From a1a8e1dc111d6f05e7164e851e58219d428359e1 Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Tue, 16 Jul 2013 15:28:00 +0100 Subject: iio:trigger: Fix use_count race condition When using more than one trigger consumer it can happen that multiple threads perform a read-modify-update cycle on 'use_count' concurrently. This can cause updates to be lost and use_count can get stuck at non-zero value, in which case the IIO core assumes that at least one thread is still running and will wait for it to finish before running any trigger handlers again. This effectively renders the trigger disabled and a reboot is necessary before it can be used again. To fix this make use_count an atomic variable. Also set it to the number of consumers before starting the first consumer, otherwise it might happen that use_count drops to 0 even though not all consumers have been run yet. Signed-off-by: Lars-Peter Clausen Tested-by: Denis Ciocca Signed-off-by: Jonathan Cameron --- include/linux/iio/trigger.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/iio/trigger.h b/include/linux/iio/trigger.h index 3869c525b05..369cf2cd514 100644 --- a/include/linux/iio/trigger.h +++ b/include/linux/iio/trigger.h @@ -8,6 +8,7 @@ */ #include #include +#include #ifndef _IIO_TRIGGER_H_ #define _IIO_TRIGGER_H_ @@ -61,7 +62,7 @@ struct iio_trigger { struct list_head list; struct list_head alloc_list; - int use_count; + atomic_t use_count; struct irq_chip subirq_chip; int subirq_base; -- cgit v1.2.3-70-g09d2 From b1451e546899bc8f450773b2af02e0cd000cf1fa Mon Sep 17 00:00:00 2001 From: "Patil, Rachna" Date: Sat, 20 Jul 2013 17:27:00 +0100 Subject: iio: ti_am335x_adc: Fix wrong samples received on 1st read Previously we tried to read data form ADC even before ADC sequencer finished sampling. This led to wrong samples. We now wait on ADC status register idle bit to be set. Signed-off-by: Patil, Rachna Signed-off-by: Zubair Lutfullah Signed-off-by: Jonathan Cameron --- drivers/iio/adc/ti_am335x_adc.c | 30 ++++++++++++++++++++++-------- include/linux/mfd/ti_am335x_tscadc.h | 16 ++++++++++++++++ 2 files changed, 38 insertions(+), 8 deletions(-) (limited to 'include') diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c index 0ad208a69c2..3ceac3e91dd 100644 --- a/drivers/iio/adc/ti_am335x_adc.c +++ b/drivers/iio/adc/ti_am335x_adc.c @@ -60,7 +60,6 @@ static void tiadc_step_config(struct tiadc_device *adc_dev) { unsigned int stepconfig; int i, steps; - u32 step_en; /* * There are 16 configurable steps and 8 analog input @@ -86,8 +85,7 @@ static void tiadc_step_config(struct tiadc_device *adc_dev) adc_dev->channel_step[i] = steps; steps++; } - step_en = get_adc_step_mask(adc_dev); - am335x_tsc_se_set(adc_dev->mfd_tscadc, step_en); + } static const char * const chan_name_ain[] = { @@ -142,10 +140,22 @@ static int tiadc_read_raw(struct iio_dev *indio_dev, int *val, int *val2, long mask) { struct tiadc_device *adc_dev = iio_priv(indio_dev); - int i; - unsigned int fifo1count, read; + int i, map_val; + unsigned int fifo1count, read, stepid; u32 step = UINT_MAX; bool found = false; + u32 step_en; + unsigned long timeout = jiffies + usecs_to_jiffies + (IDLE_TIMEOUT * adc_dev->channels); + step_en = get_adc_step_mask(adc_dev); + am335x_tsc_se_set(adc_dev->mfd_tscadc, step_en); + + /* Wait for ADC sequencer to complete sampling */ + while (tiadc_readl(adc_dev, REG_ADCFSM) & SEQ_STATUS) { + if (time_after(jiffies, timeout)) + return -EAGAIN; + } + map_val = chan->channel + TOTAL_CHANNELS; /* * When the sub-system is first enabled, @@ -170,12 +180,16 @@ static int tiadc_read_raw(struct iio_dev *indio_dev, fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT); for (i = 0; i < fifo1count; i++) { read = tiadc_readl(adc_dev, REG_FIFO1); - if (read >> 16 == step) { - *val = read & 0xfff; + stepid = read & FIFOREAD_CHNLID_MASK; + stepid = stepid >> 0x10; + + if (stepid == map_val) { + read = read & FIFOREAD_DATA_MASK; found = true; + *val = read; } } - am335x_tsc_se_update(adc_dev->mfd_tscadc); + if (found == false) return -EBUSY; return IIO_VAL_INT; diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h index 8d73fe29796..db1791bb997 100644 --- a/include/linux/mfd/ti_am335x_tscadc.h +++ b/include/linux/mfd/ti_am335x_tscadc.h @@ -113,11 +113,27 @@ #define CNTRLREG_8WIRE CNTRLREG_AFE_CTRL(3) #define CNTRLREG_TSCENB BIT(7) +/* FIFO READ Register */ +#define FIFOREAD_DATA_MASK (0xfff << 0) +#define FIFOREAD_CHNLID_MASK (0xf << 16) + +/* Sequencer Status */ +#define SEQ_STATUS BIT(5) + #define ADC_CLK 3000000 #define MAX_CLK_DIV 7 #define TOTAL_STEPS 16 #define TOTAL_CHANNELS 8 +/* +* ADC runs at 3MHz, and it takes +* 15 cycles to latch one data output. +* Hence the idle time for ADC to +* process one sample data would be +* around 5 micro seconds. +*/ +#define IDLE_TIMEOUT 5 /* microsec */ + #define TSCADC_CELLS 2 struct ti_tscadc_dev { -- cgit v1.2.3-70-g09d2