* [PATCH v2] iio: afe: iio-rescale: Support processed channels
@ 2021-05-09 22:59 Linus Walleij
2021-05-10 8:10 ` Peter Rosin
0 siblings, 1 reply; 2+ messages in thread
From: Linus Walleij @ 2021-05-09 22:59 UTC (permalink / raw)
To: Jonathan Cameron, linux-iio
Cc: Hartmut Knaack, Lars-Peter Clausen, Peter Meerwald-Stadler,
Linus Walleij, Peter Rosin
It happens that an ADC will only provide raw or processed
voltage conversion channels. (adc/ab8500-gpadc.c).
On the Samsung GT-I9070 this is used for a light sensor
and current sense amplifier so we need to think of something.
The idea is to allow processed channels and scale them
with 1/1 and then the rescaler can modify the result
on top.
Link: https://lore.kernel.org/linux-iio/20201101232211.1194304-1-linus.walleij@linaro.org/
Cc: Peter Rosin <peda@axentia.se>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
ChangeLog v1->v2:
- Deny calls to .read_avail() for processed channels, and
insert a comment.
- Move an assignment of IIO_VAL_FRACTIONAL down to the end
of the block for better readability.
---
drivers/iio/afe/iio-rescale.c | 39 +++++++++++++++++++++++++++++++----
1 file changed, 35 insertions(+), 4 deletions(-)
diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
index e42ea2b1707d..ddbb760ae8df 100644
--- a/drivers/iio/afe/iio-rescale.c
+++ b/drivers/iio/afe/iio-rescale.c
@@ -29,6 +29,7 @@ struct rescale {
struct iio_channel *source;
struct iio_chan_spec chan;
struct iio_chan_spec_ext_info *ext_info;
+ bool chan_processed;
s32 numerator;
s32 denominator;
};
@@ -43,10 +44,27 @@ static int rescale_read_raw(struct iio_dev *indio_dev,
switch (mask) {
case IIO_CHAN_INFO_RAW:
- return iio_read_channel_raw(rescale->source, val);
+ if (rescale->chan_processed)
+ /*
+ * When only processed channels are supported, we
+ * read the processed data and scale it by 1/1
+ * augmented with whatever the rescaler has calculated.
+ */
+ return iio_read_channel_processed(rescale->source, val);
+ else
+ return iio_read_channel_raw(rescale->source, val);
case IIO_CHAN_INFO_SCALE:
- ret = iio_read_channel_scale(rescale->source, val, val2);
+ if (rescale->chan_processed) {
+ /*
+ * Processed channels are scaled 1-to-1
+ */
+ *val = 1;
+ *val2 = 1;
+ ret = IIO_VAL_FRACTIONAL;
+ } else {
+ ret = iio_read_channel_scale(rescale->source, val, val2);
+ }
switch (ret) {
case IIO_VAL_FRACTIONAL:
*val *= rescale->numerator;
@@ -82,6 +100,14 @@ static int rescale_read_avail(struct iio_dev *indio_dev,
switch (mask) {
case IIO_CHAN_INFO_RAW:
+ /*
+ * Using .read_avail() is fringe to begin with and makes
+ * no sense whatsoever for processed channels, so if called
+ * on a processed channel, we just error out here.
+ */
+ if (rescale->chan_processed)
+ return -EINVAL;
+
*type = IIO_VAL_INT;
return iio_read_avail_channel_raw(rescale->source,
vals, length);
@@ -132,8 +158,13 @@ static int rescale_configure_channel(struct device *dev,
if (!iio_channel_has_info(schan, IIO_CHAN_INFO_RAW) ||
!iio_channel_has_info(schan, IIO_CHAN_INFO_SCALE)) {
- dev_err(dev, "source channel does not support raw/scale\n");
- return -EINVAL;
+ if (iio_channel_has_info(schan, IIO_CHAN_INFO_PROCESSED)) {
+ dev_info(dev, "using processed channel\n");
+ rescale->chan_processed = true;
+ } else {
+ dev_err(dev, "source channel does not support raw+scale or processed data\n");
+ return -EINVAL;
+ }
}
chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
--
2.30.2
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] iio: afe: iio-rescale: Support processed channels
2021-05-09 22:59 [PATCH v2] iio: afe: iio-rescale: Support processed channels Linus Walleij
@ 2021-05-10 8:10 ` Peter Rosin
0 siblings, 0 replies; 2+ messages in thread
From: Peter Rosin @ 2021-05-10 8:10 UTC (permalink / raw)
To: Linus Walleij, Jonathan Cameron, linux-iio
Cc: Hartmut Knaack, Lars-Peter Clausen, Peter Meerwald-Stadler
Hi!
Thanks for the update!
On 2021-05-10 00:59, Linus Walleij wrote:
> It happens that an ADC will only provide raw or processed
> voltage conversion channels. (adc/ab8500-gpadc.c).
> On the Samsung GT-I9070 this is used for a light sensor
> and current sense amplifier so we need to think of something.
>
> The idea is to allow processed channels and scale them
> with 1/1 and then the rescaler can modify the result
> on top.
>
> Link: https://lore.kernel.org/linux-iio/20201101232211.1194304-1-linus.walleij@linaro.org/
> Cc: Peter Rosin <peda@axentia.se>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
> ChangeLog v1->v2:
> - Deny calls to .read_avail() for processed channels, and
> insert a comment.
> - Move an assignment of IIO_VAL_FRACTIONAL down to the end
> of the block for better readability.
> ---
> drivers/iio/afe/iio-rescale.c | 39 +++++++++++++++++++++++++++++++----
> 1 file changed, 35 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
> index e42ea2b1707d..ddbb760ae8df 100644
> --- a/drivers/iio/afe/iio-rescale.c
> +++ b/drivers/iio/afe/iio-rescale.c
> @@ -29,6 +29,7 @@ struct rescale {
> struct iio_channel *source;
> struct iio_chan_spec chan;
> struct iio_chan_spec_ext_info *ext_info;
> + bool chan_processed;
> s32 numerator;
> s32 denominator;
> };
> @@ -43,10 +44,27 @@ static int rescale_read_raw(struct iio_dev *indio_dev,
>
> switch (mask) {
> case IIO_CHAN_INFO_RAW:
> - return iio_read_channel_raw(rescale->source, val);
> + if (rescale->chan_processed)
> + /*
> + * When only processed channels are supported, we
> + * read the processed data and scale it by 1/1
> + * augmented with whatever the rescaler has calculated.
> + */
> + return iio_read_channel_processed(rescale->source, val);
> + else
> + return iio_read_channel_raw(rescale->source, val);
>
> case IIO_CHAN_INFO_SCALE:
> - ret = iio_read_channel_scale(rescale->source, val, val2);
> + if (rescale->chan_processed) {
> + /*
> + * Processed channels are scaled 1-to-1
> + */
> + *val = 1;
> + *val2 = 1;
> + ret = IIO_VAL_FRACTIONAL;
> + } else {
> + ret = iio_read_channel_scale(rescale->source, val, val2);
> + }
> switch (ret) {
> case IIO_VAL_FRACTIONAL:
> *val *= rescale->numerator;
> @@ -82,6 +100,14 @@ static int rescale_read_avail(struct iio_dev *indio_dev,
>
> switch (mask) {
> case IIO_CHAN_INFO_RAW:
> + /*
> + * Using .read_avail() is fringe to begin with and makes
> + * no sense whatsoever for processed channels, so if called
> + * on a processed channel, we just error out here.
> + */
> + if (rescale->chan_processed)
> + return -EINVAL;
> +
I believe this is not the correct place to block requests for .read_avail.
It's too late; the driver should not first promise that it is possible to
call .read_avail just to later return -EINVAL.
It's better to just avoid adding the IIO_CHAN_INFO_RAW bit to
chan->info_mask_separate_available in the rescale_configure_channel
function. See some suggested -++ below at the end...
> *type = IIO_VAL_INT;
> return iio_read_avail_channel_raw(rescale->source,
> vals, length);
> @@ -132,8 +158,13 @@ static int rescale_configure_channel(struct device *dev,
>
> if (!iio_channel_has_info(schan, IIO_CHAN_INFO_RAW) ||
> !iio_channel_has_info(schan, IIO_CHAN_INFO_SCALE)) {
> - dev_err(dev, "source channel does not support raw/scale\n");
> - return -EINVAL;
> + if (iio_channel_has_info(schan, IIO_CHAN_INFO_PROCESSED)) {
> + dev_info(dev, "using processed channel\n");
> + rescale->chan_processed = true;
> + } else {
> + dev_err(dev, "source channel does not support raw+scale or processed data\n");
> + return -EINVAL;
> + }
> }
I'd also rather have this logic reversed/flattened:
if (iio_channel_has_info(schan, IIO_CHAN_INFO_RAW) &&
iio_channel_has_info(schan, IIO_CHAN_INFO_SCALE)) {
dev_info(dev, "using raw+scale source channel\n");
} else if (iio_channel_has_info(schan, IIO_CHAN_INFO_PROCESSED)) {
dev_info(dev, "using processed source channel\n");
rescale->chan_processed = true;
} else {
dev_err(dev, "source channel is not supported\n");
return -EINVAL;
}
>
> chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
BIT(IIO_CHAN_INFO_SCALE);
- if (iio_channel_has_available(schan, IIO_CHAN_INFO_RAW))
+ if (iio_channel_has_available(schan, IIO_CHAN_INFO_RAW) &&
+ !rescale->chan_processed)
chan->info_mask_separate_available |= BIT(IIO_CHAN_INFO_RAW);
(disclaimer, all new code untested and written directly in the mail client)
CHeers,
Peter
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