• Linus Walleij's avatar
    mfd: stmpe: Fix RESET regression on STMPE2401 · 50e6cd2f
    Linus Walleij authored
    commit f4058420 upstream.
    
    Since commit c4dd1ba3
    ("mfd: stmpe: Add reset support for all STMPE variant")
    we're resetting the STMPE expanders before use.
    
    This caused a regression on the STMP2401 on the Nomadik
    NHK8815:
    
    stmpe-i2c 0-0043: stmpe2401 detected, chip id: 0x101
    nmk-i2c 101f8000.i2c0: write to slave 0x43 timed out
    nmk-i2c 101f8000.i2c0: no ack received after address transmission
    stmpe-i2c 0-0044: stmpe2401 detected, chip id: 0x101
    nmk-i2c 101f8000.i2c0: write to slave 0x44 timed out
    nmk-i2c 101f8000.i2c0: no ack received after address transmission
    
    It turns out that we start to poll for the reset bit to
    go low again too quickly: the STMPE2401 is not yet online and
    ready to be asked for the status of the RESET bit.
    
    By introducing a 10ms delay before starting to hammer
    the register for information, we get back to normal:
    
    stmpe-i2c 0-0043: stmpe2401 detected, chip id: 0x101
    stmpe-i2c 0-0044: stmpe2401 detected, chip id: 0x101
    
    Cc: Amelie Delaunay <amelie.delaunay@st.com>
    Fixes: c4dd1ba3 ("mfd: stmpe: Add reset support for all STMPE variant")
    Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
    Acked-by: default avatarPatrice Chotard <patrice.chotard@st.com>
    Signed-off-by: default avatarLee Jones <lee.jones@linaro.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    50e6cd2f
stmpe.c 32 KB