flag, and the aforementioned commit enabling vmapped stacks.
    
    As the MXS I2C controller requires DMA for reads of >4 bytes, DMA can't be
    disabled, so the issue is fixed by using i2c_get_dma_safe_msg_buf() to
    create a bounce buffer when needed.
    
    Fixes: 9c46929e ("ARM: implement THREAD_INFO_IN_TASK for uniprocessor systems")
    Signed-off-by: default avatarMatthias Schiffer <matthias.schiffer@ew.tq-group.com>
    Signed-off-by: default avatarWolfram Sang <wsa@kernel.org>
    5190417b
i2c-mxs.c 24.1 KB