On Wed, 18 May 2022 at 14:48, Eddie James <eajames@xxxxxxxxxxxxx> wrote:
Corruption of the MEAS_CFG register has been observed soon afterI have some suggestions below on how to rework to make the code easier
system boot. In order to recover this scenario, check MEAS_CFG if
measurement isn't ready, and if it's incorrect, reset the DPS310
and execute the startup procedure.
to understand. But before we got to that, I had some high level
questions:
You don't seem to be setting the en bits in the CFG register after
doing the reset. Is that required?
Are we ok to sleep for 2.5ms in the iio_info->read_raw callback?
Fixes: ba6ec48e76bc ("iio: Add driver for Infineon DPS310")Perhaps add this to your comment: Returns a negative value on error, a
Signed-off-by: Eddie James <eajames@xxxxxxxxxxxxx>
---
drivers/iio/pressure/dps310.c | 89 ++++++++++++++++++++++++++++-------
1 file changed, 71 insertions(+), 18 deletions(-)
diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c
index f79b274bb38d..c6d02679ef33 100644
--- a/drivers/iio/pressure/dps310.c
+++ b/drivers/iio/pressure/dps310.c
@@ -397,6 +397,39 @@ static int dps310_get_temp_k(struct dps310_data *data)
return scale_factors[ilog2(rc)];
}
+/* Called with lock held */
positive value when the device is not ready (and may have been reset
due to corruption), and zero when the device is ready.
+static int dps310_check_reset_meas_cfg(struct dps310_data *data, int ready_bit)I'm confused about this case. We get there when the device doesn't
+{
+ int en = DPS310_PRS_EN | DPS310_TEMP_EN | DPS310_BACKGROUND;
+ int meas_cfg;
+ int rc = regmap_read(data->regmap, DPS310_MEAS_CFG, &meas_cfg);
+
+ if (rc < 0)
+ return rc;
+
+ if (meas_cfg & ready_bit)
+ return 0;
+
+ if ((meas_cfg & en) != en) {
+ /* DPS310 register state corrupt, better start from scratch */
+ rc = regmap_write(data->regmap, DPS310_RESET,
+ DPS310_RESET_MAGIC);
+ if (rc < 0)
+ return rc;
+
+ /* Wait for device chip access: 2.5ms in specification */
+ usleep_range(2500, 12000);
+ rc = dps310_startup(data);
+ if (rc)
+ return rc;
+
+ dev_info(&data->client->dev,
+ "recovered from corrupted MEAS_CFG=%02x\n", meas_cfg);
+ }
+
+ return 1;
have ready_bit set in meas_cfg and we've done a reset, but we also get
here when the bit isn't set and we haven't done anything to resolve it
(after re-reading the code I understand now, but perhaps reworking it
as follows will make it clear):
Could we write it like this:
if (meas_cfg & ready_bit) {
/* Device ready, must be okay */
return 0;
}
if (meas_cfg & en) {
/* Device okay (but not ready), no action required */
return 1;
}
/* DPS310 register state corrupt, better start from scratch */
...
return 1;
+}can we do this:
+
static int dps310_read_pres_raw(struct dps310_data *data)
{
int rc;
@@ -409,15 +442,25 @@ static int dps310_read_pres_raw(struct dps310_data *data)
if (mutex_lock_interruptible(&data->lock))
return -EINTR;
- rate = dps310_get_pres_samp_freq(data);
- timeout = DPS310_POLL_TIMEOUT_US(rate);
-
- /* Poll for sensor readiness; base the timeout upon the sample rate. */
- rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
- ready & DPS310_PRS_RDY,
- DPS310_POLL_SLEEP_US(timeout), timeout);
- if (rc)
- goto done;
+ rc = dps310_check_reset_meas_cfg(data, DPS310_PRS_RDY);
if (rc < 0)
goto done;
if (rc > 0) {
}
The rework I suggest makes it clearer that we've considered the '0'
case, when the device is ready before this code runs.
+ if (rc) {
+ if (rc < 0)
+ goto done;
+
+ rate = dps310_get_pres_samp_freq(data);
+ timeout = DPS310_POLL_TIMEOUT_US(rate);
+
+ /*
+ * Poll for sensor readiness; base the timeout upon the sample
+ * rate.
+ */
+ rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG,
+ ready, ready & DPS310_PRS_RDY,
+ DPS310_POLL_SLEEP_US(timeout),
+ timeout);
+ if (rc)
+ goto done;
+ }
rc = regmap_bulk_read(data->regmap, DPS310_PRS_BASE, val, sizeof(val));
if (rc < 0)
@@ -458,15 +501,25 @@ static int dps310_read_temp_raw(struct dps310_data *data)
if (mutex_lock_interruptible(&data->lock))
return -EINTR;
- rate = dps310_get_temp_samp_freq(data);
- timeout = DPS310_POLL_TIMEOUT_US(rate);
-
- /* Poll for sensor readiness; base the timeout upon the sample rate. */
- rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
- ready & DPS310_TMP_RDY,
- DPS310_POLL_SLEEP_US(timeout), timeout);
- if (rc < 0)
- goto done;
+ rc = dps310_check_reset_meas_cfg(data, DPS310_TMP_RDY);
+ if (rc) {
+ if (rc < 0)
+ goto done;
+
+ rate = dps310_get_temp_samp_freq(data);
+ timeout = DPS310_POLL_TIMEOUT_US(rate);
+
+ /*
+ * Poll for sensor readiness; base the timeout upon the sample
+ * rate.
+ */
+ rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG,
+ ready, ready & DPS310_TMP_RDY,
+ DPS310_POLL_SLEEP_US(timeout),
+ timeout);
+ if (rc < 0)
+ goto done;
+ }
rc = dps310_read_temp_ready(data);
--
2.27.0