[PATCH linux dev-4.10] drivers: i2c: fsi: Add proper abort method

[PATCH linux dev-4.10] drivers: i2c: fsi: Add proper abort method

[Eddie James]

From: "Edward A. James" <eajames@us.ibm.com>

Driver wasn't cleaning up on timeout or in an error situation properly.
Need to do a full reset if we fail in order to re-stablish a good state
of the engine.

Signed-off-by: Edward A. James <eajames@us.ibm.com>
---
 drivers/i2c/busses/i2c-fsi.c | 259 +++++++++++++++++++++++++++++++------------
 1 file changed, 191 insertions(+), 68 deletions(-)

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 1af9c01..6c582d8 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -133,6 +133,11 @@
 #define I2C_ESTAT_SELF_BUSY	0x00000040
 #define I2C_ESTAT_VERSION	0x0000001f
 
+#define I2C_PORT_BUSY_RESET	0x80000000
+
+#define I2C_LOCAL_WAIT_TIMEOUT	2		/* jiffies */
+#define I2C_ABORT_TIMEOUT	msecs_to_jiffies(100)
+
 struct fsi_i2c_master {
 	struct fsi_device	*fsi;
 	u8			fifo_size;
@@ -351,22 +356,185 @@ static int fsi_i2c_read_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
 	return rc;
 }
 
+static int fsi_i2c_reset_bus(struct fsi_i2c_master *i2c)
+{
+	int i, rc;
+	u32 mode, dummy = 0;
+
+	rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+	if (rc)
+		return rc;
+
+	mode |= I2C_MODE_DIAG;
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+	if (rc)
+		return rc;
+
+	for (i = 0; i < 9; ++i) {
+		rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
+		if (rc)
+			return rc;
+
+		rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
+		if (rc)
+			return rc;
+	}
+
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
+	if (rc)
+		return rc;
+
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SDA, &dummy);
+	if (rc)
+		return rc;
+
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
+	if (rc)
+		return rc;
+
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SDA, &dummy);
+	if (rc)
+		return rc;
+
+	mode &= ~I2C_MODE_DIAG;
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+
+	return rc;
+}
+
+static int fsi_i2c_reset(struct fsi_i2c_master *i2c, u16 port)
+{
+	int rc;
+	u32 mode, stat, dummy = 0;
+
+	/* reset engine */
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);
+	if (rc)
+		return rc;
+
+	/* re-init engine */
+	rc = fsi_i2c_dev_init(i2c);
+	if (rc)
+		return rc;
+
+	rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+	if (rc)
+		return rc;
+
+	/* set port; default after reset is 0 */
+	if (port) {
+		mode = SETFIELD(I2C_MODE_PORT, mode, port);
+		rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+		if (rc)
+			return rc;
+	}
+
+	/* reset busy register; hw workaround */
+	dummy = I2C_PORT_BUSY_RESET;
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_PORT_BUSY, &dummy);
+	if (rc)
+		return rc;
+
+	/* force bus reset */
+	rc = fsi_i2c_reset_bus(i2c);
+	if (rc)
+		return rc;
+
+	/* reset errors */
+	dummy = 0;
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
+	if (rc)
+		return rc;
+
+	/* wait for command complete */
+	set_current_state(TASK_INTERRUPTIBLE);
+	schedule_timeout(I2C_LOCAL_WAIT_TIMEOUT);
+
+	rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_STAT, &stat);
+	if (rc)
+		return rc;
+
+	if (stat & I2C_STAT_CMD_COMP)
+		return 0;
+
+	/* failed to get command complete; reset engine again */
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);
+	if (rc)
+		return rc;
+
+	/* re-init engine again */
+	rc = fsi_i2c_dev_init(i2c);
+	if (rc)
+		return rc;
+
+	return 0;
+}
+
+static int fsi_i2c_abort(struct fsi_i2c_port *port, u32 status)
+{
+	int rc;
+	unsigned long start;
+	u32 cmd = I2C_CMD_WITH_STOP;
+	struct fsi_device *fsi = port->master->fsi;
+
+	rc = fsi_i2c_reset(port->master, port->port);
+	if (rc)
+		return rc;
+
+	/* skip final stop command for these errors */
+	if (status & (I2C_STAT_PARITY | I2C_STAT_LOST_ARB | I2C_STAT_STOP_ERR))
+		return 0;
+
+	rc = fsi_i2c_write_reg(fsi, I2C_FSI_CMD, &cmd);
+	if (rc)
+		return rc;
+
+	start = jiffies;
+
+	do {
+		rc = fsi_i2c_read_reg(fsi, I2C_FSI_STAT, &status);
+		if (rc)
+			return rc;
+
+		if (status & I2C_STAT_CMD_COMP)
+			return 0;
+
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (schedule_timeout(I2C_LOCAL_WAIT_TIMEOUT) > 0)
+			return -EINTR;
+
+	} while (time_after(start + I2C_ABORT_TIMEOUT, jiffies));
+
+	return -ETIME;
+}
+
 static int fsi_i2c_handle_status(struct fsi_i2c_port *port,
 				 struct i2c_msg *msg, u32 status)
 {
 	int rc;
 	u8 fifo_count;
-	struct fsi_i2c_master *i2c = port->master;
-	u32 dummy = 0;
 
 	if (status & I2C_STAT_ERR) {
-		rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
+		rc = fsi_i2c_abort(port, status);
 		if (rc)
 			return rc;
 
+		if (status & I2C_STAT_INV_CMD)
+			return -EINVAL;
+
+		if (status & (I2C_STAT_PARITY | I2C_STAT_BE_OVERRUN |
+		    I2C_STAT_BE_ACCESS))
+			return -EPROTO;
+
 		if (status & I2C_STAT_NACK)
 			return -EFAULT;
 
+		if (status & I2C_STAT_LOST_ARB)
+			return -ECANCELED;
+
+		if (status & I2C_STAT_STOP_ERR)
+			return -EBADMSG;
+
 		return -EIO;
 	}
 
@@ -396,9 +564,9 @@ static int fsi_i2c_handle_status(struct fsi_i2c_port *port,
 static int fsi_i2c_wait(struct fsi_i2c_port *port, struct i2c_msg *msg,
 			unsigned long timeout)
 {
-	const unsigned long local_timeout = 2; /* jiffies */
 	u32 status = 0;
-	int rc;
+	int rc, rc_abort;
+	unsigned long start = jiffies;
 
 	do {
 		rc = fsi_i2c_read_reg(port->master->fsi, I2C_FSI_STAT,
@@ -419,13 +587,21 @@ static int fsi_i2c_wait(struct fsi_i2c_port *port, struct i2c_msg *msg,
 			continue;
 		}
 
-		set_current_state(TASK_UNINTERRUPTIBLE);
-		schedule_timeout(local_timeout);
-		timeout = (timeout < local_timeout) ? 0 :
-			timeout - local_timeout;
-	} while (timeout);
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (schedule_timeout(I2C_LOCAL_WAIT_TIMEOUT) > 0) {
+			rc = -EINTR;
+			goto abort;
+		}
+	} while (time_after(start + timeout, jiffies));
 
-	return -ETIME;
+	rc = -ETIME;
+
+abort:
+	rc_abort = fsi_i2c_abort(port, status);
+	if (rc_abort)
+		return rc_abort;
+
+	return rc;
 }
 
 static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
@@ -469,72 +645,19 @@ static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
 		| I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA;
 }
 
-static int fsi_i2c_low_level_recover_bus(struct fsi_i2c_master *i2c)
-{
-	int i, rc;
-	u32 mode, dummy = 0;
-
-	rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
-	if (rc)
-		return rc;
-
-	mode |= I2C_MODE_DIAG;
-	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
-	if (rc)
-		return rc;
-
-	for (i = 0; i < 9; ++i) {
-		rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
-		if (rc)
-			return rc;
-
-		rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
-		if (rc)
-			return rc;
-	}
-
-	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
-	if (rc)
-		return rc;
-
-	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SDA, &dummy);
-	if (rc)
-		return rc;
-
-	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
-	if (rc)
-		return rc;
-
-	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SDA, &dummy);
-	if (rc)
-		return rc;
-
-	mode &= ~I2C_MODE_DIAG;
-	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
-
-	return rc;
-}
-
 static int fsi_i2c_recover_bus(struct i2c_adapter *adap)
 {
 	int rc;
-	u32 dummy = 0;
 	struct fsi_i2c_port *port = adap->algo_data;
-	struct fsi_i2c_master *i2c = port->master;
+	struct fsi_i2c_master *master = port->master;
 
-	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);
+	rc = fsi_i2c_lock_master(master, adap->timeout);
 	if (rc)
 		return rc;
 
-	rc = fsi_i2c_dev_init(i2c);
-	if (rc)
-		return rc;
+	rc = fsi_i2c_reset(master, port->port);
 
-	rc = fsi_i2c_low_level_recover_bus(i2c);
-	if (rc)
-		return rc;
-
-	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
+	fsi_i2c_unlock_master(master);
 
 	return rc;
 }
-- 
1.8.3.1

Re: [PATCH linux dev-4.10] drivers: i2c: fsi: Add proper abort method

[Andrew Jeffery]

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On Thu, 2017-10-12 at 15:42 -0500, Eddie James wrote:
> > From: "Edward A. James" <eajames@us.ibm.com>
> 
> Driver wasn't cleaning up on timeout or in an error situation properly.
> Need to do a full reset if we fail in order to re-stablish a good state
> of the engine.

Was there a particular use-case that triggered this behaviour or was this just
found in general use? I feel a bit more context would be helpful here. It's a
fairly sizeable patch and I'm surprised recovery was overlooked initially.

Cheers,

Andrew

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Re: [PATCH linux dev-4.10] drivers: i2c: fsi: Add proper abort method

[Eddie James]

On 10/13/2017 01:18 AM, Andrew Jeffery wrote:
> On Thu, 2017-10-12 at 15:42 -0500, Eddie James wrote:
>>> From: "Edward A. James" <eajames@us.ibm.com>
>>   
>> Driver wasn't cleaning up on timeout or in an error situation properly.
>> Need to do a full reset if we fail in order to re-stablish a good state
>> of the engine.
> Was there a particular use-case that triggered this behaviour or was this just
> found in general use? I feel a bit more context would be helpful here. It's a
> fairly sizeable patch and I'm surprised recovery was overlooked initially.

You'd have to hit either a timeout or some non-NACK error condition in 
order to trigger the problem. Somehow NACK doesn't cause the I2C engine 
to get into a bad state. And timeouts it seems to be somewhat 
intermittent. Probably depends what state the bus is in when the driver 
actually bails out.

Thanks,
Eddie

>
> Cheers,
>
> Andrew

Re: [PATCH linux dev-4.10] drivers: i2c: fsi: Add proper abort method

[Andrew Jeffery]

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On Fri, 2017-10-13 at 10:20 -0500, Eddie James wrote:
> 
> On 10/13/2017 01:18 AM, Andrew Jeffery wrote:
> > On Thu, 2017-10-12 at 15:42 -0500, Eddie James wrote:
> > > > From: "Edward A. James" <eajames@us.ibm.com>
> > > 
> > >   
> > > Driver wasn't cleaning up on timeout or in an error situation properly.
> > > Need to do a full reset if we fail in order to re-stablish a good state
> > > of the engine.
> > 
> > Was there a particular use-case that triggered this behaviour or was this just
> > found in general use? I feel a bit more context would be helpful here. It's a
> > fairly sizeable patch and I'm surprised recovery was overlooked initially.
> 
> You'd have to hit either a timeout or some non-NACK error condition in 
> order to trigger the problem. Somehow NACK doesn't cause the I2C engine 
> to get into a bad state. And timeouts it seems to be somewhat 
> intermittent. Probably depends what state the bus is in when the driver 
> actually bails out.

I asked off-list about finding someone to provide at least a Tested-by
(and I'm hoping for a Reviewed-by) tag, did we get anyone?

Cheers,

Andrew

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Re: [PATCH linux dev-4.10] drivers: i2c: fsi: Add proper abort method

[Andrew Jeffery]

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On Thu, 2017-10-12 at 15:42 -0500, Eddie James wrote:
> From: "Edward A. James" <eajames@us.ibm.com>
> 
> Driver wasn't cleaning up on timeout or in an error situation properly.
> Need to do a full reset if we fail in order to re-stablish a good state
> of the engine.
> 
> Signed-off-by: Edward A. James <eajames@us.ibm.com>
> ---
>  drivers/i2c/busses/i2c-fsi.c | 259 +++++++++++++++++++++++++++++++------------
>  1 file changed, 191 insertions(+), 68 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
> index 1af9c01..6c582d8 100644
> --- a/drivers/i2c/busses/i2c-fsi.c
> +++ b/drivers/i2c/busses/i2c-fsi.c
> @@ -133,6 +133,11 @@
>  #define I2C_ESTAT_SELF_BUSY	0x00000040
>  #define I2C_ESTAT_VERSION	0x0000001f
>  
> +#define I2C_PORT_BUSY_RESET	0x80000000
> +
> +#define I2C_LOCAL_WAIT_TIMEOUT	2		/* jiffies */
> +#define I2C_ABORT_TIMEOUT	msecs_to_jiffies(100)
> +
>  struct fsi_i2c_master {
>  	struct fsi_device	*fsi;
>  	u8			fifo_size;
> @@ -351,22 +356,185 @@ static int fsi_i2c_read_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
>  	return rc;
>  }
>  
> +static int fsi_i2c_reset_bus(struct fsi_i2c_master *i2c)
> +{
> +	int i, rc;
> +	u32 mode, dummy = 0;
> +
> +	rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
> +	if (rc)
> +		return rc;
> +
> +	mode |= I2C_MODE_DIAG;
> +	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
> +	if (rc)
> +		return rc;
> +
> +	for (i = 0; i < 9; ++i) {
> +		rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
> +		if (rc)
> +			return rc;
> +
> +		rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
> +		if (rc)
> +			return rc;
> +	}
> +
> +	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
> +	if (rc)
> +		return rc;
> +
> +	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SDA, &dummy);
> +	if (rc)
> +		return rc;
> +
> +	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
> +	if (rc)
> +		return rc;
> +
> +	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SDA, &dummy);
> +	if (rc)
> +		return rc;
> +
> +	mode &= ~I2C_MODE_DIAG;
> +	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
> +
> +	return rc;
> +}
> +
> +static int fsi_i2c_reset(struct fsi_i2c_master *i2c, u16 port)
> +{
> +	int rc;
> +	u32 mode, stat, dummy = 0;
> +
> +	/* reset engine */
> +	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);
> +	if (rc)
> +		return rc;
> +
> +	/* re-init engine */
> +	rc = fsi_i2c_dev_init(i2c);
> +	if (rc)
> +		return rc;
> +
> +	rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
> +	if (rc)
> +		return rc;
> +
> +	/* set port; default after reset is 0 */
> +	if (port) {
> +		mode = SETFIELD(I2C_MODE_PORT, mode, port);
> +		rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
> +		if (rc)
> +			return rc;
> +	}
> +
> +	/* reset busy register; hw workaround */
> +	dummy = I2C_PORT_BUSY_RESET;
> +	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_PORT_BUSY, &dummy);
> +	if (rc)
> +		return rc;
> +
> +	/* force bus reset */
> +	rc = fsi_i2c_reset_bus(i2c);
> +	if (rc)
> +		return rc;
> +
> +	/* reset errors */
> +	dummy = 0;
> +	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
> +	if (rc)
> +		return rc;
> +
> +	/* wait for command complete */
> +	set_current_state(TASK_INTERRUPTIBLE);
> +	schedule_timeout(I2C_LOCAL_WAIT_TIMEOUT);

Shouldn't we use the uninterruptible state to ensure we get at least
I2C_LOCAL_WAIT_TIMEOUT in the face of signals?

Andrew

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Re: [PATCH linux dev-4.10] drivers: i2c: fsi: Add proper abort method

[Eddie James]

On 10/20/2017 12:15 AM, Andrew Jeffery wrote:
> On Thu, 2017-10-12 at 15:42 -0500, Eddie James wrote:
>> From: "Edward A. James" <eajames@us.ibm.com>
>>   
>> Driver wasn't cleaning up on timeout or in an error situation properly.
>> Need to do a full reset if we fail in order to re-stablish a good state
>> of the engine.
>>   
>> Signed-off-by: Edward A. James <eajames@us.ibm.com>
>> ---
>>   drivers/i2c/busses/i2c-fsi.c | 259 +++++++++++++++++++++++++++++++------------
>>   1 file changed, 191 insertions(+), 68 deletions(-)
>>   
>> diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
>> index 1af9c01..6c582d8 100644
>> --- a/drivers/i2c/busses/i2c-fsi.c
>> +++ b/drivers/i2c/busses/i2c-fsi.c
>> @@ -133,6 +133,11 @@
>>   #define I2C_ESTAT_SELF_BUSY	0x00000040
>>   #define I2C_ESTAT_VERSION	0x0000001f
>>   
>> +#define I2C_PORT_BUSY_RESET	0x80000000
>> +
>> +#define I2C_LOCAL_WAIT_TIMEOUT	2		/* jiffies */
>> +#define I2C_ABORT_TIMEOUT	msecs_to_jiffies(100)
>> +
>>   struct fsi_i2c_master {
>>   	struct fsi_device	*fsi;
>>   	u8			fifo_size;
>> @@ -351,22 +356,185 @@ static int fsi_i2c_read_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
>>   	return rc;
>>   }
>>   
>> +static int fsi_i2c_reset_bus(struct fsi_i2c_master *i2c)
>> +{
>> +	int i, rc;
>> +	u32 mode, dummy = 0;
>> +
>> +	rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
>> +	if (rc)
>> +		return rc;
>> +
>> +	mode |= I2C_MODE_DIAG;
>> +	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
>> +	if (rc)
>> +		return rc;
>> +
>> +	for (i = 0; i < 9; ++i) {
>> +		rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
>> +		if (rc)
>> +			return rc;
>> +
>> +		rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
>> +		if (rc)
>> +			return rc;
>> +	}
>> +
>> +	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
>> +	if (rc)
>> +		return rc;
>> +
>> +	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SDA, &dummy);
>> +	if (rc)
>> +		return rc;
>> +
>> +	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
>> +	if (rc)
>> +		return rc;
>> +
>> +	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SDA, &dummy);
>> +	if (rc)
>> +		return rc;
>> +
>> +	mode &= ~I2C_MODE_DIAG;
>> +	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
>> +
>> +	return rc;
>> +}
>> +
>> +static int fsi_i2c_reset(struct fsi_i2c_master *i2c, u16 port)
>> +{
>> +	int rc;
>> +	u32 mode, stat, dummy = 0;
>> +
>> +	/* reset engine */
>> +	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);
>> +	if (rc)
>> +		return rc;
>> +
>> +	/* re-init engine */
>> +	rc = fsi_i2c_dev_init(i2c);
>> +	if (rc)
>> +		return rc;
>> +
>> +	rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
>> +	if (rc)
>> +		return rc;
>> +
>> +	/* set port; default after reset is 0 */
>> +	if (port) {
>> +		mode = SETFIELD(I2C_MODE_PORT, mode, port);
>> +		rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
>> +		if (rc)
>> +			return rc;
>> +	}
>> +
>> +	/* reset busy register; hw workaround */
>> +	dummy = I2C_PORT_BUSY_RESET;
>> +	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_PORT_BUSY, &dummy);
>> +	if (rc)
>> +		return rc;
>> +
>> +	/* force bus reset */
>> +	rc = fsi_i2c_reset_bus(i2c);
>> +	if (rc)
>> +		return rc;
>> +
>> +	/* reset errors */
>> +	dummy = 0;
>> +	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
>> +	if (rc)
>> +		return rc;
>> +
>> +	/* wait for command complete */
>> +	set_current_state(TASK_INTERRUPTIBLE);
>> +	schedule_timeout(I2C_LOCAL_WAIT_TIMEOUT);
> Shouldn't we use the uninterruptible state to ensure we get at least
> I2C_LOCAL_WAIT_TIMEOUT in the face of signals?

Good point, I'll switch that.

Thanks!
Eddie

>
> Andrew

Re: [PATCH linux dev-4.10] drivers: i2c: fsi: Add proper abort method

[Eddie James]

On 10/19/2017 11:45 PM, Andrew Jeffery wrote:
> On Fri, 2017-10-13 at 10:20 -0500, Eddie James wrote:
>> On 10/13/2017 01:18 AM, Andrew Jeffery wrote:
>>> On Thu, 2017-10-12 at 15:42 -0500, Eddie James wrote:
>>>>> From: "Edward A. James" <eajames@us.ibm.com>
>>>>    
>>>> Driver wasn't cleaning up on timeout or in an error situation properly.
>>>> Need to do a full reset if we fail in order to re-stablish a good state
>>>> of the engine.
>>> Was there a particular use-case that triggered this behaviour or was this just
>>> found in general use? I feel a bit more context would be helpful here. It's a
>>> fairly sizeable patch and I'm surprised recovery was overlooked initially.
>> You'd have to hit either a timeout or some non-NACK error condition in
>> order to trigger the problem. Somehow NACK doesn't cause the I2C engine
>> to get into a bad state. And timeouts it seems to be somewhat
>> intermittent. Probably depends what state the bus is in when the driver
>> actually bails out.
> I asked off-list about finding someone to provide at least a Tested-by
> (and I'm hoping for a Reviewed-by) tag, did we get anyone?

Sivas ran it through the usual suite of power-on and reboot tests, but 
I'm not sure how extensively the i2c path is exercised there. I can ask 
him to add Tested-by when he returns from vacation.

Eddie

>
> Cheers,
>
> Andrew