This reverts commit e7385de5291e347f5bc85985acdce3a3f5096667.
This change is bad, because it breaks all 12bit sensors and
breaks userspace such as iio_generic_buffer.
The commit computes the number of bytes to read out from the
hardware like this:
unsigned int bytes_to_read = channel->scan_type.realbits >> 3;
This works fine with 8 or 16 bit channels resulting in 1 or
2 bytes to read respectively.
But when using this with 12bit sensors such as the LIS3LV02
this fails since 12 >> 3 = 1 but we need to read 2 bytes!
Unless we do this, the DRDY signal does not go low and the
status loop just spins.
Further, it packs all bytes in the buffer to make it "dense".
Even if I try to fix the above by using DIV_ROUND_UP(),
it will result in erroneous data in the buffer for 12bit
sensors, since the macro ST_SENSORS_LSM_CHANNELS() used by
all sensors defines scan type shift, storagebits and realbits
such that the userspace like iio_generic_buffer will read
2 bytes, then shift it by 4. This will not work anymore after
this patch.
I do not understand the point of the original commit, I
suggest this be reverted for now.
Fixes: e7385de5291e ("iio:st_sensors: align on storagebits boundaries")
Cc: stable@xxxxxxxxxxxxxxx
Cc: Gregor Boirie <gregor.boirie@xxxxxxxxxx>
Cc: Giuseppe Barba <giuseppe.barba@xxxxxx>
Cc: Denis Ciocca <denis.ciocca@xxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
drivers/iio/common/st_sensors/st_sensors_buffer.c | 37 ++++++++++++-----------
drivers/iio/common/st_sensors/st_sensors_core.c | 2 +-
2 files changed, 20 insertions(+), 19 deletions(-)
diff --git a/drivers/iio/common/st_sensors/st_sensors_buffer.c b/drivers/iio/common/st_sensors/st_sensors_buffer.c
index fe7775bb3740..3c964a106afa 100644
--- a/drivers/iio/common/st_sensors/st_sensors_buffer.c
+++ b/drivers/iio/common/st_sensors/st_sensors_buffer.c
@@ -24,29 +24,30 @@
static int st_sensors_get_buffer_element(struct iio_dev *indio_dev, u8 *buf)
{
- int i;
+ int i, len;
+ int total = 0;
struct st_sensor_data *sdata = iio_priv(indio_dev);
unsigned int num_data_channels = sdata->num_data_channels;
- for_each_set_bit(i, indio_dev->active_scan_mask, num_data_channels) {
- const struct iio_chan_spec *channel = &indio_dev->channels[i];
- unsigned int bytes_to_read = channel->scan_type.realbits >> 3;
- unsigned int storage_bytes =
- channel->scan_type.storagebits >> 3;
-
- buf = PTR_ALIGN(buf, storage_bytes);
- if (sdata->tf->read_multiple_byte(&sdata->tb, sdata->dev,
- channel->address,
- bytes_to_read, buf,
- sdata->multiread_bit) <
- bytes_to_read)
- return -EIO;
-
- /* Advance the buffer pointer */
- buf += storage_bytes;
+ for (i = 0; i < num_data_channels; i++) {
+ unsigned int bytes_to_read;
+
+ if (test_bit(i, indio_dev->active_scan_mask)) {
+ bytes_to_read = indio_dev->channels[i].scan_type.storagebits >> 3;
+ len = sdata->tf->read_multiple_byte(&sdata->tb,
+ sdata->dev, indio_dev->channels[i].address,
+ bytes_to_read,
+ buf + total, sdata->multiread_bit);
+
+ if (len < bytes_to_read)
+ return -EIO;
+
+ /* Advance the buffer pointer */
+ total += len;
+ }
}
- return 0;
+ return total;
}
irqreturn_t st_sensors_trigger_handler(int irq, void *p)
diff --git a/drivers/iio/common/st_sensors/st_sensors_core.c b/drivers/iio/common/st_sensors/st_sensors_core.c
index 975a1f19f747..4abe8aca1b29 100644
--- a/drivers/iio/common/st_sensors/st_sensors_core.c
+++ b/drivers/iio/common/st_sensors/st_sensors_core.c
@@ -483,7 +483,7 @@ static int st_sensors_read_axis_data(struct iio_dev *indio_dev,
int err;
u8 *outdata;
struct st_sensor_data *sdata = iio_priv(indio_dev);
- unsigned int byte_for_channel = ch->scan_type.realbits >> 3;
+ unsigned int byte_for_channel = ch->scan_type.storagebits >> 3;
outdata = kmalloc(byte_for_channel, GFP_KERNEL);
if (!outdata)
--
2.9.3
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