Hi Andreas, On Thu, Aug 24, 2017 at 10:52 PM, Andreas Klinger <ak@xxxxxxxxxxxxx> wrote: > Hi Colin, > > Colin Parker <colin.foeparker@xxxxxxxxx> schrieb am Thu, 24. Aug 16:54: >> From: Colin Parker <colin.parker@xxxxxxxxx> >> >> This results in inaccurate Humidity readings that tend to not fluxuate. >> >> Update the ordering of the register writes so that ctrl_meas is written >> after ctrl_hum. This is taken from section 5.4.3 of the datasheet. >> >> "https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BME280_DS001-11.pdf"; > > this part of the patch is already covered by commit afb2c3851b: "iio: bmp280: > properly initialize device for humidity reading" Thanks for pointing out the duplication of efforts! I dug through the fixes-togreg branch and found the changes you are referencing. I think that there might still be an issue there. I believe that the regmap_update_bits function will only write to the ctrl_meas register if there is a difference in the register value vs what is in the regmap cache. So in the situation where someone wanted to update the humidity sampling configuration, I don't think the write to the ctrl_meas write would go out on the bus. And as a consequence, the changes to the humidity settings wouldn't become effective. What is your take? I can refactor my patch to just fix that part if you see the same bug. -Colin > > Andreas > >> >> Also writes to the config register can be ignored if the device is in Normal Mode. >> Change the device to sleep mode before updating the config register. >> This has the nice side effect of guaranteeing that the regmap_update_bits >> function actually updates the driver and not just verifies the setting in its cache. >> >> Signed-off-by: Colin Parker <colin.parker@xxxxxxxxx> >> --- >> drivers/iio/pressure/bmp280-core.c | 22 +++++++++++++++------- >> 1 file changed, 15 insertions(+), 7 deletions(-) >> >> diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c >> index d82b788..85aa24c 100644 >> --- a/drivers/iio/pressure/bmp280-core.c >> +++ b/drivers/iio/pressure/bmp280-core.c >> @@ -559,10 +559,7 @@ static int bmp280_chip_config(struct bmp280_data *data) >> BMP280_OSRS_PRESS_X(data->oversampling_press + 1); >> >> ret = regmap_update_bits(data->regmap, BMP280_REG_CTRL_MEAS, >> - BMP280_OSRS_TEMP_MASK | >> - BMP280_OSRS_PRESS_MASK | >> - BMP280_MODE_MASK, >> - osrs | BMP280_MODE_NORMAL); >> + BMP280_MODE_MASK, BMP280_MODE_SLEEP); >> if (ret < 0) { >> dev_err(data->dev, >> "failed to write ctrl_meas register\n"); >> @@ -578,6 +575,17 @@ static int bmp280_chip_config(struct bmp280_data *data) >> return ret; >> } >> >> + ret = regmap_update_bits(data->regmap, BMP280_REG_CTRL_MEAS, >> + BMP280_OSRS_TEMP_MASK | >> + BMP280_OSRS_PRESS_MASK | >> + BMP280_MODE_MASK, >> + osrs | BMP280_MODE_NORMAL); >> + if (ret < 0) { >> + dev_err(data->dev, >> + "failed to write ctrl_meas register\n"); >> + return ret; >> + } >> + >> return ret; >> } >> >> @@ -597,14 +605,14 @@ static const struct bmp280_chip_info bmp280_chip_info = { >> >> static int bme280_chip_config(struct bmp280_data *data) >> { >> - int ret = bmp280_chip_config(data); >> u8 osrs = BMP280_OSRS_HUMIDITIY_X(data->oversampling_humid + 1); >> + int ret = regmap_update_bits(data->regmap, BMP280_REG_CTRL_HUMIDITY, >> + BMP280_OSRS_HUMIDITY_MASK, osrs); >> >> if (ret < 0) >> return ret; >> >> - return regmap_update_bits(data->regmap, BMP280_REG_CTRL_HUMIDITY, >> - BMP280_OSRS_HUMIDITY_MASK, osrs); >> + return bmp280_chip_config(data); >> } >> >> static const struct bmp280_chip_info bme280_chip_info = { >> -- >> 2.1.4 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-iio" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- -- Colin Parker ACLIMA INC Direct (415) 735-5062 | Email colin.foeparker@xxxxxxxxx 10 Lombard St. Suite 250 | San Francisco, CA 94111 Hello, we're Aclima. This email and any attachments may contain private, confidential and privileged material for the sole use of the intended recipient. If you are not the intended recipient, please immediately delete this email and any attachments. -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
