Messages in this thread Patch in this message |  | | From | Linus Walleij <> | Subject | [PATCH] mfd: stmpe: Fix RESET regression on STMPE2401 | Date | Tue, 1 Nov 2016 10:22:53 +0100 |
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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: stable@vger.kernel.org Cc: Patrice Chotard <patrice.chotard@st.com> Cc: Amelie Delaunay <amelie.delaunay@st.com> Cc: Lee Jones <lee.jones@linaro.org> Fixes: c4dd1ba355aa ("mfd: stmpe: Add reset support for all STMPE variant") Signed-off-by: Linus Walleij <linus.walleij@linaro.org> --- 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
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