Messages in this thread | | | Date | Wed, 2 Nov 2016 14:39:58 +0000 | From | Lee Jones <> | Subject | Re: [PATCH] mfd: stmpe: Fix RESET regression on STMPE2401 |
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On Tue, 01 Nov 2016, Linus Walleij wrote:
> 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(+)
Applied to -fixes.
> 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]);
-- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog
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