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Groups > linux.kernel > #1728837
| From | Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 4.12 15/43] iio: adc: ti-ads1015: add adequate wait time to get correct conversion |
| Date | 2017-09-08 15:30 +0200 |
| Message-ID | <unrw7-7zK-55@gated-at.bofh.it> (permalink) |
| References | <unrw5-7zK-9@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
4.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Akinobu Mita <akinobu.mita@gmail.com>
commit 4744d4e2afebf9644a439da9ca73d822fdd67bd9 upstream.
This driver assumes that the device is operating in the continuous
conversion mode which performs the conversion continuously. So this driver
inserts a wait time before reading the conversion register if the
configuration is changed from a previous request.
Currently, the wait time is only the period required for a single
conversion that is calculated as the reciprocal of the sampling frequency.
However we also need to wait for the the previous conversion to complete.
Otherwise we probably get the conversion result for the previous
configuration when the sampling frequency is lower.
Cc: Daniel Baluta <daniel.baluta@gmail.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/iio/adc/ti-ads1015.c | 31 +++++++++++++++++++------------
1 file changed, 19 insertions(+), 12 deletions(-)
--- a/drivers/iio/adc/ti-ads1015.c
+++ b/drivers/iio/adc/ti-ads1015.c
@@ -242,27 +242,34 @@ static
int ads1015_get_adc_result(struct ads1015_data *data, int chan, int *val)
{
int ret, pga, dr, conv_time;
- bool change;
+ unsigned int old, mask, cfg;
if (chan < 0 || chan >= ADS1015_CHANNELS)
return -EINVAL;
+ ret = regmap_read(data->regmap, ADS1015_CFG_REG, &old);
+ if (ret)
+ return ret;
+
pga = data->channel_data[chan].pga;
dr = data->channel_data[chan].data_rate;
+ mask = ADS1015_CFG_MUX_MASK | ADS1015_CFG_PGA_MASK |
+ ADS1015_CFG_DR_MASK;
+ cfg = chan << ADS1015_CFG_MUX_SHIFT | pga << ADS1015_CFG_PGA_SHIFT |
+ dr << ADS1015_CFG_DR_SHIFT;
- ret = regmap_update_bits_check(data->regmap, ADS1015_CFG_REG,
- ADS1015_CFG_MUX_MASK |
- ADS1015_CFG_PGA_MASK |
- ADS1015_CFG_DR_MASK,
- chan << ADS1015_CFG_MUX_SHIFT |
- pga << ADS1015_CFG_PGA_SHIFT |
- dr << ADS1015_CFG_DR_SHIFT,
- &change);
- if (ret < 0)
+ cfg = (old & ~mask) | (cfg & mask);
+
+ ret = regmap_write(data->regmap, ADS1015_CFG_REG, cfg);
+ if (ret)
return ret;
- if (change || data->conv_invalid) {
- conv_time = DIV_ROUND_UP(USEC_PER_SEC, data->data_rate[dr]);
+ if (old != cfg || data->conv_invalid) {
+ int dr_old = (old & ADS1015_CFG_DR_MASK) >>
+ ADS1015_CFG_DR_SHIFT;
+
+ conv_time = DIV_ROUND_UP(USEC_PER_SEC, data->data_rate[dr_old]);
+ conv_time += DIV_ROUND_UP(USEC_PER_SEC, data->data_rate[dr]);
usleep_range(conv_time, conv_time + 1);
data->conv_invalid = false;
}
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[PATCH 4.12 00/43] 4.12.12-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200 [PATCH 4.12 11/43] iio: adc: ti-ads1015: fix scale information for ADS1115 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200 [PATCH 4.12 15/43] iio: adc: ti-ads1015: add adequate wait time to get correct conversion Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200 [PATCH 4.12 21/43] fpga: altera-hps2fpga: fix multiple init of l3_remap_lock Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200 [PATCH 4.12 43/43] rtlwifi: Fix fallback firmware loading Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200 [PATCH 4.12 25/43] Input: trackpoint - assume 3 buttons when buttons detection fails Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200 [PATCH 4.12 26/43] rtlwifi: rtl_pci_probe: Fix fail path of _rtl_pci_find_adapter Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200 [PATCH 4.12 22/43] intel_th: pci: Add Cannon Lake PCH-H support Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200 [PATCH 4.12 35/43] drm/nouveau: Fix error handling in nv50_disp_atomic_commit Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200 [PATCH 4.12 38/43] cs5536: add support for IDE controller variant Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200 [PATCH 4.12 06/43] ANDROID: binder: add padding to binder_fd_array_object. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200 [PATCH 4.12 08/43] USB: core: Avoid race of async_completed() w/ usbdev_release() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200 [PATCH 4.12 01/43] usb: quirks: add delay init quirk for Corsair Strafe RGB keyboard Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200 [PATCH 4.12 39/43] scsi: sg: protect against races between mmap() and SG_SET_RESERVED_SIZE Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200 [PATCH 4.12 23/43] intel_th: pci: Add Cannon Lake PCH-LP support Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200 [PATCH 4.12 34/43] drm/nouveau/pci/msi: disable MSI on big-endian platforms by default Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:40 +0200 [PATCH 4.12 37/43] ahci: dont use MSI for devices with the silly Intel NVMe remapping scheme Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:40 +0200 [PATCH 4.12 42/43] rtlwifi: Fix memory leak when firmware request fails Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:40 +0200 [PATCH 4.12 32/43] s390/mm: avoid empty zero pages for KVM guests to avoid postcopy hangs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:40 +0200 [PATCH 4.12 28/43] iwlwifi: pci: add new PCI ID for 7265D Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:40 +0200 [PATCH 4.12 24/43] ath10k: fix memory leak in rx ring buffer allocation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:40 +0200 [PATCH 4.12 16/43] driver core: bus: Fix a potential double free Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:40 +0200 [PATCH 4.12 31/43] MCB: add support for SC31 to mcb-lpc Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:40 +0200 [PATCH 4.12 40/43] scsi: sg: recheck MMAP_IO request length with lock held Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:40 +0200 [PATCH 4.12 18/43] binder: free memory on error Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:40 +0200 [PATCH 4.12 17/43] HID: wacom: Do not completely map WACOM_HID_WD_TOUCHRINGSTATUS usage Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:50 +0200 [PATCH 4.12 07/43] ANDROID: binder: add hwbinder,vndbinder to BINDER_DEVICES. 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