[PATCH V9 0/2] iio: input: ti_am335x_adc: Add continuous sampling support

[PATCH V9 0/2] iio: input: ti_am335x_adc: Add continuous sampling support

[Zubair Lutfullah]

Hi,

This applies to togreg branch in iio.

Round 9 updates

- Removed Trigger.
- Restructured everything for INDIO_BUFFERED_HARDWARE mode.
- Threaded IRQ with top/bottom halfs. Top half HW IRQ wakes
bottom half threaded worker that pushes samples to iio/userspace.
- Removed some of the patchwork to the driver that was irrelevant to the
continuous sampling patch.

Cleanup will be done separately once this goes through.
Hope these patches meet the mighty kernel standards :)

Zubair

Zubair Lutfullah (2):
  input: ti_am335x_tsc: Enable shared IRQ for TSC
  iio: ti_am335x_adc: Add continuous sampling support

 drivers/iio/adc/ti_am335x_adc.c           |  222 ++++++++++++++++++++++++++++-
 drivers/input/touchscreen/ti_am335x_tsc.c |   12 +-
 include/linux/mfd/ti_am335x_tscadc.h      |    9 ++
 3 files changed, 235 insertions(+), 8 deletions(-)

-- 
1.7.9.5

[PATCH 1/2] input: ti_am335x_tsc: Enable shared IRQ for TSC

[Zubair Lutfullah]

Enable shared IRQ to allow ADC to share IRQ line from
parent MFD core. Only FIFO0 IRQs are for TSC and handled
on the TSC side.

Step mask would be updated from cached variable only previously.
In rare cases when both TSC and ADC are used, the cached
variable gets mixed up.
The step mask is written with the required mask every time.

Rachna Patil (TI) laid ground work for shared IRQ.

Signed-off-by: Zubair Lutfullah <zubair.lutfullah@gmail.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 drivers/input/touchscreen/ti_am335x_tsc.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/input/touchscreen/ti_am335x_tsc.c b/drivers/input/touchscreen/ti_am335x_tsc.c
index e1c5300..24e625c 100644
--- a/drivers/input/touchscreen/ti_am335x_tsc.c
+++ b/drivers/input/touchscreen/ti_am335x_tsc.c
@@ -52,6 +52,7 @@ struct titsc {
 	u32			config_inp[4];
 	u32			bit_xp, bit_xn, bit_yp, bit_yn;
 	u32			inp_xp, inp_xn, inp_yp, inp_yn;
+	u32			step_mask;
 };
 
 static unsigned int titsc_readl(struct titsc *ts, unsigned int reg)
@@ -196,7 +197,8 @@ static void titsc_step_config(struct titsc *ts_dev)
 
 	/* The steps1 … end and bit 0 for TS_Charge */
 	stepenable = (1 << (end_step + 2)) - 1;
-	am335x_tsc_se_set(ts_dev->mfd_tscadc, stepenable);
+	ts_dev->step_mask = stepenable;
+	am335x_tsc_se_set(ts_dev->mfd_tscadc, ts_dev->step_mask);
 }
 
 static void titsc_read_coordinates(struct titsc *ts_dev,
@@ -260,6 +262,10 @@ static irqreturn_t titsc_irq(int irq, void *dev)
 	unsigned int fsm;
 
 	status = titsc_readl(ts_dev, REG_IRQSTATUS);
+	/*
+	 * ADC and touchscreen share the IRQ line.
+	 * FIFO1 interrupts are used by ADC. Handle FIFO0 IRQs here only
+	 */
 	if (status & IRQENB_FIFO0THRES) {
 
 		titsc_read_coordinates(ts_dev, &x, &y, &z1, &z2);
@@ -316,7 +322,7 @@ static irqreturn_t titsc_irq(int irq, void *dev)
 
 	if (irqclr) {
 		titsc_writel(ts_dev, REG_IRQSTATUS, irqclr);
-		am335x_tsc_se_update(ts_dev->mfd_tscadc);
+		am335x_tsc_se_set(ts_dev->mfd_tscadc, ts_dev->step_mask);
 		return IRQ_HANDLED;
 	}
 	return IRQ_NONE;
@@ -389,7 +395,7 @@ static int titsc_probe(struct platform_device *pdev)
 	}
 
 	err = request_irq(ts_dev->irq, titsc_irq,
-			  0, pdev->dev.driver->name, ts_dev);
+			  IRQF_SHARED, pdev->dev.driver->name, ts_dev);
 	if (err) {
 		dev_err(&pdev->dev, "failed to allocate irq.\n");
 		goto err_free_mem;
-- 
1.7.9.5

[PATCH 2/2] iio: ti_am335x_adc: Add continuous sampling support

[Zubair Lutfullah]

Previously the driver had only one-shot reading functionality.
This patch adds continuous sampling support to the driver.

Continuous sampling starts when buffer is enabled.
HW IRQ wakes worker thread that pushes samples to userspace.
Sampling stops when buffer is disabled by userspace.

Patil Rachna (TI) laid the ground work for ADC HW register access.
Russ Dill (TI) fixed bugs in the driver relevant to FIFOs and IRQs.

I fixed channel scanning so multiple ADC channels can be read
simultaneously and pushed to userspace.
Restructured the driver to fit IIO ABI.
And added INDIO_BUFFER_HARDWARE mode.

Signed-off-by: Zubair Lutfullah <zubair.lutfullah@gmail.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Russ Dill <Russ.Dill@ti.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/iio/adc/ti_am335x_adc.c      |  222 +++++++++++++++++++++++++++++++++-
 include/linux/mfd/ti_am335x_tscadc.h |    9 ++
 2 files changed, 226 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
index a952538..fa916f3 100644
--- a/drivers/iio/adc/ti_am335x_adc.c
+++ b/drivers/iio/adc/ti_am335x_adc.c
@@ -28,12 +28,19 @@
 #include <linux/iio/driver.h>
 
 #include <linux/mfd/ti_am335x_tscadc.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/kfifo_buf.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
 
 struct tiadc_device {
 	struct ti_tscadc_dev *mfd_tscadc;
 	int channels;
 	u8 channel_line[8];
 	u8 channel_step[8];
+	int buffer_en_ch_steps;
+	u32 *data;
 };
 
 static unsigned int tiadc_readl(struct tiadc_device *adc, unsigned int reg)
@@ -56,8 +63,14 @@ static u32 get_adc_step_mask(struct tiadc_device *adc_dev)
 	return step_en;
 }
 
-static void tiadc_step_config(struct tiadc_device *adc_dev)
+static u32 get_adc_step_bit(struct tiadc_device *adc_dev, int chan)
 {
+	return 1 << adc_dev->channel_step[chan];
+}
+
+static void tiadc_step_config(struct iio_dev *indio_dev)
+{
+	struct tiadc_device *adc_dev = iio_priv(indio_dev);
 	unsigned int stepconfig;
 	int i, steps;
 
@@ -72,7 +85,11 @@ static void tiadc_step_config(struct tiadc_device *adc_dev)
 	 */
 
 	steps = TOTAL_STEPS - adc_dev->channels;
-	stepconfig = STEPCONFIG_AVG_16 | STEPCONFIG_FIFO1;
+	if (iio_buffer_enabled(indio_dev))
+		stepconfig = STEPCONFIG_AVG_16 | STEPCONFIG_FIFO1
+					| STEPCONFIG_MODE_SWCNT;
+	else
+		stepconfig = STEPCONFIG_AVG_16 | STEPCONFIG_FIFO1;
 
 	for (i = 0; i < adc_dev->channels; i++) {
 		int chan;
@@ -85,7 +102,183 @@ static void tiadc_step_config(struct tiadc_device *adc_dev)
 		adc_dev->channel_step[i] = steps;
 		steps++;
 	}
+}
+
+static irqreturn_t tiadc_irq_h(int irq, void *private)
+{
+	struct iio_dev *indio_dev = private;
+	struct tiadc_device *adc_dev = iio_priv(indio_dev);
+	unsigned int status, config;
+	status = tiadc_readl(adc_dev, REG_IRQSTATUS);
+
+	/*
+	 * ADC and touchscreen share the IRQ line.
+	 * FIFO0 interrupts are used by TSC. Handle FIFO1 IRQs here only
+	 */
+	if (status & IRQENB_FIFO1OVRRUN) {
+		/* FIFO Overrun. Clear flag. Disable/Enable ADC to recover */
+		config = tiadc_readl(adc_dev, REG_CTRL);
+		config &= ~(CNTRLREG_TSCSSENB);
+		tiadc_writel(adc_dev, REG_CTRL, config);
+		tiadc_writel(adc_dev, REG_IRQSTATUS, IRQENB_FIFO1OVRRUN
+				| IRQENB_FIFO1UNDRFLW | IRQENB_FIFO1THRES);
+		tiadc_writel(adc_dev, REG_CTRL, (config | CNTRLREG_TSCSSENB));
+		return IRQ_HANDLED;
+	} else if (status & IRQENB_FIFO1THRES) {
+		/* Disable irq and wake worker thread */
+		tiadc_writel(adc_dev, REG_IRQCLR, IRQENB_FIFO1THRES);
+		return IRQ_WAKE_THREAD;
+	}
+
+	return IRQ_NONE;
+}
+
+static irqreturn_t tiadc_worker_h(int irq, void *private)
+{
+	struct iio_dev *indio_dev = private;
+	struct tiadc_device *adc_dev = iio_priv(indio_dev);
+	int i, k, fifo1count, read;
+	u32 *data = adc_dev->data;
+
+	fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
+	for (k = 0; k < fifo1count; k = k + i) {
+		for (i = 0; i < (indio_dev->scan_bytes)/4; i++) {
+			read = tiadc_readl(adc_dev, REG_FIFO1);
+			data[i] = read & FIFOREAD_DATA_MASK;
+		}
+		iio_push_to_buffers(indio_dev, (u8 *) data);
+	}
+
+	tiadc_writel(adc_dev, REG_IRQSTATUS, IRQENB_FIFO1THRES);
+	tiadc_writel(adc_dev, REG_IRQENABLE, IRQENB_FIFO1THRES);
 
+	return IRQ_HANDLED;
+}
+
+static int tiadc_buffer_preenable(struct iio_dev *indio_dev)
+{
+	struct tiadc_device *adc_dev = iio_priv(indio_dev);
+	int i, fifo1count, read;
+
+	tiadc_writel(adc_dev, REG_IRQCLR, (IRQENB_FIFO1THRES |
+				IRQENB_FIFO1OVRRUN |
+				IRQENB_FIFO1UNDRFLW));
+
+	/* Flush FIFO. Needed in corner cases in simultaneous tsc/adc use */
+	fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
+	for (i = 0; i < fifo1count; i++)
+		read = tiadc_readl(adc_dev, REG_FIFO1);
+
+	return iio_sw_buffer_preenable(indio_dev);
+}
+
+static int tiadc_buffer_postenable(struct iio_dev *indio_dev)
+{
+	struct tiadc_device *adc_dev = iio_priv(indio_dev);
+	struct iio_buffer *buffer = indio_dev->buffer;
+	unsigned int enb = 0;
+	u8 bit;
+
+	adc_dev->data = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
+	if (adc_dev->data == NULL)
+		return -ENOMEM;
+
+	tiadc_step_config(indio_dev);
+	for_each_set_bit(bit, buffer->scan_mask, adc_dev->channels)
+		enb |= (get_adc_step_bit(adc_dev, bit) << 1);
+	adc_dev->buffer_en_ch_steps = enb;
+
+	am335x_tsc_se_set(adc_dev->mfd_tscadc, enb);
+
+	tiadc_writel(adc_dev,  REG_IRQSTATUS, IRQENB_FIFO1THRES
+				| IRQENB_FIFO1OVRRUN | IRQENB_FIFO1UNDRFLW);
+	tiadc_writel(adc_dev,  REG_IRQENABLE, IRQENB_FIFO1THRES
+				| IRQENB_FIFO1OVRRUN);
+
+	return 0;
+}
+
+static int tiadc_buffer_predisable(struct iio_dev *indio_dev)
+{
+	struct tiadc_device *adc_dev = iio_priv(indio_dev);
+	int fifo1count, i, read;
+
+	tiadc_writel(adc_dev, REG_IRQCLR, (IRQENB_FIFO1THRES |
+				IRQENB_FIFO1OVRRUN | IRQENB_FIFO1UNDRFLW));
+	am335x_tsc_se_clr(adc_dev->mfd_tscadc, adc_dev->buffer_en_ch_steps);
+
+	/* Flush FIFO of leftover data in the time it takes to disable adc */
+	fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
+	for (i = 0; i < fifo1count; i++)
+		read = tiadc_readl(adc_dev, REG_FIFO1);
+
+	return 0;
+}
+
+static int tiadc_buffer_postdisable(struct iio_dev *indio_dev)
+{
+	struct tiadc_device *adc_dev = iio_priv(indio_dev);
+
+	tiadc_step_config(indio_dev);
+	kfree(adc_dev->data);
+
+	return 0;
+}
+
+static const struct iio_buffer_setup_ops tiadc_buffer_setup_ops = {
+	.preenable = &tiadc_buffer_preenable,
+	.postenable = &tiadc_buffer_postenable,
+	.predisable = &tiadc_buffer_predisable,
+	.postdisable = &tiadc_buffer_postdisable,
+};
+
+int tiadc_iio_buffered_hardware_setup(struct iio_dev *indio_dev,
+	irqreturn_t (*pollfunc_bh)(int irq, void *p),
+	irqreturn_t (*pollfunc_th)(int irq, void *p),
+	int irq,
+	unsigned long flags,
+	const struct iio_buffer_setup_ops *setup_ops)
+{
+	int ret;
+
+	indio_dev->buffer = iio_kfifo_allocate(indio_dev);
+	if (!indio_dev->buffer)
+		return -ENOMEM;
+
+	ret = devm_request_threaded_irq(indio_dev->dev.parent,
+				irq,
+				pollfunc_th, pollfunc_bh,
+				flags, indio_dev->name,
+				indio_dev);
+	if (ret)
+		goto error_kfifo_free;
+
+	indio_dev->setup_ops = setup_ops;
+	indio_dev->modes |= INDIO_BUFFER_HARDWARE;
+
+	ret = iio_buffer_register(indio_dev,
+				  indio_dev->channels,
+				  indio_dev->num_channels);
+	if (ret)
+		goto error_free_irq;
+
+	return 0;
+
+error_free_irq:
+	devm_free_irq(indio_dev->dev.parent, irq, indio_dev);
+error_kfifo_free:
+	iio_kfifo_free(indio_dev->buffer);
+	return ret;
+}
+
+static void tiadc_iio_buffered_hardware_remove(struct iio_dev *indio_dev)
+{
+	struct tiadc_device *adc_dev = iio_priv(indio_dev);
+
+	devm_free_irq(indio_dev->dev.parent,
+			adc_dev->mfd_tscadc->irq, indio_dev);
+	iio_kfifo_free(indio_dev->buffer);
+	iio_buffer_unregister(indio_dev);
 }
 
 static const char * const chan_name_ain[] = {
@@ -120,6 +313,7 @@ static int tiadc_channel_init(struct iio_dev *indio_dev, int channels)
 		chan->channel = adc_dev->channel_line[i];
 		chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
 		chan->datasheet_name = chan_name_ain[chan->channel];
+		chan->scan_index = i;
 		chan->scan_type.sign = 'u';
 		chan->scan_type.realbits = 12;
 		chan->scan_type.storagebits = 32;
@@ -147,6 +341,10 @@ static int tiadc_read_raw(struct iio_dev *indio_dev,
 	u32 step_en;
 	unsigned long timeout = jiffies + usecs_to_jiffies
 				(IDLE_TIMEOUT * adc_dev->channels);
+
+	if (iio_buffer_enabled(indio_dev))
+		return -EBUSY;
+
 	step_en = get_adc_step_mask(adc_dev);
 	am335x_tsc_se_set(adc_dev->mfd_tscadc, step_en);
 
@@ -237,20 +435,33 @@ static int tiadc_probe(struct platform_device *pdev)
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->info = &tiadc_info;
 
-	tiadc_step_config(adc_dev);
+	tiadc_step_config(indio_dev);
+	tiadc_writel(adc_dev, REG_FIFO1THR, FIFO1_THRESHOLD);
 
 	err = tiadc_channel_init(indio_dev, adc_dev->channels);
 	if (err < 0)
 		return err;
 
-	err = iio_device_register(indio_dev);
+	err = tiadc_iio_buffered_hardware_setup(indio_dev,
+		&tiadc_worker_h,
+		&tiadc_irq_h,
+		adc_dev->mfd_tscadc->irq,
+		IRQF_SHARED,
+		&tiadc_buffer_setup_ops);
+
 	if (err)
 		goto err_free_channels;
 
+	err = iio_device_register(indio_dev);
+	if (err)
+		goto err_buffer_unregister;
+
 	platform_set_drvdata(pdev, indio_dev);
 
 	return 0;
 
+err_buffer_unregister:
+	tiadc_iio_buffered_hardware_remove(indio_dev);
 err_free_channels:
 	tiadc_channels_remove(indio_dev);
 	return err;
@@ -263,6 +474,7 @@ static int tiadc_remove(struct platform_device *pdev)
 	u32 step_en;
 
 	iio_device_unregister(indio_dev);
+	tiadc_iio_buffered_hardware_remove(indio_dev);
 	tiadc_channels_remove(indio_dev);
 
 	step_en = get_adc_step_mask(adc_dev);
@@ -301,7 +513,7 @@ static int tiadc_resume(struct device *dev)
 	restore &= ~(CNTRLREG_POWERDOWN);
 	tiadc_writel(adc_dev, REG_CTRL, restore);
 
-	tiadc_step_config(adc_dev);
+	tiadc_step_config(indio_dev);
 
 	return 0;
 }
diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h
index db1791b..7d98562 100644
--- a/include/linux/mfd/ti_am335x_tscadc.h
+++ b/include/linux/mfd/ti_am335x_tscadc.h
@@ -46,16 +46,24 @@
 /* Step Enable */
 #define STEPENB_MASK		(0x1FFFF << 0)
 #define STEPENB(val)		((val) << 0)
+#define ENB(val)			(1 << (val))
+#define STPENB_STEPENB		STEPENB(0x1FFFF)
+#define STPENB_STEPENB_TC	STEPENB(0x1FFF)
 
 /* IRQ enable */
 #define IRQENB_HW_PEN		BIT(0)
 #define IRQENB_FIFO0THRES	BIT(2)
+#define IRQENB_FIFO0OVRRUN	BIT(3)
+#define IRQENB_FIFO0UNDRFLW	BIT(4)
 #define IRQENB_FIFO1THRES	BIT(5)
+#define IRQENB_FIFO1OVRRUN	BIT(6)
+#define IRQENB_FIFO1UNDRFLW	BIT(7)
 #define IRQENB_PENUP		BIT(9)
 
 /* Step Configuration */
 #define STEPCONFIG_MODE_MASK	(3 << 0)
 #define STEPCONFIG_MODE(val)	((val) << 0)
+#define STEPCONFIG_MODE_SWCNT	STEPCONFIG_MODE(1)
 #define STEPCONFIG_MODE_HWSYNC	STEPCONFIG_MODE(2)
 #define STEPCONFIG_AVG_MASK	(7 << 2)
 #define STEPCONFIG_AVG(val)	((val) << 2)
@@ -124,6 +132,7 @@
 #define	MAX_CLK_DIV		7
 #define TOTAL_STEPS		16
 #define TOTAL_CHANNELS		8
+#define FIFO1_THRESHOLD		19
 
 /*
 * ADC runs at 3MHz, and it takes
-- 
1.7.9.5

Re: [PATCH 2/2] iio: ti_am335x_adc: Add continuous sampling support

[Dmitry Torokhov]

Hi Zubair,

On Tue, Sep 17, 2013 at 09:44:07AM +0500, Zubair Lutfullah wrote:
> +
> +	ret = devm_request_threaded_irq(indio_dev->dev.parent,
> +				irq,
> +				pollfunc_th, pollfunc_bh,
> +				flags, indio_dev->name,
> +				indio_dev);
> +	if (ret)
> +		goto error_kfifo_free;
> +
> +	indio_dev->setup_ops = setup_ops;
> +	indio_dev->modes |= INDIO_BUFFER_HARDWARE;
> +
> +	ret = iio_buffer_register(indio_dev,
> +				  indio_dev->channels,
> +				  indio_dev->num_channels);
> +	if (ret)
> +		goto error_free_irq;
> +
> +	return 0;
> +
> +error_free_irq:
> +	devm_free_irq(indio_dev->dev.parent, irq, indio_dev);

What is the point of using devm_* here if you are doing explicit
management of the resource anyway (you explicitly release it in all code
paths)?

Thanks.

-- 
Dmitry

Re: [PATCH 2/2] iio: ti_am335x_adc: Add continuous sampling support

[Zubair Lutfullah :]

On Tue, Sep 17, 2013 at 09:27:27PM -0700, Dmitry Torokhov wrote:
> Hi Zubair,
> 
> On Tue, Sep 17, 2013 at 09:44:07AM +0500, Zubair Lutfullah wrote:
> > +
> > +	ret = devm_request_threaded_irq(indio_dev->dev.parent,
> > +				irq,
> > +				pollfunc_th, pollfunc_bh,
> > +				flags, indio_dev->name,
> > +				indio_dev);
> > +	if (ret)
> > +		goto error_kfifo_free;
> > +
> > +	indio_dev->setup_ops = setup_ops;
> > +	indio_dev->modes |= INDIO_BUFFER_HARDWARE;
> > +
> > +	ret = iio_buffer_register(indio_dev,
> > +				  indio_dev->channels,
> > +				  indio_dev->num_channels);
> > +	if (ret)
> > +		goto error_free_irq;
> > +
> > +	return 0;
> > +
> > +error_free_irq:
> > +	devm_free_irq(indio_dev->dev.parent, irq, indio_dev);
> 
> What is the point of using devm_* here if you are doing explicit
> management of the resource anyway (you explicitly release it in all code
> paths)?
> 
> Thanks.
> 
> -- 
> Dmitry

I admit I am unaware at the moment about how it works.

I use devm and simply ignore the error path?

The devm function header description said something about using
devm_free when freeing. And this is the way I am used to seeing 
error handling.

Zubair

Re: [PATCH 2/2] iio: ti_am335x_adc: Add continuous sampling support

[Jonathan Cameron]

"Zubair Lutfullah :" <zubair.lutfullah@gmail.com> wrote:
>On Tue, Sep 17, 2013 at 09:27:27PM -0700, Dmitry Torokhov wrote:
>> Hi Zubair,
>> 
>> On Tue, Sep 17, 2013 at 09:44:07AM +0500, Zubair Lutfullah wrote:
>> > +
>> > +	ret = devm_request_threaded_irq(indio_dev->dev.parent,
>> > +				irq,
>> > +				pollfunc_th, pollfunc_bh,
>> > +				flags, indio_dev->name,
>> > +				indio_dev);
>> > +	if (ret)
>> > +		goto error_kfifo_free;
>> > +
>> > +	indio_dev->setup_ops = setup_ops;
>> > +	indio_dev->modes |= INDIO_BUFFER_HARDWARE;
>> > +
>> > +	ret = iio_buffer_register(indio_dev,
>> > +				  indio_dev->channels,
>> > +				  indio_dev->num_channels);
>> > +	if (ret)
>> > +		goto error_free_irq;
>> > +
>> > +	return 0;
>> > +
>> > +error_free_irq:
>> > +	devm_free_irq(indio_dev->dev.parent, irq, indio_dev);
>> 
>> What is the point of using devm_* here if you are doing explicit
>> management of the resource anyway (you explicitly release it in all
>code
>> paths)?
>> 
>> Thanks.
>> 
>> -- 
>> Dmitry
>
>I admit I am unaware at the moment about how it works.
>
>I use devm and simply ignore the error path?
>
>The devm function header description said something about using
>devm_free when freeing. And this is the way I am used to seeing 
>error handling.

The devm interfaces ensure this is all cleaned when the device is removed thus avoiding the need to free the stuff explicitly.
Device will get freed on deliberate remove and on an error from probe. Hence you can drop all calls to devm free. The devm free functions are only needed if you wish to free in order to reallocate. This might happen if you want to change a buffer size for instance.
>
>Zubair

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Re: [PATCH 2/2] iio: ti_am335x_adc: Add continuous sampling support

[Zubair Lutfullah :]

On Wed, Sep 18, 2013 at 10:39:42AM +0100, Jonathan Cameron wrote:
> "Zubair Lutfullah :" <zubair.lutfullah@gmail.com> wrote:
> >On Tue, Sep 17, 2013 at 09:27:27PM -0700, Dmitry Torokhov wrote:
> >> Hi Zubair,
> >> 
> >> On Tue, Sep 17, 2013 at 09:44:07AM +0500, Zubair Lutfullah wrote:
> >> > +
> >> > +	ret = devm_request_threaded_irq(indio_dev->dev.parent,
> >> > +				irq,
> >> > +				pollfunc_th, pollfunc_bh,
> >> > +				flags, indio_dev->name,
> >> > +				indio_dev);
> >> > +	if (ret)
> >> > +		goto error_kfifo_free;
...
> >> > +
> >> > +error_free_irq:
> >> > +	devm_free_irq(indio_dev->dev.parent, irq, indio_dev);
> >> 
> >> What is the point of using devm_* here if you are doing explicit
> >> management of the resource anyway (you explicitly release it in all
> >> Dmitry
> 
> The devm interfaces ensure this is all cleaned when the device is removed thus avoiding the need to free the stuff explicitly.
> Device will get freed on deliberate remove and on an error from probe. Hence you can drop all calls to devm free. The devm free functions are only needed if you wish to free in order to reallocate. This might happen if you want to change a buffer size for instance.
>

Thank-you for the feedback.
Updated and resent the series.

Zubair
 
> -- 

Re: [PATCH 2/2] iio: ti_am335x_adc: Add continuous sampling support

[Dmitry Torokhov]

On Wed, Sep 18, 2013 at 10:39:42AM +0100, Jonathan Cameron wrote:
> 
> 
> "Zubair Lutfullah :" <zubair.lutfullah@gmail.com> wrote:
> >On Tue, Sep 17, 2013 at 09:27:27PM -0700, Dmitry Torokhov wrote:
> >> Hi Zubair,
> >> 
> >> On Tue, Sep 17, 2013 at 09:44:07AM +0500, Zubair Lutfullah wrote:
> >> > +
> >> > +	ret = devm_request_threaded_irq(indio_dev->dev.parent,
> >> > +				irq,
> >> > +				pollfunc_th, pollfunc_bh,
> >> > +				flags, indio_dev->name,
> >> > +				indio_dev);
> >> > +	if (ret)
> >> > +		goto error_kfifo_free;
> >> > +
> >> > +	indio_dev->setup_ops = setup_ops;
> >> > +	indio_dev->modes |= INDIO_BUFFER_HARDWARE;
> >> > +
> >> > +	ret = iio_buffer_register(indio_dev,
> >> > +				  indio_dev->channels,
> >> > +				  indio_dev->num_channels);
> >> > +	if (ret)
> >> > +		goto error_free_irq;
> >> > +
> >> > +	return 0;
> >> > +
> >> > +error_free_irq:
> >> > +	devm_free_irq(indio_dev->dev.parent, irq, indio_dev);
> >> 
> >> What is the point of using devm_* here if you are doing explicit
> >> management of the resource anyway (you explicitly release it in all
> >code
> >> paths)?
> >> 
> >> Thanks.
> >> 
> >> -- 
> >> Dmitry
> >
> >I admit I am unaware at the moment about how it works.
> >
> >I use devm and simply ignore the error path?
> >
> >The devm function header description said something about using
> >devm_free when freeing. And this is the way I am used to seeing 
> >error handling.
> 

> The devm interfaces ensure this is all cleaned when the device is
> removed thus avoiding the need to free the stuff explicitly.  Device
> will get freed on deliberate remove and on an error from probe. Hence
> you can drop all calls to devm free. The devm free functions are only
> needed if you wish to free in order to reallocate. This might happen
> if you want to change a buffer size for instance.

However in this case such conversion us dangerous. With all but IRQ
resource managed by the traditional methods they will be released first
with IRQ handler deregistered very last. Therefore if device is not
properly quiesced IRQ raised during driver unbinding is likely to result
in kernel oops.

IOW devm_request_irq() is very often evil (it is still useful if _all_
your resources are managed by devm_*).

In case of your driver I'd recommend switching to
request_irq()/free_irq() instead.

Thanks.

-- 
Dmitry

Re: [PATCH 2/2] iio: ti_am335x_adc: Add continuous sampling support

[Jonathan Cameron]

Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote:
>On Wed, Sep 18, 2013 at 10:39:42AM +0100, Jonathan Cameron wrote:
>> 
>> 
>> "Zubair Lutfullah :" <zubair.lutfullah@gmail.com> wrote:
>> >On Tue, Sep 17, 2013 at 09:27:27PM -0700, Dmitry Torokhov wrote:
>> >> Hi Zubair,
>> >> 
>> >> On Tue, Sep 17, 2013 at 09:44:07AM +0500, Zubair Lutfullah wrote:
>> >> > +
>> >> > +	ret = devm_request_threaded_irq(indio_dev->dev.parent,
>> >> > +				irq,
>> >> > +				pollfunc_th, pollfunc_bh,
>> >> > +				flags, indio_dev->name,
>> >> > +				indio_dev);
>> >> > +	if (ret)
>> >> > +		goto error_kfifo_free;
>> >> > +
>> >> > +	indio_dev->setup_ops = setup_ops;
>> >> > +	indio_dev->modes |= INDIO_BUFFER_HARDWARE;
>> >> > +
>> >> > +	ret = iio_buffer_register(indio_dev,
>> >> > +				  indio_dev->channels,
>> >> > +				  indio_dev->num_channels);
>> >> > +	if (ret)
>> >> > +		goto error_free_irq;
>> >> > +
>> >> > +	return 0;
>> >> > +
>> >> > +error_free_irq:
>> >> > +	devm_free_irq(indio_dev->dev.parent, irq, indio_dev);
>> >> 
>> >> What is the point of using devm_* here if you are doing explicit
>> >> management of the resource anyway (you explicitly release it in
>all
>> >code
>> >> paths)?
>> >> 
>> >> Thanks.
>> >> 
>> >> -- 
>> >> Dmitry
>> >
>> >I admit I am unaware at the moment about how it works.
>> >
>> >I use devm and simply ignore the error path?
>> >
>> >The devm function header description said something about using
>> >devm_free when freeing. And this is the way I am used to seeing 
>> >error handling.
>> 
>
>> The devm interfaces ensure this is all cleaned when the device is
>> removed thus avoiding the need to free the stuff explicitly.  Device
>> will get freed on deliberate remove and on an error from probe. Hence
>> you can drop all calls to devm free. The devm free functions are only
>> needed if you wish to free in order to reallocate. This might happen
>> if you want to change a buffer size for instance.
>
>However in this case such conversion us dangerous. With all but IRQ
>resource managed by the traditional methods they will be released first
>with IRQ handler deregistered very last. Therefore if device is not
>properly quiesced IRQ raised during driver unbinding is likely to
>result
>in kernel oops.
>
>IOW devm_request_irq() is very often evil (it is still useful if _all_
>your resources are managed by devm_*).
>
>In case of your driver I'd recommend switching to
>request_irq()/free_irq() instead.
>
>Thanks.

Pretty much all resources are devm managed in here

https://git.kernel.org/cgit/linux/kernel/git/jic23/iio.git/tree/drivers/iio/adc/ti_am335x_adc.c?h=togreg&id=7a1aeba7ed0d5a1e83fd5a8ee2a2869430d40347

There is a left over calloc which could be converted but that's it.
-- 
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Re: [PATCH 2/2] iio: ti_am335x_adc: Add continuous sampling support

[Dmitry Torokhov]

On Wed, Sep 18, 2013 at 05:12:02PM +0100, Jonathan Cameron wrote:
> 
> 
> Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote:
> >On Wed, Sep 18, 2013 at 10:39:42AM +0100, Jonathan Cameron wrote:
> >> 
> >> 
> >> "Zubair Lutfullah :" <zubair.lutfullah@gmail.com> wrote:
> >> >On Tue, Sep 17, 2013 at 09:27:27PM -0700, Dmitry Torokhov wrote:
> >> >> Hi Zubair,
> >> >> 
> >> >> On Tue, Sep 17, 2013 at 09:44:07AM +0500, Zubair Lutfullah wrote:
> >> >> > +
> >> >> > +	ret = devm_request_threaded_irq(indio_dev->dev.parent,
> >> >> > +				irq,
> >> >> > +				pollfunc_th, pollfunc_bh,
> >> >> > +				flags, indio_dev->name,
> >> >> > +				indio_dev);
> >> >> > +	if (ret)
> >> >> > +		goto error_kfifo_free;
> >> >> > +
> >> >> > +	indio_dev->setup_ops = setup_ops;
> >> >> > +	indio_dev->modes |= INDIO_BUFFER_HARDWARE;
> >> >> > +
> >> >> > +	ret = iio_buffer_register(indio_dev,
> >> >> > +				  indio_dev->channels,
> >> >> > +				  indio_dev->num_channels);
> >> >> > +	if (ret)
> >> >> > +		goto error_free_irq;
> >> >> > +
> >> >> > +	return 0;
> >> >> > +
> >> >> > +error_free_irq:
> >> >> > +	devm_free_irq(indio_dev->dev.parent, irq, indio_dev);
> >> >> 
> >> >> What is the point of using devm_* here if you are doing explicit
> >> >> management of the resource anyway (you explicitly release it in
> >all
> >> >code
> >> >> paths)?
> >> >> 
> >> >> Thanks.
> >> >> 
> >> >> -- 
> >> >> Dmitry
> >> >
> >> >I admit I am unaware at the moment about how it works.
> >> >
> >> >I use devm and simply ignore the error path?
> >> >
> >> >The devm function header description said something about using
> >> >devm_free when freeing. And this is the way I am used to seeing 
> >> >error handling.
> >> 
> >
> >> The devm interfaces ensure this is all cleaned when the device is
> >> removed thus avoiding the need to free the stuff explicitly.  Device
> >> will get freed on deliberate remove and on an error from probe. Hence
> >> you can drop all calls to devm free. The devm free functions are only
> >> needed if you wish to free in order to reallocate. This might happen
> >> if you want to change a buffer size for instance.
> >
> >However in this case such conversion us dangerous. With all but IRQ
> >resource managed by the traditional methods they will be released first
> >with IRQ handler deregistered very last. Therefore if device is not
> >properly quiesced IRQ raised during driver unbinding is likely to
> >result
> >in kernel oops.
> >
> >IOW devm_request_irq() is very often evil (it is still useful if _all_
> >your resources are managed by devm_*).
> >
> >In case of your driver I'd recommend switching to
> >request_irq()/free_irq() instead.
> >
> >Thanks.
> 
> Pretty much all resources are devm managed in here
> 
> https://git.kernel.org/cgit/linux/kernel/git/jic23/iio.git/tree/drivers/iio/adc/ti_am335x_adc.c?h=togreg&id=7a1aeba7ed0d5a1e83fd5a8ee2a2869430d40347


So we are guaranteed that that new kfifo that is being allocated just
before we requesting IRQ and will be freed way before we free the IRQ
will not be used by the IOTQ handler?

Thanks.

-- 
Dmitry

Re: [PATCH 2/2] iio: ti_am335x_adc: Add continuous sampling support

[Jonathan Cameron]

Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote:
>On Wed, Sep 18, 2013 at 05:12:02PM +0100, Jonathan Cameron wrote:
>> 
>> 
>> Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote:
>> >On Wed, Sep 18, 2013 at 10:39:42AM +0100, Jonathan Cameron wrote:
>> >> 
>> >> 
>> >> "Zubair Lutfullah :" <zubair.lutfullah@gmail.com> wrote:
>> >> >On Tue, Sep 17, 2013 at 09:27:27PM -0700, Dmitry Torokhov wrote:
>> >> >> Hi Zubair,
>> >> >> 
>> >> >> On Tue, Sep 17, 2013 at 09:44:07AM +0500, Zubair Lutfullah
>wrote:
>> >> >> > +
>> >> >> > +	ret = devm_request_threaded_irq(indio_dev->dev.parent,
>> >> >> > +				irq,
>> >> >> > +				pollfunc_th, pollfunc_bh,
>> >> >> > +				flags, indio_dev->name,
>> >> >> > +				indio_dev);
>> >> >> > +	if (ret)
>> >> >> > +		goto error_kfifo_free;
>> >> >> > +
>> >> >> > +	indio_dev->setup_ops = setup_ops;
>> >> >> > +	indio_dev->modes |= INDIO_BUFFER_HARDWARE;
>> >> >> > +
>> >> >> > +	ret = iio_buffer_register(indio_dev,
>> >> >> > +				  indio_dev->channels,
>> >> >> > +				  indio_dev->num_channels);
>> >> >> > +	if (ret)
>> >> >> > +		goto error_free_irq;
>> >> >> > +
>> >> >> > +	return 0;
>> >> >> > +
>> >> >> > +error_free_irq:
>> >> >> > +	devm_free_irq(indio_dev->dev.parent, irq, indio_dev);
>> >> >> 
>> >> >> What is the point of using devm_* here if you are doing
>explicit
>> >> >> management of the resource anyway (you explicitly release it in
>> >all
>> >> >code
>> >> >> paths)?
>> >> >> 
>> >> >> Thanks.
>> >> >> 
>> >> >> -- 
>> >> >> Dmitry
>> >> >
>> >> >I admit I am unaware at the moment about how it works.
>> >> >
>> >> >I use devm and simply ignore the error path?
>> >> >
>> >> >The devm function header description said something about using
>> >> >devm_free when freeing. And this is the way I am used to seeing 
>> >> >error handling.
>> >> 
>> >
>> >> The devm interfaces ensure this is all cleaned when the device is
>> >> removed thus avoiding the need to free the stuff explicitly. 
>Device
>> >> will get freed on deliberate remove and on an error from probe.
>Hence
>> >> you can drop all calls to devm free. The devm free functions are
>only
>> >> needed if you wish to free in order to reallocate. This might
>happen
>> >> if you want to change a buffer size for instance.
>> >
>> >However in this case such conversion us dangerous. With all but IRQ
>> >resource managed by the traditional methods they will be released
>first
>> >with IRQ handler deregistered very last. Therefore if device is not
>> >properly quiesced IRQ raised during driver unbinding is likely to
>> >result
>> >in kernel oops.
>> >
>> >IOW devm_request_irq() is very often evil (it is still useful if
>_all_
>> >your resources are managed by devm_*).
>> >
>> >In case of your driver I'd recommend switching to
>> >request_irq()/free_irq() instead.
>> >
>> >Thanks.
>> 
>> Pretty much all resources are devm managed in here
>> 
>>
>https://git.kernel.org/cgit/linux/kernel/git/jic23/iio.git/tree/drivers/iio/adc/ti_am335x_adc.c?h=togreg&id=7a1aeba7ed0d5a1e83fd5a8ee2a2869430d40347
>
>
>So we are guaranteed that that new kfifo that is being allocated just
>before we requesting IRQ and will be freed way before we free the IRQ
>will not be used by the IOTQ handler?
>
>Thanks.
Good point. I forgot about that.  The source of interrupts 'should' be disabled before the kfifo is freed but I guess perhaps better to play it safe. Would take a fair bit of review to be sure that is not going to cause grief.

A few more devm handlers need writing before it is truly useful here.

Thanks for pointing this out.

J

-- 
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Re: [PATCH 2/2] iio: ti_am335x_adc: Add continuous sampling support

[Zubair Lutfullah :]

On Wed, Sep 18, 2013 at 06:05:12PM +0100, Jonathan Cameron wrote:
> 
> >> >However in this case such conversion us dangerous. With all but IRQ
> >> >resource managed by the traditional methods they will be released
> >first
> >> >with IRQ handler deregistered very last. Therefore if device is not
> >> >properly quiesced IRQ raised during driver unbinding is likely to
> >> >result
> >> >in kernel oops.
> >> >
> >> >IOW devm_request_irq() is very often evil (it is still useful if
> >_all_
> >> >your resources are managed by devm_*).
> >> >
> >> >In case of your driver I'd recommend switching to
> >> >request_irq()/free_irq() instead.
> >> >
> >> >Thanks.
> >> 
> >> Pretty much all resources are devm managed in here
> >> 
> >>
> >https://git.kernel.org/cgit/linux/kernel/git/jic23/iio.git/tree/drivers/iio/adc/ti_am335x_adc.c?h=togreg&id=7a1aeba7ed0d5a1e83fd5a8ee2a2869430d40347
> >
> >
> >So we are guaranteed that that new kfifo that is being allocated just
> >before we requesting IRQ and will be freed way before we free the IRQ
> >will not be used by the IOTQ handler?
> >
> >Thanks.
> Good point. I forgot about that.  The source of interrupts 'should' be disabled before the kfifo is freed but I guess perhaps better to play it safe. Would take a fair bit of review to be sure that is not going to cause grief.
> 
> A few more devm handlers need writing before it is truly useful here.
> 
> Thanks for pointing this out.
> 
> J

If I understand the conclusion correctly, no devm here?

Zubair

Re: [PATCH 2/2] iio: ti_am335x_adc: Add continuous sampling support

[Jonathan Cameron]

"Zubair Lutfullah :" <zubair.lutfullah@gmail.com> wrote:
>On Wed, Sep 18, 2013 at 06:05:12PM +0100, Jonathan Cameron wrote:
>> 
>> >> >However in this case such conversion us dangerous. With all but
>IRQ
>> >> >resource managed by the traditional methods they will be released
>> >first
>> >> >with IRQ handler deregistered very last. Therefore if device is
>not
>> >> >properly quiesced IRQ raised during driver unbinding is likely to
>> >> >result
>> >> >in kernel oops.
>> >> >
>> >> >IOW devm_request_irq() is very often evil (it is still useful if
>> >_all_
>> >> >your resources are managed by devm_*).
>> >> >
>> >> >In case of your driver I'd recommend switching to
>> >> >request_irq()/free_irq() instead.
>> >> >
>> >> >Thanks.
>> >> 
>> >> Pretty much all resources are devm managed in here
>> >> 
>> >>
>>
>>https://git.kernel.org/cgit/linux/kernel/git/jic23/iio.git/tree/drivers/iio/adc/ti_am335x_adc.c?h=togreg&id=7a1aeba7ed0d5a1e83fd5a8ee2a2869430d40347
>> >
>> >
>> >So we are guaranteed that that new kfifo that is being allocated
>just
>> >before we requesting IRQ and will be freed way before we free the
>IRQ
>> >will not be used by the IOTQ handler?
>> >
>> >Thanks.
>> Good point. I forgot about that.  The source of interrupts 'should'
>be disabled before the kfifo is freed but I guess perhaps better to
>play it safe. Would take a fair bit of review to be sure that is not
>going to cause grief.
>> 
>> A few more devm handlers need writing before it is truly useful here.
>> 
>> Thanks for pointing this out.
>> 
>> J
>
>If I understand the conclusion correctly, no devm here?

No devm for the irq. The rest are fine.
>
>Zubair
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