4.8-stable review patch. If anyone has any objections, please let me know.
------------------ From: Linus Walleij <[email protected]> commit f40584200bc4af7aa4399635b9ac213c62a13ae7 upstream. 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: Amelie Delaunay <[email protected]> Fixes: c4dd1ba355aa ("mfd: stmpe: Add reset support for all STMPE variant") Signed-off-by: Linus Walleij <[email protected]> Acked-by: Patrice Chotard <[email protected]> Signed-off-by: Lee Jones <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/mfd/stmpe.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/mfd/stmpe.c +++ b/drivers/mfd/stmpe.c @@ -761,6 +761,8 @@ static int stmpe1801_reset(struct stmpe if (ret < 0) return ret; + msleep(10); + timeout = jiffies + msecs_to_jiffies(100); while (time_before(jiffies, timeout)) { ret = __stmpe_reg_read(stmpe, STMPE1801_REG_SYS_CTRL);
