| Message ID | 20220120010246.3794962-5-robert.hancock@calian.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Xilinx AMS fixes | expand |
On Wed, 19 Jan 2022 19:02:46 -0600 Robert Hancock <robert.hancock@calian.com> wrote: > Some of the AMS channels need to be read by switching into single-channel > mode from the normal polling sequence. There was a logic issue in this > switching code that could cause the first read of these channels to read > back as zero. > > It appears that the sequencer should be set back to default mode before > changing the channel selection, and the channel should be set before > switching the sequencer back into single-channel mode. > > Also, write 1 to the EOC bit in the status register to clear it before > waiting for it to become set, so that we actually wait for a new > conversion to complete, and don't proceed based on a previous conversion > completing. > > Fixes: d5c70627a794 ("iio: adc: Add Xilinx AMS driver") > Signed-off-by: Robert Hancock <robert.hancock@calian.com> Looking for an Ack from Anand or someone else familiar with this device. Thanks, Jonathan > --- > drivers/iio/adc/xilinx-ams.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/drivers/iio/adc/xilinx-ams.c b/drivers/iio/adc/xilinx-ams.c > index 199027c93cdc..7bf097fa10cb 100644 > --- a/drivers/iio/adc/xilinx-ams.c > +++ b/drivers/iio/adc/xilinx-ams.c > @@ -530,14 +530,18 @@ static int ams_enable_single_channel(struct ams *ams, unsigned int offset) > return -EINVAL; > } > > - /* set single channel, sequencer off mode */ > + /* put sysmon in a soft reset to change the sequence */ > ams_ps_update_reg(ams, AMS_REG_CONFIG1, AMS_CONF1_SEQ_MASK, > - AMS_CONF1_SEQ_SINGLE_CHANNEL); > + AMS_CONF1_SEQ_DEFAULT); > > /* write the channel number */ > ams_ps_update_reg(ams, AMS_REG_CONFIG0, AMS_CONF0_CHANNEL_NUM_MASK, > channel_num); > > + /* set single channel, sequencer off mode */ > + ams_ps_update_reg(ams, AMS_REG_CONFIG1, AMS_CONF1_SEQ_MASK, > + AMS_CONF1_SEQ_SINGLE_CHANNEL); > + > return 0; > } > > @@ -551,6 +555,8 @@ static int ams_read_vcc_reg(struct ams *ams, unsigned int offset, u32 *data) > if (ret) > return ret; > > + /* clear end-of-conversion flag, wait for next conversion to complete */ > + writel(expect, ams->base + AMS_ISR_1); > ret = readl_poll_timeout(ams->base + AMS_ISR_1, reg, (reg & expect), > AMS_INIT_POLL_TIME_US, AMS_INIT_TIMEOUT_US); > if (ret)
diff --git a/drivers/iio/adc/xilinx-ams.c b/drivers/iio/adc/xilinx-ams.c index 199027c93cdc..7bf097fa10cb 100644 --- a/drivers/iio/adc/xilinx-ams.c +++ b/drivers/iio/adc/xilinx-ams.c @@ -530,14 +530,18 @@ static int ams_enable_single_channel(struct ams *ams, unsigned int offset) return -EINVAL; } - /* set single channel, sequencer off mode */ + /* put sysmon in a soft reset to change the sequence */ ams_ps_update_reg(ams, AMS_REG_CONFIG1, AMS_CONF1_SEQ_MASK, - AMS_CONF1_SEQ_SINGLE_CHANNEL); + AMS_CONF1_SEQ_DEFAULT); /* write the channel number */ ams_ps_update_reg(ams, AMS_REG_CONFIG0, AMS_CONF0_CHANNEL_NUM_MASK, channel_num); + /* set single channel, sequencer off mode */ + ams_ps_update_reg(ams, AMS_REG_CONFIG1, AMS_CONF1_SEQ_MASK, + AMS_CONF1_SEQ_SINGLE_CHANNEL); + return 0; } @@ -551,6 +555,8 @@ static int ams_read_vcc_reg(struct ams *ams, unsigned int offset, u32 *data) if (ret) return ret; + /* clear end-of-conversion flag, wait for next conversion to complete */ + writel(expect, ams->base + AMS_ISR_1); ret = readl_poll_timeout(ams->base + AMS_ISR_1, reg, (reg & expect), AMS_INIT_POLL_TIME_US, AMS_INIT_TIMEOUT_US); if (ret)
Some of the AMS channels need to be read by switching into single-channel mode from the normal polling sequence. There was a logic issue in this switching code that could cause the first read of these channels to read back as zero. It appears that the sequencer should be set back to default mode before changing the channel selection, and the channel should be set before switching the sequencer back into single-channel mode. Also, write 1 to the EOC bit in the status register to clear it before waiting for it to become set, so that we actually wait for a new conversion to complete, and don't proceed based on a previous conversion completing. Fixes: d5c70627a794 ("iio: adc: Add Xilinx AMS driver") Signed-off-by: Robert Hancock <robert.hancock@calian.com> --- drivers/iio/adc/xilinx-ams.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)