From: Gergely Imreh <imrehg@gmail.com> To: Jonathan Cameron <jic23@kernel.org> Cc: michal.simek@xilinx.com, linux-iio@vger.kernel.org, Linux ARM Kernel <linux-arm-kernel@lists.infradead.org>, linux-kernel@vger.kernel.org, ola@adapteva.com, Lars-Peter Clausen <lars@metafoo.de> Subject: Re: [PATCH 1/1] iio:adc: XADC: Set offset explicitly to zero on voltage channels Date: Sun, 14 Jun 2015 11:15:19 +0800 [thread overview] Message-ID: <CAJ3iQcoKPi7vCO5c==DcwwNY6LEKJ+xPueELDC85XPVus0qf0A@mail.gmail.com> (raw) In-Reply-To: <557C76D2.7030306@kernel.org> On 14 June 2015 at 02:30, Jonathan Cameron <jic23@kernel.org> wrote: > On 11/06/15 09:22, Gergely Imreh wrote: >> The Xilinx XADC driver has both a temperature channel and 8 voltage >> channels. The voltage channels have no offset, but actually were still >> set the same offset as the temperature channel. This did not cause >> problems in /sys/bus/iio/ but can cause problems with other drivers >> using iio data. For example iio-hwmon did return wrong voltage values >> because of the offset. >> >> Change tested with the Parallella board. >> >> Signed-off-by: Gergely Imreh <imrehg@gmail.com> > Well spotted on the bug, but I think we are better off fixing this at the > true source of the problem which is in drivers/iio/inkern.c > iio_convert_raw_to_processed_unlocked which does a call to > iio_channel_read(chan, &offset, NULL, IIO_CHAN_INFO_OFFSET) then uses > the error return to check if the offset parameter is available. It should > be checking that before making this call with a call to iio_channel_has_info. > > I don't suppose you could prepare a patch fixing that as you found the problem? I'll check it out, and send an updated patch! Thanks for the pointers to the core of the issue. > > If not I can fix it up sometime if no one else beats me to it. > > Thanks > > Jonathan >> --- >> drivers/iio/adc/xilinx-xadc-core.c | 14 +++++++++++--- >> 1 file changed, 11 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/iio/adc/xilinx-xadc-core.c b/drivers/iio/adc/xilinx-xadc-core.c >> index ab52be2..36efab7 100644 >> --- a/drivers/iio/adc/xilinx-xadc-core.c >> +++ b/drivers/iio/adc/xilinx-xadc-core.c >> @@ -877,9 +877,17 @@ static int xadc_read_raw(struct iio_dev *indio_dev, >> return -EINVAL; >> } >> case IIO_CHAN_INFO_OFFSET: >> - /* Only the temperature channel has an offset */ >> - *val = -((273150 << 12) / 503975); >> - return IIO_VAL_INT; >> + switch (chan->type) { >> + case IIO_VOLTAGE: >> + *val = 0; >> + return IIO_VAL_INT; >> + case IIO_TEMP: >> + /* Only the temperature channel has an offset */ >> + *val = -((273150 << 12) / 503975); >> + return IIO_VAL_INT; >> + default: >> + return -EINVAL; >> + } >> case IIO_CHAN_INFO_SAMP_FREQ: >> ret = xadc_read_adc_reg(xadc, XADC_REG_CONF2, &val16); >> if (ret) >> >
WARNING: multiple messages have this Message-ID (diff)
From: imrehg@gmail.com (Gergely Imreh) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 1/1] iio:adc: XADC: Set offset explicitly to zero on voltage channels Date: Sun, 14 Jun 2015 11:15:19 +0800 [thread overview] Message-ID: <CAJ3iQcoKPi7vCO5c==DcwwNY6LEKJ+xPueELDC85XPVus0qf0A@mail.gmail.com> (raw) In-Reply-To: <557C76D2.7030306@kernel.org> On 14 June 2015 at 02:30, Jonathan Cameron <jic23@kernel.org> wrote: > On 11/06/15 09:22, Gergely Imreh wrote: >> The Xilinx XADC driver has both a temperature channel and 8 voltage >> channels. The voltage channels have no offset, but actually were still >> set the same offset as the temperature channel. This did not cause >> problems in /sys/bus/iio/ but can cause problems with other drivers >> using iio data. For example iio-hwmon did return wrong voltage values >> because of the offset. >> >> Change tested with the Parallella board. >> >> Signed-off-by: Gergely Imreh <imrehg@gmail.com> > Well spotted on the bug, but I think we are better off fixing this at the > true source of the problem which is in drivers/iio/inkern.c > iio_convert_raw_to_processed_unlocked which does a call to > iio_channel_read(chan, &offset, NULL, IIO_CHAN_INFO_OFFSET) then uses > the error return to check if the offset parameter is available. It should > be checking that before making this call with a call to iio_channel_has_info. > > I don't suppose you could prepare a patch fixing that as you found the problem? I'll check it out, and send an updated patch! Thanks for the pointers to the core of the issue. > > If not I can fix it up sometime if no one else beats me to it. > > Thanks > > Jonathan >> --- >> drivers/iio/adc/xilinx-xadc-core.c | 14 +++++++++++--- >> 1 file changed, 11 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/iio/adc/xilinx-xadc-core.c b/drivers/iio/adc/xilinx-xadc-core.c >> index ab52be2..36efab7 100644 >> --- a/drivers/iio/adc/xilinx-xadc-core.c >> +++ b/drivers/iio/adc/xilinx-xadc-core.c >> @@ -877,9 +877,17 @@ static int xadc_read_raw(struct iio_dev *indio_dev, >> return -EINVAL; >> } >> case IIO_CHAN_INFO_OFFSET: >> - /* Only the temperature channel has an offset */ >> - *val = -((273150 << 12) / 503975); >> - return IIO_VAL_INT; >> + switch (chan->type) { >> + case IIO_VOLTAGE: >> + *val = 0; >> + return IIO_VAL_INT; >> + case IIO_TEMP: >> + /* Only the temperature channel has an offset */ >> + *val = -((273150 << 12) / 503975); >> + return IIO_VAL_INT; >> + default: >> + return -EINVAL; >> + } >> case IIO_CHAN_INFO_SAMP_FREQ: >> ret = xadc_read_adc_reg(xadc, XADC_REG_CONF2, &val16); >> if (ret) >> >
next prev parent reply other threads:[~2015-06-14 3:15 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-06-11 8:22 [PATCH 1/1] iio:adc: XADC: Set offset explicitly to zero on voltage channels Gergely Imreh 2015-06-11 8:22 ` Gergely Imreh 2015-06-13 18:30 ` Jonathan Cameron 2015-06-13 18:30 ` Jonathan Cameron 2015-06-14 3:15 ` Gergely Imreh [this message] 2015-06-14 3:15 ` Gergely Imreh 2015-06-14 15:45 ` Lars-Peter Clausen 2015-06-14 15:45 ` Lars-Peter Clausen 2015-06-14 15:55 ` Jonathan Cameron 2015-06-14 15:55 ` Jonathan Cameron 2015-06-15 2:07 ` Gergely Imreh 2015-06-15 2:07 ` Gergely Imreh
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