Since commit c4dd1ba355aae2bc3d1213da6c66c53e3c31e028
("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: [email protected] Cc: Patrice Chotard <[email protected]> Cc: Amelie Delaunay <[email protected]> Cc: Lee Jones <[email protected]> Fixes: c4dd1ba355aa ("mfd: stmpe: Add reset support for all STMPE variant") Signed-off-by: Linus Walleij <[email protected]> --- drivers/mfd/stmpe.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/mfd/stmpe.c b/drivers/mfd/stmpe.c index cfdae8a3d779..b0c7bcdaf5df 100644 --- a/drivers/mfd/stmpe.c +++ b/drivers/mfd/stmpe.c @@ -851,6 +851,8 @@ static int stmpe_reset(struct stmpe *stmpe) if (ret < 0) return ret; + msleep(10); + timeout = jiffies + msecs_to_jiffies(100); while (time_before(jiffies, timeout)) { ret = __stmpe_reg_read(stmpe, stmpe->regs[STMPE_IDX_SYS_CTRL]); -- 2.7.4
