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* [PATCH 0/4] w1: omap: fix some regressions/bugs (some were introduced in v5.6 but some are older)
@ 2020-05-23 17:32 H. Nikolaus Schaller
  2020-05-23 17:32 ` [PATCH 1/4] w1: omap-hdq: cleanup to add missing newline for some dev_dbg H. Nikolaus Schaller
                   ` (3 more replies)
  0 siblings, 4 replies; 9+ messages in thread
From: H. Nikolaus Schaller @ 2020-05-23 17:32 UTC (permalink / raw)
  To: Evgeniy Polyakov, H. Nikolaus Schaller, Greg Kroah-Hartman,
	YueHaibing, Tony Lindgren
  Cc: linux-kernel, kernel, letux-kernel, linux-omap

This series fixes:
* some dev_dbg are missing an explicit \n
* wrong return value if battery is removed and no hdq response
* problems with resetting interrupt flags too early leading to timeouts and wrong values
* print error if interrupt flags get mixed up


H. Nikolaus Schaller (4):
  w1: omap-hdq: cleanup to add missing newline for some dev_dbg
  w1: omap-hdq: fix return value to be -1 if there is a timeout
  w1: omap-hdq: fix interrupt handling which did show spurious timeouts
  w1: omap-hdq: print dev_err if irq flags are not cleared

 drivers/w1/masters/omap_hdq.c | 82 ++++++++++++++++++++++++-----------
 1 file changed, 56 insertions(+), 26 deletions(-)

-- 
2.26.2


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [PATCH 1/4] w1: omap-hdq: cleanup to add missing newline for some dev_dbg
  2020-05-23 17:32 [PATCH 0/4] w1: omap: fix some regressions/bugs (some were introduced in v5.6 but some are older) H. Nikolaus Schaller
@ 2020-05-23 17:32 ` H. Nikolaus Schaller
  2020-05-23 18:09   ` Tony Lindgren
  2020-05-23 17:32 ` [PATCH 2/4] w1: omap-hdq: fix return value to be -1 if there is a timeout H. Nikolaus Schaller
                   ` (2 subsequent siblings)
  3 siblings, 1 reply; 9+ messages in thread
From: H. Nikolaus Schaller @ 2020-05-23 17:32 UTC (permalink / raw)
  To: Evgeniy Polyakov, H. Nikolaus Schaller, Greg Kroah-Hartman,
	YueHaibing, Tony Lindgren
  Cc: linux-kernel, kernel, letux-kernel, linux-omap, stable

Otherwise it will corrupt the console log during debugging.

Fixes: 7b5362a603a1 ("w1: omap_hdq: Fix some error/debug handling.")
Cc: stable@vger.kernel.org
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
---
 drivers/w1/masters/omap_hdq.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/w1/masters/omap_hdq.c b/drivers/w1/masters/omap_hdq.c
index aa09f85277767a..d363e2a89fdfc4 100644
--- a/drivers/w1/masters/omap_hdq.c
+++ b/drivers/w1/masters/omap_hdq.c
@@ -155,7 +155,7 @@ static int hdq_write_byte(struct hdq_data *hdq_data, u8 val, u8 *status)
 	/* check irqstatus */
 	if (!(*status & OMAP_HDQ_INT_STATUS_TXCOMPLETE)) {
 		dev_dbg(hdq_data->dev, "timeout waiting for"
-			" TXCOMPLETE/RXCOMPLETE, %x", *status);
+			" TXCOMPLETE/RXCOMPLETE, %x\n", *status);
 		ret = -ETIMEDOUT;
 		goto out;
 	}
@@ -166,7 +166,7 @@ static int hdq_write_byte(struct hdq_data *hdq_data, u8 val, u8 *status)
 			OMAP_HDQ_FLAG_CLEAR, &tmp_status);
 	if (ret) {
 		dev_dbg(hdq_data->dev, "timeout waiting GO bit"
-			" return to zero, %x", tmp_status);
+			" return to zero, %x\n", tmp_status);
 	}
 
 out:
@@ -183,7 +183,7 @@ static irqreturn_t hdq_isr(int irq, void *_hdq)
 	spin_lock_irqsave(&hdq_data->hdq_spinlock, irqflags);
 	hdq_data->hdq_irqstatus = hdq_reg_in(hdq_data, OMAP_HDQ_INT_STATUS);
 	spin_unlock_irqrestore(&hdq_data->hdq_spinlock, irqflags);
-	dev_dbg(hdq_data->dev, "hdq_isr: %x", hdq_data->hdq_irqstatus);
+	dev_dbg(hdq_data->dev, "hdq_isr: %x\n", hdq_data->hdq_irqstatus);
 
 	if (hdq_data->hdq_irqstatus &
 		(OMAP_HDQ_INT_STATUS_TXCOMPLETE | OMAP_HDQ_INT_STATUS_RXCOMPLETE
@@ -248,7 +248,7 @@ static int omap_hdq_break(struct hdq_data *hdq_data)
 	tmp_status = hdq_data->hdq_irqstatus;
 	/* check irqstatus */
 	if (!(tmp_status & OMAP_HDQ_INT_STATUS_TIMEOUT)) {
-		dev_dbg(hdq_data->dev, "timeout waiting for TIMEOUT, %x",
+		dev_dbg(hdq_data->dev, "timeout waiting for TIMEOUT, %x\n",
 				tmp_status);
 		ret = -ETIMEDOUT;
 		goto out;
@@ -275,7 +275,7 @@ static int omap_hdq_break(struct hdq_data *hdq_data)
 			&tmp_status);
 	if (ret)
 		dev_dbg(hdq_data->dev, "timeout waiting INIT&GO bits"
-			" return to zero, %x", tmp_status);
+			" return to zero, %x\n", tmp_status);
 
 out:
 	hdq_reset_irqstatus(hdq_data);
-- 
2.26.2


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [PATCH 2/4] w1: omap-hdq: fix return value to be -1 if there is a timeout
  2020-05-23 17:32 [PATCH 0/4] w1: omap: fix some regressions/bugs (some were introduced in v5.6 but some are older) H. Nikolaus Schaller
  2020-05-23 17:32 ` [PATCH 1/4] w1: omap-hdq: cleanup to add missing newline for some dev_dbg H. Nikolaus Schaller
@ 2020-05-23 17:32 ` H. Nikolaus Schaller
  2020-05-23 18:11   ` Tony Lindgren
  2020-05-23 17:32 ` [PATCH 3/4] w1: omap-hdq: fix interrupt handling which did show spurious timeouts H. Nikolaus Schaller
  2020-05-23 17:32 ` [PATCH 4/4] w1: omap-hdq: print dev_err if irq flags are not cleared H. Nikolaus Schaller
  3 siblings, 1 reply; 9+ messages in thread
From: H. Nikolaus Schaller @ 2020-05-23 17:32 UTC (permalink / raw)
  To: Evgeniy Polyakov, H. Nikolaus Schaller, Greg Kroah-Hartman,
	YueHaibing, Tony Lindgren
  Cc: linux-kernel, kernel, letux-kernel, linux-omap, stable

omap_w1_read_byte() should return -1 (or 0xff) in case of
error (e.g. missing battery).

The code accidentially overwrites the variable ret and not val,
which is returned. So it will return the initial value 0 instead
of -1.

Fixes: 27d13da8782a ("w1: omap-hdq: Simplify driver with PM runtime autosuspend")
Cc: stable@vger.kernel.org # v5.6+
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
---
 drivers/w1/masters/omap_hdq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/w1/masters/omap_hdq.c b/drivers/w1/masters/omap_hdq.c
index d363e2a89fdfc4..9f9ec108b189e2 100644
--- a/drivers/w1/masters/omap_hdq.c
+++ b/drivers/w1/masters/omap_hdq.c
@@ -464,7 +464,7 @@ static u8 omap_w1_read_byte(void *_hdq)
 
 	ret = hdq_read_byte(hdq_data, &val);
 	if (ret)
-		ret = -1;
+		val = -1;
 
 	pm_runtime_mark_last_busy(hdq_data->dev);
 	pm_runtime_put_autosuspend(hdq_data->dev);
-- 
2.26.2


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [PATCH 3/4] w1: omap-hdq: fix interrupt handling which did show spurious timeouts
  2020-05-23 17:32 [PATCH 0/4] w1: omap: fix some regressions/bugs (some were introduced in v5.6 but some are older) H. Nikolaus Schaller
  2020-05-23 17:32 ` [PATCH 1/4] w1: omap-hdq: cleanup to add missing newline for some dev_dbg H. Nikolaus Schaller
  2020-05-23 17:32 ` [PATCH 2/4] w1: omap-hdq: fix return value to be -1 if there is a timeout H. Nikolaus Schaller
@ 2020-05-23 17:32 ` H. Nikolaus Schaller
  2020-05-27 16:46   ` Tony Lindgren
  2020-05-23 17:32 ` [PATCH 4/4] w1: omap-hdq: print dev_err if irq flags are not cleared H. Nikolaus Schaller
  3 siblings, 1 reply; 9+ messages in thread
From: H. Nikolaus Schaller @ 2020-05-23 17:32 UTC (permalink / raw)
  To: Evgeniy Polyakov, H. Nikolaus Schaller, Greg Kroah-Hartman,
	YueHaibing, Tony Lindgren
  Cc: linux-kernel, kernel, letux-kernel, linux-omap, stable

Since

commit 27d13da8782a ("w1: omap-hdq: Simplify driver with PM runtime autosuspend")

was applied,

I did see timeouts and wrong values when reading a bq27000 connected
to hdq of the omap3. This occurred mainly after boot but remained and
only sometimes settled down after several reads.

root@letux:~# time cat /sys/class/power_supply/bq27000-battery/uevent
POWER_SUPPLY_NAME=bq27000-battery
POWER_SUPPLY_STATUS=Discharging
POWER_SUPPLY_PRESENT=1
POWER_SUPPLY_VOLTAGE_NOW=0
POWER_SUPPLY_CURRENT_NOW=0
POWER_SUPPLY_CAPACITY=0
POWER_SUPPLY_CAPACITY_LEVEL=Normal
POWER_SUPPLY_TEMP=-2731
POWER_SUPPLY_TIME_TO_EMPTY_NOW=0
POWER_SUPPLY_TIME_TO_EMPTY_AVG=0
POWER_SUPPLY_TIME_TO_FULL_NOW=0
POWER_SUPPLY_TECHNOLOGY=Li-ion
POWER_SUPPLY_CHARGE_FULL=0
POWER_SUPPLY_CHARGE_NOW=0
POWER_SUPPLY_CHARGE_FULL_DESIGN=0
POWER_SUPPLY_CYCLE_COUNT=0
POWER_SUPPLY_ENERGY_NOW=0
POWER_SUPPLY_POWER_AVG=0
POWER_SUPPLY_HEALTH=Good
POWER_SUPPLY_MANUFACTURER=Texas Instruments

real    0m15.761s
user    0m0.001s
sys     0m0.025s
root@letux:~#

Sometimes the effect did disappear after accessing
the device multiple times, speed went up and results
became correct.

All this indicates that some interrupts from the hdq
controller are lost by the driver.

Enabling debugging revealed that there were spurious tx
and rx timeouts, i.e. the driver does not always recognise
interrupts. The main problem is that rx and tx interrupts
share a single variable which was sometimes reset to
0 wiping out other interrupts. And it was overwritten
by a second interrupt, independent of whether the
previous interrupt was already processed or not.

This patch improves interrupt handling to avoid such
races and loss of interrupt flags.

The ideas are:
* only the hdq_isr() sets bits in hdq_status
* it does not reset any bits
* it does wake_up() if any interrupt is pending
* bits are only reset by the read/write/break functions
  if they were waited for
* this makes sure that no interrupts can be lost
* rx/tx/timeout bits are completely decoupled from each
  other (and not reset all after waiting for any of them)
* which bits to reset is now specified by a new parameter
  to hdq_reset_irqstatus()
* hdq_reset_irqstatus() also returns the state before
  resetting so that we can encapsulate the spinlock
* this should now handle the case that the write and read
  are both already finished quickly before the hdq_write_byte()
  ends.
* Or that two interrupts occur in succession before
  they are processed by the driver.
  Old code may have reset all status bits making the next
  hdq_read_byte() timeout.
* the spinlock now always protects changing of bits in function
  hdq_reset_irqstatus() which could become a read-write-modify
  problem if the interrupt handler tries to read-modify-write
  exactly at the same moment
* we add mutex protection also for hdq_write_byte() just to
  be safe to not to disturb a hdq_read_byte() triggered by
  some other thread/process.

This patch was tested on a GTA04 and results in no
boot problems any more. And first read after boot is now ok:

root@letux:~# time cat /sys/class/power_supply/bq27000-battery/uevent
POWER_SUPPLY_NAME=bq27000-battery
POWER_SUPPLY_STATUS=Discharging
POWER_SUPPLY_PRESENT=1
POWER_SUPPLY_VOLTAGE_NOW=3970000
POWER_SUPPLY_CURRENT_NOW=354144
POWER_SUPPLY_CAPACITY=82
POWER_SUPPLY_CAPACITY_LEVEL=Normal
POWER_SUPPLY_TEMP=266
POWER_SUPPLY_TIME_TO_EMPTY_NOW=7680
POWER_SUPPLY_TIME_TO_EMPTY_AVG=7380
POWER_SUPPLY_TECHNOLOGY=Li-ion
POWER_SUPPLY_CHARGE_FULL=934856
POWER_SUPPLY_CHARGE_NOW=763976
POWER_SUPPLY_CHARGE_FULL_DESIGN=1233792
POWER_SUPPLY_CYCLE_COUNT=82
POWER_SUPPLY_ENERGY_NOW=2852840
POWER_SUPPLY_POWER_AVG=1392840
POWER_SUPPLY_HEALTH=Good
POWER_SUPPLY_MANUFACTURER=Texas Instruments

real    0m0.233s
user    0m0.000s
sys     0m0.025s
root@letux:~#

It was also tested with dev_dbg enabled and more
printk that all activities behave correctly, especially
hdq_write_byte(), hdq_read_byte(), omap_hdq_break().

Not tested is omap_w1_triplet().

Fixes: 27d13da8782a ("w1: omap-hdq: Simplify driver with PM runtime autosuspend")
Cc: stable@vger.kernel.org # v5.6+
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
---
 drivers/w1/masters/omap_hdq.c | 62 ++++++++++++++++++++++++-----------
 1 file changed, 42 insertions(+), 20 deletions(-)

diff --git a/drivers/w1/masters/omap_hdq.c b/drivers/w1/masters/omap_hdq.c
index 9f9ec108b189e2..a6484700f3b388 100644
--- a/drivers/w1/masters/omap_hdq.c
+++ b/drivers/w1/masters/omap_hdq.c
@@ -54,10 +54,10 @@ MODULE_PARM_DESC(w1_id, "1-wire id for the slave detection in HDQ mode");
 struct hdq_data {
 	struct device		*dev;
 	void __iomem		*hdq_base;
-	/* lock status update */
+	/* lock read/write/break operations */
 	struct  mutex		hdq_mutex;
+	/* interrupt status and a lock for it */
 	u8			hdq_irqstatus;
-	/* device lock */
 	spinlock_t		hdq_spinlock;
 	/* mode: 0-HDQ 1-W1 */
 	int                     mode;
@@ -120,13 +120,18 @@ static int hdq_wait_for_flag(struct hdq_data *hdq_data, u32 offset,
 }
 
 /* Clear saved irqstatus after using an interrupt */
-static void hdq_reset_irqstatus(struct hdq_data *hdq_data)
+static u8 hdq_reset_irqstatus(struct hdq_data *hdq_data, u8 bits)
 {
 	unsigned long irqflags;
+	u8 status;
 
 	spin_lock_irqsave(&hdq_data->hdq_spinlock, irqflags);
-	hdq_data->hdq_irqstatus = 0;
+	status = hdq_data->hdq_irqstatus;
+	/* this is a read-modify-write */
+	hdq_data->hdq_irqstatus &= ~bits;
 	spin_unlock_irqrestore(&hdq_data->hdq_spinlock, irqflags);
+
+	return status;
 }
 
 /* write out a byte and fill *status with HDQ_INT_STATUS */
@@ -135,6 +140,12 @@ static int hdq_write_byte(struct hdq_data *hdq_data, u8 val, u8 *status)
 	int ret;
 	u8 tmp_status;
 
+	ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
+	if (ret < 0) {
+		ret = -EINTR;
+		goto rtn;
+	}
+
 	*status = 0;
 
 	hdq_reg_out(hdq_data, OMAP_HDQ_TX_DATA, val);
@@ -144,14 +155,15 @@ static int hdq_write_byte(struct hdq_data *hdq_data, u8 val, u8 *status)
 		OMAP_HDQ_CTRL_STATUS_DIR | OMAP_HDQ_CTRL_STATUS_GO);
 	/* wait for the TXCOMPLETE bit */
 	ret = wait_event_timeout(hdq_wait_queue,
-		hdq_data->hdq_irqstatus, OMAP_HDQ_TIMEOUT);
+		(hdq_data->hdq_irqstatus & OMAP_HDQ_INT_STATUS_TXCOMPLETE),
+		OMAP_HDQ_TIMEOUT);
+	*status = hdq_reset_irqstatus(hdq_data, OMAP_HDQ_INT_STATUS_TXCOMPLETE);
 	if (ret == 0) {
 		dev_dbg(hdq_data->dev, "TX wait elapsed\n");
 		ret = -ETIMEDOUT;
 		goto out;
 	}
 
-	*status = hdq_data->hdq_irqstatus;
 	/* check irqstatus */
 	if (!(*status & OMAP_HDQ_INT_STATUS_TXCOMPLETE)) {
 		dev_dbg(hdq_data->dev, "timeout waiting for"
@@ -170,7 +182,8 @@ static int hdq_write_byte(struct hdq_data *hdq_data, u8 val, u8 *status)
 	}
 
 out:
-	hdq_reset_irqstatus(hdq_data);
+	mutex_unlock(&hdq_data->hdq_mutex);
+rtn:
 	return ret;
 }
 
@@ -181,7 +194,7 @@ static irqreturn_t hdq_isr(int irq, void *_hdq)
 	unsigned long irqflags;
 
 	spin_lock_irqsave(&hdq_data->hdq_spinlock, irqflags);
-	hdq_data->hdq_irqstatus = hdq_reg_in(hdq_data, OMAP_HDQ_INT_STATUS);
+	hdq_data->hdq_irqstatus |= hdq_reg_in(hdq_data, OMAP_HDQ_INT_STATUS);
 	spin_unlock_irqrestore(&hdq_data->hdq_spinlock, irqflags);
 	dev_dbg(hdq_data->dev, "hdq_isr: %x\n", hdq_data->hdq_irqstatus);
 
@@ -238,18 +251,19 @@ static int omap_hdq_break(struct hdq_data *hdq_data)
 
 	/* wait for the TIMEOUT bit */
 	ret = wait_event_timeout(hdq_wait_queue,
-		hdq_data->hdq_irqstatus, OMAP_HDQ_TIMEOUT);
+		(hdq_data->hdq_irqstatus & OMAP_HDQ_INT_STATUS_TIMEOUT),
+		OMAP_HDQ_TIMEOUT);
+	tmp_status = hdq_reset_irqstatus(hdq_data, OMAP_HDQ_INT_STATUS_TIMEOUT);
 	if (ret == 0) {
 		dev_dbg(hdq_data->dev, "break wait elapsed\n");
 		ret = -EINTR;
 		goto out;
 	}
 
-	tmp_status = hdq_data->hdq_irqstatus;
 	/* check irqstatus */
 	if (!(tmp_status & OMAP_HDQ_INT_STATUS_TIMEOUT)) {
 		dev_dbg(hdq_data->dev, "timeout waiting for TIMEOUT, %x\n",
-				tmp_status);
+			tmp_status);
 		ret = -ETIMEDOUT;
 		goto out;
 	}
@@ -278,7 +292,6 @@ static int omap_hdq_break(struct hdq_data *hdq_data)
 			" return to zero, %x\n", tmp_status);
 
 out:
-	hdq_reset_irqstatus(hdq_data);
 	mutex_unlock(&hdq_data->hdq_mutex);
 rtn:
 	return ret;
@@ -309,12 +322,15 @@ static int hdq_read_byte(struct hdq_data *hdq_data, u8 *val)
 		 */
 		wait_event_timeout(hdq_wait_queue,
 				   (hdq_data->hdq_irqstatus
-				    & OMAP_HDQ_INT_STATUS_RXCOMPLETE),
+				    & (OMAP_HDQ_INT_STATUS_RXCOMPLETE |
+				       OMAP_HDQ_INT_STATUS_TIMEOUT)),
 				   OMAP_HDQ_TIMEOUT);
-
+		status = hdq_reset_irqstatus(hdq_data,
+					     OMAP_HDQ_INT_STATUS_RXCOMPLETE |
+					     OMAP_HDQ_INT_STATUS_TIMEOUT);
 		hdq_reg_merge(hdq_data, OMAP_HDQ_CTRL_STATUS, 0,
 			OMAP_HDQ_CTRL_STATUS_DIR);
-		status = hdq_data->hdq_irqstatus;
+
 		/* check irqstatus */
 		if (!(status & OMAP_HDQ_INT_STATUS_RXCOMPLETE)) {
 			dev_dbg(hdq_data->dev, "timeout waiting for"
@@ -322,11 +338,12 @@ static int hdq_read_byte(struct hdq_data *hdq_data, u8 *val)
 			ret = -ETIMEDOUT;
 			goto out;
 		}
+	} else { /* interrupt had occurred before hdq_read_byte was called */
+		hdq_reset_irqstatus(hdq_data, OMAP_HDQ_INT_STATUS_RXCOMPLETE);
 	}
 	/* the data is ready. Read it in! */
 	*val = hdq_reg_in(hdq_data, OMAP_HDQ_RX_DATA);
 out:
-	hdq_reset_irqstatus(hdq_data);
 	mutex_unlock(&hdq_data->hdq_mutex);
 rtn:
 	return ret;
@@ -367,15 +384,15 @@ static u8 omap_w1_triplet(void *_hdq, u8 bdir)
 				 (hdq_data->hdq_irqstatus
 				  & OMAP_HDQ_INT_STATUS_RXCOMPLETE),
 				 OMAP_HDQ_TIMEOUT);
+	/* Must clear irqstatus for another RXCOMPLETE interrupt */
+	hdq_reset_irqstatus(hdq_data, OMAP_HDQ_INT_STATUS_RXCOMPLETE);
+
 	if (err == 0) {
 		dev_dbg(hdq_data->dev, "RX wait elapsed\n");
 		goto out;
 	}
 	id_bit = (hdq_reg_in(_hdq, OMAP_HDQ_RX_DATA) & 0x01);
 
-	/* Must clear irqstatus for another RXCOMPLETE interrupt */
-	hdq_reset_irqstatus(hdq_data);
-
 	/* read comp_bit */
 	hdq_reg_merge(_hdq, OMAP_HDQ_CTRL_STATUS,
 		      ctrl | OMAP_HDQ_CTRL_STATUS_DIR, mask);
@@ -383,6 +400,9 @@ static u8 omap_w1_triplet(void *_hdq, u8 bdir)
 				 (hdq_data->hdq_irqstatus
 				  & OMAP_HDQ_INT_STATUS_RXCOMPLETE),
 				 OMAP_HDQ_TIMEOUT);
+	/* Must clear irqstatus for another RXCOMPLETE interrupt */
+	hdq_reset_irqstatus(hdq_data, OMAP_HDQ_INT_STATUS_RXCOMPLETE);
+
 	if (err == 0) {
 		dev_dbg(hdq_data->dev, "RX wait elapsed\n");
 		goto out;
@@ -409,6 +429,9 @@ static u8 omap_w1_triplet(void *_hdq, u8 bdir)
 				 (hdq_data->hdq_irqstatus
 				  & OMAP_HDQ_INT_STATUS_TXCOMPLETE),
 				 OMAP_HDQ_TIMEOUT);
+	/* Must clear irqstatus for another TXCOMPLETE interrupt */
+	hdq_reset_irqstatus(hdq_data, OMAP_HDQ_INT_STATUS_TXCOMPLETE);
+
 	if (err == 0) {
 		dev_dbg(hdq_data->dev, "TX wait elapsed\n");
 		goto out;
@@ -418,7 +441,6 @@ static u8 omap_w1_triplet(void *_hdq, u8 bdir)
 		      OMAP_HDQ_CTRL_STATUS_SINGLE);
 
 out:
-	hdq_reset_irqstatus(hdq_data);
 	mutex_unlock(&hdq_data->hdq_mutex);
 rtn:
 	pm_runtime_mark_last_busy(hdq_data->dev);
-- 
2.26.2


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [PATCH 4/4] w1: omap-hdq: print dev_err if irq flags are not cleared
  2020-05-23 17:32 [PATCH 0/4] w1: omap: fix some regressions/bugs (some were introduced in v5.6 but some are older) H. Nikolaus Schaller
                   ` (2 preceding siblings ...)
  2020-05-23 17:32 ` [PATCH 3/4] w1: omap-hdq: fix interrupt handling which did show spurious timeouts H. Nikolaus Schaller
@ 2020-05-23 17:32 ` H. Nikolaus Schaller
  2020-05-27 16:46   ` Tony Lindgren
  3 siblings, 1 reply; 9+ messages in thread
From: H. Nikolaus Schaller @ 2020-05-23 17:32 UTC (permalink / raw)
  To: Evgeniy Polyakov, H. Nikolaus Schaller, Greg Kroah-Hartman,
	YueHaibing, Tony Lindgren
  Cc: linux-kernel, kernel, letux-kernel, linux-omap

If irq flags are not cleared for certain operations we
print an error message.

Since this should never occur in normal operation, this
patch is an optional safety-net and debugging tool.

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
---
 drivers/w1/masters/omap_hdq.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/w1/masters/omap_hdq.c b/drivers/w1/masters/omap_hdq.c
index a6484700f3b388..bf2ec59c1f9ddc 100644
--- a/drivers/w1/masters/omap_hdq.c
+++ b/drivers/w1/masters/omap_hdq.c
@@ -146,6 +146,10 @@ static int hdq_write_byte(struct hdq_data *hdq_data, u8 val, u8 *status)
 		goto rtn;
 	}
 
+	if (hdq_data->hdq_irqstatus)
+		dev_err(hdq_data->dev, "TX irqstatus not cleared (%02x)\n",
+			hdq_data->hdq_irqstatus);
+
 	*status = 0;
 
 	hdq_reg_out(hdq_data, OMAP_HDQ_TX_DATA, val);
@@ -243,6 +247,10 @@ static int omap_hdq_break(struct hdq_data *hdq_data)
 		goto rtn;
 	}
 
+	if (hdq_data->hdq_irqstatus)
+		dev_err(hdq_data->dev, "break irqstatus not cleared (%02x)\n",
+			hdq_data->hdq_irqstatus);
+
 	/* set the INIT and GO bit */
 	hdq_reg_merge(hdq_data, OMAP_HDQ_CTRL_STATUS,
 		OMAP_HDQ_CTRL_STATUS_INITIALIZATION | OMAP_HDQ_CTRL_STATUS_GO,
-- 
2.26.2


^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: [PATCH 1/4] w1: omap-hdq: cleanup to add missing newline for some dev_dbg
  2020-05-23 17:32 ` [PATCH 1/4] w1: omap-hdq: cleanup to add missing newline for some dev_dbg H. Nikolaus Schaller
@ 2020-05-23 18:09   ` Tony Lindgren
  0 siblings, 0 replies; 9+ messages in thread
From: Tony Lindgren @ 2020-05-23 18:09 UTC (permalink / raw)
  To: H. Nikolaus Schaller
  Cc: Evgeniy Polyakov, Greg Kroah-Hartman, YueHaibing, linux-kernel,
	kernel, letux-kernel, linux-omap, stable

* H. Nikolaus Schaller <hns@goldelico.com> [200523 17:34]:
> Otherwise it will corrupt the console log during debugging.

Acked-by: Tony Lindgren <tony@atomide.com>

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: [PATCH 2/4] w1: omap-hdq: fix return value to be -1 if there is a timeout
  2020-05-23 17:32 ` [PATCH 2/4] w1: omap-hdq: fix return value to be -1 if there is a timeout H. Nikolaus Schaller
@ 2020-05-23 18:11   ` Tony Lindgren
  0 siblings, 0 replies; 9+ messages in thread
From: Tony Lindgren @ 2020-05-23 18:11 UTC (permalink / raw)
  To: H. Nikolaus Schaller
  Cc: Evgeniy Polyakov, Greg Kroah-Hartman, YueHaibing, linux-kernel,
	kernel, letux-kernel, linux-omap, stable

* H. Nikolaus Schaller <hns@goldelico.com> [200523 17:34]:
> The code accidentially overwrites the variable ret and not val,
> which is returned. So it will return the initial value 0 instead
> of -1.

Oops, sorry about causing this. And thanks for catching it:

Acked-by: Tony Lindgren <tony@atomide.com>

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: [PATCH 3/4] w1: omap-hdq: fix interrupt handling which did show spurious timeouts
  2020-05-23 17:32 ` [PATCH 3/4] w1: omap-hdq: fix interrupt handling which did show spurious timeouts H. Nikolaus Schaller
@ 2020-05-27 16:46   ` Tony Lindgren
  0 siblings, 0 replies; 9+ messages in thread
From: Tony Lindgren @ 2020-05-27 16:46 UTC (permalink / raw)
  To: H. Nikolaus Schaller
  Cc: Evgeniy Polyakov, Greg Kroah-Hartman, YueHaibing, linux-kernel,
	kernel, letux-kernel, linux-omap, stable

* H. Nikolaus Schaller <hns@goldelico.com> [200523 17:34]:
> Since
> 
> commit 27d13da8782a ("w1: omap-hdq: Simplify driver with PM runtime autosuspend")
> 
> was applied,
> 
> I did see timeouts and wrong values when reading a bq27000 connected
> to hdq of the omap3. This occurred mainly after boot but remained and
> only sometimes settled down after several reads.
> 
> root@letux:~# time cat /sys/class/power_supply/bq27000-battery/uevent
> POWER_SUPPLY_NAME=bq27000-battery
> POWER_SUPPLY_STATUS=Discharging
> POWER_SUPPLY_PRESENT=1
> POWER_SUPPLY_VOLTAGE_NOW=0
> POWER_SUPPLY_CURRENT_NOW=0
> POWER_SUPPLY_CAPACITY=0
> POWER_SUPPLY_CAPACITY_LEVEL=Normal
> POWER_SUPPLY_TEMP=-2731
> POWER_SUPPLY_TIME_TO_EMPTY_NOW=0
> POWER_SUPPLY_TIME_TO_EMPTY_AVG=0
> POWER_SUPPLY_TIME_TO_FULL_NOW=0
> POWER_SUPPLY_TECHNOLOGY=Li-ion
> POWER_SUPPLY_CHARGE_FULL=0
> POWER_SUPPLY_CHARGE_NOW=0
> POWER_SUPPLY_CHARGE_FULL_DESIGN=0
> POWER_SUPPLY_CYCLE_COUNT=0
> POWER_SUPPLY_ENERGY_NOW=0
> POWER_SUPPLY_POWER_AVG=0
> POWER_SUPPLY_HEALTH=Good
> POWER_SUPPLY_MANUFACTURER=Texas Instruments
> 
> real    0m15.761s
> user    0m0.001s
> sys     0m0.025s
> root@letux:~#
> 
> Sometimes the effect did disappear after accessing
> the device multiple times, speed went up and results
> became correct.
> 
> All this indicates that some interrupts from the hdq
> controller are lost by the driver.
> 
> Enabling debugging revealed that there were spurious tx
> and rx timeouts, i.e. the driver does not always recognise
> interrupts. The main problem is that rx and tx interrupts
> share a single variable which was sometimes reset to
> 0 wiping out other interrupts. And it was overwritten
> by a second interrupt, independent of whether the
> previous interrupt was already processed or not.
> 
> This patch improves interrupt handling to avoid such
> races and loss of interrupt flags.

Good to hear you got it figured out :) Looks OK to me:

Acked-by: Tony Lindgren <tony@atomide.com>

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: [PATCH 4/4] w1: omap-hdq: print dev_err if irq flags are not cleared
  2020-05-23 17:32 ` [PATCH 4/4] w1: omap-hdq: print dev_err if irq flags are not cleared H. Nikolaus Schaller
@ 2020-05-27 16:46   ` Tony Lindgren
  0 siblings, 0 replies; 9+ messages in thread
From: Tony Lindgren @ 2020-05-27 16:46 UTC (permalink / raw)
  To: H. Nikolaus Schaller
  Cc: Evgeniy Polyakov, Greg Kroah-Hartman, YueHaibing, linux-kernel,
	kernel, letux-kernel, linux-omap

* H. Nikolaus Schaller <hns@goldelico.com> [200523 17:34]:
> If irq flags are not cleared for certain operations we
> print an error message.
> 
> Since this should never occur in normal operation, this
> patch is an optional safety-net and debugging tool.

Acked-by: Tony Lindgren <tony@atomide.com>

^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, back to index

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-05-23 17:32 [PATCH 0/4] w1: omap: fix some regressions/bugs (some were introduced in v5.6 but some are older) H. Nikolaus Schaller
2020-05-23 17:32 ` [PATCH 1/4] w1: omap-hdq: cleanup to add missing newline for some dev_dbg H. Nikolaus Schaller
2020-05-23 18:09   ` Tony Lindgren
2020-05-23 17:32 ` [PATCH 2/4] w1: omap-hdq: fix return value to be -1 if there is a timeout H. Nikolaus Schaller
2020-05-23 18:11   ` Tony Lindgren
2020-05-23 17:32 ` [PATCH 3/4] w1: omap-hdq: fix interrupt handling which did show spurious timeouts H. Nikolaus Schaller
2020-05-27 16:46   ` Tony Lindgren
2020-05-23 17:32 ` [PATCH 4/4] w1: omap-hdq: print dev_err if irq flags are not cleared H. Nikolaus Schaller
2020-05-27 16:46   ` Tony Lindgren

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