Add filter bypass mode, which bypasses the low pass filter, high pass
filter and disables/unregister the clock rate notifier.
Currently a feature like bypassing the filter is not achievable
straightforward and not very deductive. The user has to look through the
code and call the set_lpf_3db_frequency and set_hpf_3db_frequency iio
attributes from the user interface using the corner cases (freq >
largest lpf supported by the part, respectively freq < smallest hpf
supported by the part). Moreover, in such case of bypassing the filter,
the input clock rate change might mess up things so we want to make sure
that it is disabled. Also, the feature will help emphasizing the filter
behavior, therefore adding it in the userspace will ease the
charcaterization of the filter's effects when active/disabled.
It was requested by users of the driver to ease the interaction with
different configuration modes of the device.
Signed-off-by: Antoniu Miclaus <[email protected]>
---
changes in v2:
- improve code readability when setting the filter modes
- add more explanations regarding the necessity of this feature in the commit
body.
drivers/iio/filter/admv8818.c | 65 ++++++++++++++++++++++++++++++-----
1 file changed, 56 insertions(+), 9 deletions(-)
diff --git a/drivers/iio/filter/admv8818.c b/drivers/iio/filter/admv8818.c
index fe8d46cb7f1d..848baa6e3bbf 100644
--- a/drivers/iio/filter/admv8818.c
+++ b/drivers/iio/filter/admv8818.c
@@ -78,6 +78,7 @@ enum {
enum {
ADMV8818_AUTO_MODE,
ADMV8818_MANUAL_MODE,
+ ADMV8818_BYPASS_MODE,
};
struct admv8818_state {
@@ -114,7 +115,8 @@ static const struct regmap_config admv8818_regmap_config = {
static const char * const admv8818_modes[] = {
[0] = "auto",
- [1] = "manual"
+ [1] = "manual",
+ [2] = "bypass"
};
static int __admv8818_hpf_select(struct admv8818_state *st, u64 freq)
@@ -394,6 +396,36 @@ static int admv8818_reg_access(struct iio_dev *indio_dev,
return regmap_write(st->regmap, reg, write_val);
}
+static int admv8818_filter_bypass(struct admv8818_state *st)
+{
+ int ret;
+
+ mutex_lock(&st->lock);
+
+ ret = regmap_update_bits(st->regmap, ADMV8818_REG_WR0_SW,
+ ADMV8818_SW_IN_SET_WR0_MSK |
+ ADMV8818_SW_IN_WR0_MSK |
+ ADMV8818_SW_OUT_SET_WR0_MSK |
+ ADMV8818_SW_OUT_WR0_MSK,
+ FIELD_PREP(ADMV8818_SW_IN_SET_WR0_MSK, 1) |
+ FIELD_PREP(ADMV8818_SW_IN_WR0_MSK, 0) |
+ FIELD_PREP(ADMV8818_SW_OUT_SET_WR0_MSK, 1) |
+ FIELD_PREP(ADMV8818_SW_OUT_WR0_MSK, 0));
+ if (ret)
+ goto exit;
+
+ ret = regmap_update_bits(st->regmap, ADMV8818_REG_WR0_FILTER,
+ ADMV8818_HPF_WR0_MSK |
+ ADMV8818_LPF_WR0_MSK,
+ FIELD_PREP(ADMV8818_HPF_WR0_MSK, 0) |
+ FIELD_PREP(ADMV8818_LPF_WR0_MSK, 0));
+
+exit:
+ mutex_unlock(&st->lock);
+
+ return ret;
+}
+
static int admv8818_get_mode(struct iio_dev *indio_dev,
const struct iio_chan_spec *chan)
{
@@ -411,14 +443,22 @@ static int admv8818_set_mode(struct iio_dev *indio_dev,
if (!st->clkin) {
if (mode == ADMV8818_MANUAL_MODE)
- return 0;
+ goto set_mode;
+
+ if (mode == ADMV8818_BYPASS_MODE) {
+ ret = admv8818_filter_bypass(st);
+ if (ret)
+ return ret;
+
+ goto set_mode;
+ }
return -EINVAL;
}
switch (mode) {
case ADMV8818_AUTO_MODE:
- if (!st->filter_mode)
+ if (st->filter_mode == ADMV8818_AUTO_MODE)
return 0;
ret = clk_prepare_enable(st->clkin);
@@ -434,20 +474,27 @@ static int admv8818_set_mode(struct iio_dev *indio_dev,
break;
case ADMV8818_MANUAL_MODE:
- if (st->filter_mode)
- return 0;
+ case ADMV8818_BYPASS_MODE:
+ if (st->filter_mode == ADMV8818_AUTO_MODE) {
+ clk_disable_unprepare(st->clkin);
- clk_disable_unprepare(st->clkin);
+ ret = clk_notifier_unregister(st->clkin, &st->nb);
+ if (ret)
+ return ret;
+ }
- ret = clk_notifier_unregister(st->clkin, &st->nb);
- if (ret)
- return ret;
+ if (mode == ADMV8818_BYPASS_MODE) {
+ ret = admv8818_filter_bypass(st);
+ if (ret)
+ return ret;
+ }
break;
default:
return -EINVAL;
}
+set_mode:
st->filter_mode = mode;
return ret;
--
2.41.0
Add documentation for the use of the bypass filter mode.
Signed-off-by: Antoniu Miclaus <[email protected]>
---
Documentation/ABI/testing/sysfs-bus-iio-filter-admv8818 | 2 ++
1 file changed, 2 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-bus-iio-filter-admv8818 b/Documentation/ABI/testing/sysfs-bus-iio-filter-admv8818
index f6c035752639..31dbb390573f 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio-filter-admv8818
+++ b/Documentation/ABI/testing/sysfs-bus-iio-filter-admv8818
@@ -7,6 +7,8 @@ Description:
- auto -> Adjust bandpass filter to track changes in input clock rate.
- manual -> disable/unregister the clock rate notifier / input clock tracking.
+ - bypass -> bypass low pass filter, high pass filter and disable/unregister
+ the clock rate notifier
What: /sys/bus/iio/devices/iio:deviceX/filter_mode
KernelVersion:
--
2.41.0
On Mon, 31 Jul 2023 11:49:26 +0300
Antoniu Miclaus <[email protected]> wrote:
> Add filter bypass mode, which bypasses the low pass filter, high pass
> filter and disables/unregister the clock rate notifier.
>
> Currently a feature like bypassing the filter is not achievable
> straightforward and not very deductive. The user has to look through the
> code and call the set_lpf_3db_frequency and set_hpf_3db_frequency iio
> attributes from the user interface using the corner cases (freq >
> largest lpf supported by the part, respectively freq < smallest hpf
> supported by the part). Moreover, in such case of bypassing the filter,
> the input clock rate change might mess up things so we want to make sure
> that it is disabled. Also, the feature will help emphasizing the filter
> behavior, therefore adding it in the userspace will ease the
> charcaterization of the filter's effects when active/disabled.
Reasoning is well laid out. Thanks! It's an unusual feature, but meh
it's also hidden in existing custom ABI so unlikely to cause any
problems.
>
> It was requested by users of the driver to ease the interaction with
> different configuration modes of the device.
>
> Signed-off-by: Antoniu Miclaus <[email protected]>
Applied to the togreg branch of iio.git and pushed out as testing for 0-day
to take a look at it and see if we missed anything.
> ---
> changes in v2:
> - improve code readability when setting the filter modes
> - add more explanations regarding the necessity of this feature in the commit
> body.
> drivers/iio/filter/admv8818.c | 65 ++++++++++++++++++++++++++++++-----
> 1 file changed, 56 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/iio/filter/admv8818.c b/drivers/iio/filter/admv8818.c
> index fe8d46cb7f1d..848baa6e3bbf 100644
> --- a/drivers/iio/filter/admv8818.c
> +++ b/drivers/iio/filter/admv8818.c
> @@ -78,6 +78,7 @@ enum {
> enum {
> ADMV8818_AUTO_MODE,
> ADMV8818_MANUAL_MODE,
> + ADMV8818_BYPASS_MODE,
> };
>
> struct admv8818_state {
> @@ -114,7 +115,8 @@ static const struct regmap_config admv8818_regmap_config = {
>
> static const char * const admv8818_modes[] = {
> [0] = "auto",
> - [1] = "manual"
> + [1] = "manual",
> + [2] = "bypass"
> };
>
> static int __admv8818_hpf_select(struct admv8818_state *st, u64 freq)
> @@ -394,6 +396,36 @@ static int admv8818_reg_access(struct iio_dev *indio_dev,
> return regmap_write(st->regmap, reg, write_val);
> }
>
> +static int admv8818_filter_bypass(struct admv8818_state *st)
> +{
> + int ret;
> +
> + mutex_lock(&st->lock);
> +
> + ret = regmap_update_bits(st->regmap, ADMV8818_REG_WR0_SW,
> + ADMV8818_SW_IN_SET_WR0_MSK |
> + ADMV8818_SW_IN_WR0_MSK |
> + ADMV8818_SW_OUT_SET_WR0_MSK |
> + ADMV8818_SW_OUT_WR0_MSK,
> + FIELD_PREP(ADMV8818_SW_IN_SET_WR0_MSK, 1) |
> + FIELD_PREP(ADMV8818_SW_IN_WR0_MSK, 0) |
> + FIELD_PREP(ADMV8818_SW_OUT_SET_WR0_MSK, 1) |
> + FIELD_PREP(ADMV8818_SW_OUT_WR0_MSK, 0));
> + if (ret)
> + goto exit;
> +
> + ret = regmap_update_bits(st->regmap, ADMV8818_REG_WR0_FILTER,
> + ADMV8818_HPF_WR0_MSK |
> + ADMV8818_LPF_WR0_MSK,
> + FIELD_PREP(ADMV8818_HPF_WR0_MSK, 0) |
> + FIELD_PREP(ADMV8818_LPF_WR0_MSK, 0));
> +
> +exit:
> + mutex_unlock(&st->lock);
> +
> + return ret;
> +}
> +
> static int admv8818_get_mode(struct iio_dev *indio_dev,
> const struct iio_chan_spec *chan)
> {
> @@ -411,14 +443,22 @@ static int admv8818_set_mode(struct iio_dev *indio_dev,
>
> if (!st->clkin) {
> if (mode == ADMV8818_MANUAL_MODE)
> - return 0;
> + goto set_mode;
> +
> + if (mode == ADMV8818_BYPASS_MODE) {
> + ret = admv8818_filter_bypass(st);
> + if (ret)
> + return ret;
> +
> + goto set_mode;
> + }
>
> return -EINVAL;
> }
>
> switch (mode) {
> case ADMV8818_AUTO_MODE:
> - if (!st->filter_mode)
> + if (st->filter_mode == ADMV8818_AUTO_MODE)
> return 0;
>
> ret = clk_prepare_enable(st->clkin);
> @@ -434,20 +474,27 @@ static int admv8818_set_mode(struct iio_dev *indio_dev,
>
> break;
> case ADMV8818_MANUAL_MODE:
> - if (st->filter_mode)
> - return 0;
> + case ADMV8818_BYPASS_MODE:
> + if (st->filter_mode == ADMV8818_AUTO_MODE) {
> + clk_disable_unprepare(st->clkin);
>
> - clk_disable_unprepare(st->clkin);
> + ret = clk_notifier_unregister(st->clkin, &st->nb);
> + if (ret)
> + return ret;
> + }
>
> - ret = clk_notifier_unregister(st->clkin, &st->nb);
> - if (ret)
> - return ret;
> + if (mode == ADMV8818_BYPASS_MODE) {
> + ret = admv8818_filter_bypass(st);
> + if (ret)
> + return ret;
> + }
>
> break;
> default:
> return -EINVAL;
> }
>
> +set_mode:
> st->filter_mode = mode;
>
> return ret;