[PATCH iwl-net v2 0/4] igc: Fix PTM timeout

[PATCH iwl-net v2 0/4] igc: Fix PTM timeout

[Chris H]

There have been sporadic reports of PTM timeouts using i225/i226 devices

These timeouts have been root caused to:

1) Manipulating the PTM status register while PTM is enabled and triggered
2) The hardware retrying too quickly when an inappropriate response is
   received from the upstream device

The issue can be reproduced with the following:

$ sudo phc2sys -R 1000 -O 0 -i tsn0 -m

Note: 1000 Hz (-R 1000) is unrealistically large, but provides a way to
quickly reproduce the issue.

PHC2SYS exits with:

"ioctl PTP_OFFSET_PRECISE: Connection timed out" when the PTM transaction
  fails

Changelog:

v1 -> v2: -Removed patch modifying PTM retry loop count
      	  -Moved PTM mutex initialization from igc_reset() to igc_ptp_init()
	   called once in igc_probe()


Christopher S M Hall (4):
  igc: Ensure the PTM cycle is reliably triggered
  igc: Lengthen the hardware retry time to prevent timeouts
  igc: Move ktime snapshot into PTM retry loop
  igc: Add lock preventing multiple simultaneous PTM transactions

 drivers/net/ethernet/intel/igc/igc.h         |  1 +
 drivers/net/ethernet/intel/igc/igc_defines.h |  3 +-
 drivers/net/ethernet/intel/igc/igc_ptp.c     | 98 ++++++++++++--------
 3 files changed, 62 insertions(+), 40 deletions(-)

-- 
2.34.1

[PATCH iwl-net v2 1/4] igc: Ensure the PTM cycle is reliably triggered

[Chris H]

From: Christopher S M Hall <christopher.s.hall@intel.com>

Writing to clear the PTM status 'valid' bit while the PTM cycle is
triggered results in unreliable PTM operation. To fix this, clear the
PTM 'trigger' and status after each PTM transaction.

The issue can be reproduced with the following:

$ sudo phc2sys -R 1000 -O 0 -i tsn0 -m

Note: 1000 Hz (-R 1000) is unrealistically large, but provides a way to
quickly reproduce the issue.

PHC2SYS exits with:

"ioctl PTP_OFFSET_PRECISE: Connection timed out" when the PTM transaction
  fails

Fixes: a90ec8483732 ("igc: Add support for PTP getcrosststamp()")
Signed-off-by: Christopher S M Hall <christopher.s.hall@intel.com>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
---
 drivers/net/ethernet/intel/igc/igc_defines.h |  1 +
 drivers/net/ethernet/intel/igc/igc_ptp.c     | 70 ++++++++++++--------
 2 files changed, 42 insertions(+), 29 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_defines.h b/drivers/net/ethernet/intel/igc/igc_defines.h
index 8e449904aa7d..afd0512dc9f8 100644
--- a/drivers/net/ethernet/intel/igc/igc_defines.h
+++ b/drivers/net/ethernet/intel/igc/igc_defines.h
@@ -593,6 +593,7 @@
 #define IGC_PTM_STAT_T4M1_OVFL		BIT(3) /* T4 minus T1 overflow */
 #define IGC_PTM_STAT_ADJUST_1ST		BIT(4) /* 1588 timer adjusted during 1st PTM cycle */
 #define IGC_PTM_STAT_ADJUST_CYC		BIT(5) /* 1588 timer adjusted during non-1st PTM cycle */
+#define IGC_PTM_STAT_ALL        	GENMASK(5, 0) /* Used to clear all status */
 
 /* PCIe PTM Cycle Control */
 #define IGC_PTM_CYCLE_CTRL_CYC_TIME(msec)	((msec) & 0x3ff) /* PTM Cycle Time (msec) */
diff --git a/drivers/net/ethernet/intel/igc/igc_ptp.c b/drivers/net/ethernet/intel/igc/igc_ptp.c
index 946edbad4302..00cc80d8d164 100644
--- a/drivers/net/ethernet/intel/igc/igc_ptp.c
+++ b/drivers/net/ethernet/intel/igc/igc_ptp.c
@@ -974,11 +974,38 @@ static void igc_ptm_log_error(struct igc_adapter *adapter, u32 ptm_stat)
 	}
 }
 
+static void igc_ptm_trigger(struct igc_hw *hw)
+{
+	u32 ctrl;
+
+	/* To "manually" start the PTM cycle we need to set the
+	 * trigger (TRIG) bit
+	 */
+	ctrl = rd32(IGC_PTM_CTRL);
+	ctrl |= IGC_PTM_CTRL_TRIG;
+	wr32(IGC_PTM_CTRL, ctrl);
+	/* Perform flush after write to CTRL register otherwise
+	 * transaction may not start
+	 */
+	wrfl();
+}
+
+static void igc_ptm_reset(struct igc_hw *hw)
+{
+	u32 ctrl;
+
+	ctrl = rd32(IGC_PTM_CTRL);
+	ctrl &= ~IGC_PTM_CTRL_TRIG;
+	wr32(IGC_PTM_CTRL, ctrl);
+	/* Write to clear all status */
+	wr32(IGC_PTM_STAT, IGC_PTM_STAT_ALL);
+}
+
 static int igc_phc_get_syncdevicetime(ktime_t *device,
 				      struct system_counterval_t *system,
 				      void *ctx)
 {
-	u32 stat, t2_curr_h, t2_curr_l, ctrl;
+	u32 stat, t2_curr_h, t2_curr_l;
 	struct igc_adapter *adapter = ctx;
 	struct igc_hw *hw = &adapter->hw;
 	int err, count = 100;
@@ -994,25 +1021,13 @@ static int igc_phc_get_syncdevicetime(ktime_t *device,
 		 * are transitory. Repeating the process returns valid
 		 * data eventually.
 		 */
-
-		/* To "manually" start the PTM cycle we need to clear and
-		 * then set again the TRIG bit.
-		 */
-		ctrl = rd32(IGC_PTM_CTRL);
-		ctrl &= ~IGC_PTM_CTRL_TRIG;
-		wr32(IGC_PTM_CTRL, ctrl);
-		ctrl |= IGC_PTM_CTRL_TRIG;
-		wr32(IGC_PTM_CTRL, ctrl);
-
-		/* The cycle only starts "for real" when software notifies
-		 * that it has read the registers, this is done by setting
-		 * VALID bit.
-		 */
-		wr32(IGC_PTM_STAT, IGC_PTM_STAT_VALID);
+		igc_ptm_trigger(hw);
 
 		err = readx_poll_timeout(rd32, IGC_PTM_STAT, stat,
 					 stat, IGC_PTM_STAT_SLEEP,
 					 IGC_PTM_STAT_TIMEOUT);
+		igc_ptm_reset(hw);
+
 		if (err < 0) {
 			netdev_err(adapter->netdev, "Timeout reading IGC_PTM_STAT register\n");
 			return err;
@@ -1021,15 +1036,7 @@ static int igc_phc_get_syncdevicetime(ktime_t *device,
 		if ((stat & IGC_PTM_STAT_VALID) == IGC_PTM_STAT_VALID)
 			break;
 
-		if (stat & ~IGC_PTM_STAT_VALID) {
-			/* An error occurred, log it. */
-			igc_ptm_log_error(adapter, stat);
-			/* The STAT register is write-1-to-clear (W1C),
-			 * so write the previous error status to clear it.
-			 */
-			wr32(IGC_PTM_STAT, stat);
-			continue;
-		}
+		igc_ptm_log_error(adapter, stat);
 	} while (--count);
 
 	if (!count) {
@@ -1255,7 +1262,7 @@ void igc_ptp_stop(struct igc_adapter *adapter)
 void igc_ptp_reset(struct igc_adapter *adapter)
 {
 	struct igc_hw *hw = &adapter->hw;
-	u32 cycle_ctrl, ctrl;
+	u32 cycle_ctrl, ctrl, stat;
 	unsigned long flags;
 	u32 timadj;
 
@@ -1290,14 +1297,19 @@ void igc_ptp_reset(struct igc_adapter *adapter)
 		ctrl = IGC_PTM_CTRL_EN |
 			IGC_PTM_CTRL_START_NOW |
 			IGC_PTM_CTRL_SHRT_CYC(IGC_PTM_SHORT_CYC_DEFAULT) |
-			IGC_PTM_CTRL_PTM_TO(IGC_PTM_TIMEOUT_DEFAULT) |
-			IGC_PTM_CTRL_TRIG;
+			IGC_PTM_CTRL_PTM_TO(IGC_PTM_TIMEOUT_DEFAULT);
 
 		wr32(IGC_PTM_CTRL, ctrl);
 
 		/* Force the first cycle to run. */
-		wr32(IGC_PTM_STAT, IGC_PTM_STAT_VALID);
+		igc_ptm_trigger(hw);
+
+		if (readx_poll_timeout_atomic(rd32, IGC_PTM_STAT, stat,
+					      stat, IGC_PTM_STAT_SLEEP,
+					      IGC_PTM_STAT_TIMEOUT))
+			netdev_err(adapter->netdev, "Timeout reading IGC_PTM_STAT register\n");
 
+		igc_ptm_reset(hw);
 		break;
 	default:
 		/* No work to do. */
-- 
2.34.1

Re: [PATCH iwl-net v2 1/4] igc: Ensure the PTM cycle is reliably triggered

[Tony Nguyen]

On 10/22/2024 7:30 PM, Chris H wrote:

...

>   static int igc_phc_get_syncdevicetime(ktime_t *device,
>   				      struct system_counterval_t *system,
>   				      void *ctx)
>   {
> -	u32 stat, t2_curr_h, t2_curr_l, ctrl;
> +	u32 stat, t2_curr_h, t2_curr_l;

This needs to move a couple of lines down now for RCT.

Thanks,
Tony

>   	struct igc_adapter *adapter = ctx;
>   	struct igc_hw *hw = &adapter->hw;
>   	int err, count = 100;

Re: [PATCH iwl-net v2 1/4] igc: Ensure the PTM cycle is reliably triggered

[Corinna Vinschen]

Hi Chris,

On Oct 23 02:30, Chris H wrote:
> From: Christopher S M Hall <christopher.s.hall@intel.com>
> 
> Writing to clear the PTM status 'valid' bit while the PTM cycle is
> triggered results in unreliable PTM operation. To fix this, clear the
> PTM 'trigger' and status after each PTM transaction.
> 
> The issue can be reproduced with the following:
> 
> $ sudo phc2sys -R 1000 -O 0 -i tsn0 -m
> 
> Note: 1000 Hz (-R 1000) is unrealistically large, but provides a way to
> quickly reproduce the issue.
> 
> PHC2SYS exits with:
> 
> "ioctl PTP_OFFSET_PRECISE: Connection timed out" when the PTM transaction
>   fails
> 
> Fixes: a90ec8483732 ("igc: Add support for PTP getcrosststamp()")
> Signed-off-by: Christopher S M Hall <christopher.s.hall@intel.com>
> Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>

In the v1 thread in August I asked for adding a description of the kdump
problem we observed to the commit message.  I came up with this text,
maybe we can still add it, or maybe a shhortened version of it?

  This patch also fixes a hang in igc_probe() when loading the igc
  driver in the kdump kernel on systems supporting PTM.

  The igc driver running in the base kernel enables PTM trigger in
  igc_probe().  Therefore the driver is always in PTM trigger mode,
  except in brief periods when manually triggering a PTM cycle.

  When a crash occurs, the NIC is reset while PTM trigger is enabled.
  Due to a hardware problem, the NIC is subsequently in a bad busmaster
  state and doesn't handle register reads/writes.  When running
  igc_probe() in the kdump kernel, the first register access to a NIC
  register hangs driver probing and ultimately breaks kdump.

  With this patch, igc has PTM trigger disabled most of the time,
  and the trigger is only enabled for very brief (10 - 100 us) periods
  when manually triggering a PTM cycle.  Chances that a crash occurs
  during a PTM trigger are not 0, but extremly reduced.


Thanks,
Corinna


> ---
>  drivers/net/ethernet/intel/igc/igc_defines.h |  1 +
>  drivers/net/ethernet/intel/igc/igc_ptp.c     | 70 ++++++++++++--------
>  2 files changed, 42 insertions(+), 29 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/igc/igc_defines.h b/drivers/net/ethernet/intel/igc/igc_defines.h
> index 8e449904aa7d..afd0512dc9f8 100644
> --- a/drivers/net/ethernet/intel/igc/igc_defines.h
> +++ b/drivers/net/ethernet/intel/igc/igc_defines.h
> @@ -593,6 +593,7 @@
>  #define IGC_PTM_STAT_T4M1_OVFL		BIT(3) /* T4 minus T1 overflow */
>  #define IGC_PTM_STAT_ADJUST_1ST		BIT(4) /* 1588 timer adjusted during 1st PTM cycle */
>  #define IGC_PTM_STAT_ADJUST_CYC		BIT(5) /* 1588 timer adjusted during non-1st PTM cycle */
> +#define IGC_PTM_STAT_ALL        	GENMASK(5, 0) /* Used to clear all status */
>  
>  /* PCIe PTM Cycle Control */
>  #define IGC_PTM_CYCLE_CTRL_CYC_TIME(msec)	((msec) & 0x3ff) /* PTM Cycle Time (msec) */
> diff --git a/drivers/net/ethernet/intel/igc/igc_ptp.c b/drivers/net/ethernet/intel/igc/igc_ptp.c
> index 946edbad4302..00cc80d8d164 100644
> --- a/drivers/net/ethernet/intel/igc/igc_ptp.c
> +++ b/drivers/net/ethernet/intel/igc/igc_ptp.c
> @@ -974,11 +974,38 @@ static void igc_ptm_log_error(struct igc_adapter *adapter, u32 ptm_stat)
>  	}
>  }
>  
> +static void igc_ptm_trigger(struct igc_hw *hw)
> +{
> +	u32 ctrl;
> +
> +	/* To "manually" start the PTM cycle we need to set the
> +	 * trigger (TRIG) bit
> +	 */
> +	ctrl = rd32(IGC_PTM_CTRL);
> +	ctrl |= IGC_PTM_CTRL_TRIG;
> +	wr32(IGC_PTM_CTRL, ctrl);
> +	/* Perform flush after write to CTRL register otherwise
> +	 * transaction may not start
> +	 */
> +	wrfl();
> +}
> +
> +static void igc_ptm_reset(struct igc_hw *hw)
> +{
> +	u32 ctrl;
> +
> +	ctrl = rd32(IGC_PTM_CTRL);
> +	ctrl &= ~IGC_PTM_CTRL_TRIG;
> +	wr32(IGC_PTM_CTRL, ctrl);
> +	/* Write to clear all status */
> +	wr32(IGC_PTM_STAT, IGC_PTM_STAT_ALL);
> +}
> +
>  static int igc_phc_get_syncdevicetime(ktime_t *device,
>  				      struct system_counterval_t *system,
>  				      void *ctx)
>  {
> -	u32 stat, t2_curr_h, t2_curr_l, ctrl;
> +	u32 stat, t2_curr_h, t2_curr_l;
>  	struct igc_adapter *adapter = ctx;
>  	struct igc_hw *hw = &adapter->hw;
>  	int err, count = 100;
> @@ -994,25 +1021,13 @@ static int igc_phc_get_syncdevicetime(ktime_t *device,
>  		 * are transitory. Repeating the process returns valid
>  		 * data eventually.
>  		 */
> -
> -		/* To "manually" start the PTM cycle we need to clear and
> -		 * then set again the TRIG bit.
> -		 */
> -		ctrl = rd32(IGC_PTM_CTRL);
> -		ctrl &= ~IGC_PTM_CTRL_TRIG;
> -		wr32(IGC_PTM_CTRL, ctrl);
> -		ctrl |= IGC_PTM_CTRL_TRIG;
> -		wr32(IGC_PTM_CTRL, ctrl);
> -
> -		/* The cycle only starts "for real" when software notifies
> -		 * that it has read the registers, this is done by setting
> -		 * VALID bit.
> -		 */
> -		wr32(IGC_PTM_STAT, IGC_PTM_STAT_VALID);
> +		igc_ptm_trigger(hw);
>  
>  		err = readx_poll_timeout(rd32, IGC_PTM_STAT, stat,
>  					 stat, IGC_PTM_STAT_SLEEP,
>  					 IGC_PTM_STAT_TIMEOUT);
> +		igc_ptm_reset(hw);
> +
>  		if (err < 0) {
>  			netdev_err(adapter->netdev, "Timeout reading IGC_PTM_STAT register\n");
>  			return err;
> @@ -1021,15 +1036,7 @@ static int igc_phc_get_syncdevicetime(ktime_t *device,
>  		if ((stat & IGC_PTM_STAT_VALID) == IGC_PTM_STAT_VALID)
>  			break;
>  
> -		if (stat & ~IGC_PTM_STAT_VALID) {
> -			/* An error occurred, log it. */
> -			igc_ptm_log_error(adapter, stat);
> -			/* The STAT register is write-1-to-clear (W1C),
> -			 * so write the previous error status to clear it.
> -			 */
> -			wr32(IGC_PTM_STAT, stat);
> -			continue;
> -		}
> +		igc_ptm_log_error(adapter, stat);
>  	} while (--count);
>  
>  	if (!count) {
> @@ -1255,7 +1262,7 @@ void igc_ptp_stop(struct igc_adapter *adapter)
>  void igc_ptp_reset(struct igc_adapter *adapter)
>  {
>  	struct igc_hw *hw = &adapter->hw;
> -	u32 cycle_ctrl, ctrl;
> +	u32 cycle_ctrl, ctrl, stat;
>  	unsigned long flags;
>  	u32 timadj;
>  
> @@ -1290,14 +1297,19 @@ void igc_ptp_reset(struct igc_adapter *adapter)
>  		ctrl = IGC_PTM_CTRL_EN |
>  			IGC_PTM_CTRL_START_NOW |
>  			IGC_PTM_CTRL_SHRT_CYC(IGC_PTM_SHORT_CYC_DEFAULT) |
> -			IGC_PTM_CTRL_PTM_TO(IGC_PTM_TIMEOUT_DEFAULT) |
> -			IGC_PTM_CTRL_TRIG;
> +			IGC_PTM_CTRL_PTM_TO(IGC_PTM_TIMEOUT_DEFAULT);
>  
>  		wr32(IGC_PTM_CTRL, ctrl);
>  
>  		/* Force the first cycle to run. */
> -		wr32(IGC_PTM_STAT, IGC_PTM_STAT_VALID);
> +		igc_ptm_trigger(hw);
> +
> +		if (readx_poll_timeout_atomic(rd32, IGC_PTM_STAT, stat,
> +					      stat, IGC_PTM_STAT_SLEEP,
> +					      IGC_PTM_STAT_TIMEOUT))
> +			netdev_err(adapter->netdev, "Timeout reading IGC_PTM_STAT register\n");
>  
> +		igc_ptm_reset(hw);
>  		break;
>  	default:
>  		/* No work to do. */
> -- 
> 2.34.1

Re: [Intel-wired-lan] [PATCH iwl-net v2 1/4] igc: Ensure the PTM cycle is reliably triggered

[Avigail Dahan]

On 23/10/2024 5:30, Chris H wrote:
> From: Christopher S M Hall <christopher.s.hall@intel.com>
> 
> Writing to clear the PTM status 'valid' bit while the PTM cycle is
> triggered results in unreliable PTM operation. To fix this, clear the
> PTM 'trigger' and status after each PTM transaction.
> 
> The issue can be reproduced with the following:
> 
> $ sudo phc2sys -R 1000 -O 0 -i tsn0 -m
> 
> Note: 1000 Hz (-R 1000) is unrealistically large, but provides a way to
> quickly reproduce the issue.
> 
> PHC2SYS exits with:
> 
> "ioctl PTP_OFFSET_PRECISE: Connection timed out" when the PTM transaction
>    fails
> 
> Fixes: a90ec8483732 ("igc: Add support for PTP getcrosststamp()")
> Signed-off-by: Christopher S M Hall <christopher.s.hall@intel.com>
> Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
> ---
>   drivers/net/ethernet/intel/igc/igc_defines.h |  1 +
>   drivers/net/ethernet/intel/igc/igc_ptp.c     | 70 ++++++++++++--------
>   2 files changed, 42 insertions(+), 29 deletions(-)
> 
Tested-by: Avigail Dahan <avigailx.dahan@intel.com>

[PATCH iwl-net v2 2/4] igc: Lengthen the hardware retry time to prevent timeouts

[Chris H]

From: Christopher S M Hall <christopher.s.hall@intel.com>

Lengthen the hardware retry timer to four microseconds.

The i225/i226 hardware retries if it receives an inappropriate response
from the upstream device. If the device retries too quickly, the root
port does not respond.

The issue can be reproduced with the following:

$ sudo phc2sys -R 1000 -O 0 -i tsn0 -m

Note: 1000 Hz (-R 1000) is unrealistically large, but provides a way to
quickly reproduce the issue.

PHC2SYS exits with:

"ioctl PTP_OFFSET_PRECISE: Connection timed out" when the PTM transaction
  fails

Fixes: 6b8aa753a9f9 ("igc: Decrease PTM short interval from 10 us to 1 us")
Signed-off-by: Christopher S M Hall <christopher.s.hall@intel.com>
---
 drivers/net/ethernet/intel/igc/igc_defines.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_defines.h b/drivers/net/ethernet/intel/igc/igc_defines.h
index afd0512dc9f8..58bd9dbbdf43 100644
--- a/drivers/net/ethernet/intel/igc/igc_defines.h
+++ b/drivers/net/ethernet/intel/igc/igc_defines.h
@@ -574,7 +574,7 @@
 #define IGC_PTM_CTRL_SHRT_CYC(usec)	(((usec) & 0x3f) << 2)
 #define IGC_PTM_CTRL_PTM_TO(usec)	(((usec) & 0xff) << 8)
 
-#define IGC_PTM_SHORT_CYC_DEFAULT	1   /* Default short cycle interval */
+#define IGC_PTM_SHORT_CYC_DEFAULT	4   /* Default short cycle interval */
 #define IGC_PTM_CYC_TIME_DEFAULT	5   /* Default PTM cycle time */
 #define IGC_PTM_TIMEOUT_DEFAULT		255 /* Default timeout for PTM errors */
 
-- 
2.34.1

Re: [Intel-wired-lan] [PATCH iwl-net v2 2/4] igc: Lengthen the hardware retry time to prevent timeouts

[Avigail Dahan]

On 23/10/2024 5:30, Chris H wrote:
> From: Christopher S M Hall <christopher.s.hall@intel.com>
> 
> Lengthen the hardware retry timer to four microseconds.
> 
> The i225/i226 hardware retries if it receives an inappropriate response
> from the upstream device. If the device retries too quickly, the root
> port does not respond.
> 
> The issue can be reproduced with the following:
> 
> $ sudo phc2sys -R 1000 -O 0 -i tsn0 -m
> 
> Note: 1000 Hz (-R 1000) is unrealistically large, but provides a way to
> quickly reproduce the issue.
> 
> PHC2SYS exits with:
> 
> "ioctl PTP_OFFSET_PRECISE: Connection timed out" when the PTM transaction
>    fails
> 
> Fixes: 6b8aa753a9f9 ("igc: Decrease PTM short interval from 10 us to 1 us")
> Signed-off-by: Christopher S M Hall <christopher.s.hall@intel.com>
> ---
>   drivers/net/ethernet/intel/igc/igc_defines.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>Tested-by: Avigail Dahan <avigailx.dahan@intel.com>

[PATCH iwl-net v2 3/4] igc: Move ktime snapshot into PTM retry loop

[Chris H]

From: Christopher S M Hall <christopher.s.hall@intel.com>

Move ktime_get_snapshot() into the loop. If a retry does occur, a more
recent snapshot will result in a more accurate cross-timestamp.

Fixes: a90ec8483732 ("igc: Add support for PTP getcrosststamp()")
Signed-off-by: Christopher S M Hall <christopher.s.hall@intel.com>
---
 drivers/net/ethernet/intel/igc/igc_ptp.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_ptp.c b/drivers/net/ethernet/intel/igc/igc_ptp.c
index 00cc80d8d164..fb885fcaa97c 100644
--- a/drivers/net/ethernet/intel/igc/igc_ptp.c
+++ b/drivers/net/ethernet/intel/igc/igc_ptp.c
@@ -1011,16 +1011,16 @@ static int igc_phc_get_syncdevicetime(ktime_t *device,
 	int err, count = 100;
 	ktime_t t1, t2_curr;
 
-	/* Get a snapshot of system clocks to use as historic value. */
-	ktime_get_snapshot(&adapter->snapshot);
-
+	/* Doing this in a loop because in the event of a
+	 * badly timed (ha!) system clock adjustment, we may
+	 * get PTM errors from the PCI root, but these errors
+	 * are transitory. Repeating the process returns valid
+	 * data eventually.
+	 */
 	do {
-		/* Doing this in a loop because in the event of a
-		 * badly timed (ha!) system clock adjustment, we may
-		 * get PTM errors from the PCI root, but these errors
-		 * are transitory. Repeating the process returns valid
-		 * data eventually.
-		 */
+		/* Get a snapshot of system clocks to use as historic value. */
+		ktime_get_snapshot(&adapter->snapshot);
+
 		igc_ptm_trigger(hw);
 
 		err = readx_poll_timeout(rd32, IGC_PTM_STAT, stat,
-- 
2.34.1

Re: [Intel-wired-lan] [PATCH iwl-net v2 3/4] igc: Move ktime snapshot into PTM retry loop

[Mor Bar-Gabay]

On 23/10/2024 5:30, Chris H wrote:
> From: Christopher S M Hall <christopher.s.hall@intel.com>
> 
> Move ktime_get_snapshot() into the loop. If a retry does occur, a more
> recent snapshot will result in a more accurate cross-timestamp.
> 
> Fixes: a90ec8483732 ("igc: Add support for PTP getcrosststamp()")
> Signed-off-by: Christopher S M Hall <christopher.s.hall@intel.com>
> ---
>   drivers/net/ethernet/intel/igc/igc_ptp.c | 18 +++++++++---------
>   1 file changed, 9 insertions(+), 9 deletions(-)
> 
Tested-by: Mor Bar-Gabay <morx.bar.gabay@intel.com>

[PATCH iwl-net v2 4/4] igc: Add lock preventing multiple simultaneous PTM transactions

[Chris H]

From: Christopher S M Hall <christopher.s.hall@intel.com>

Add a mutex around the PTM transaction to prevent multiple transactors

Multiple processes try to initiate a PTM transaction, one or all may
fail. This can be reproduced by running two instances of the
following:

$ sudo phc2sys -O 0 -i tsn0 -m

PHC2SYS exits with:

"ioctl PTP_OFFSET_PRECISE: Connection timed out" when the PTM transaction
 fails

Note: Normally two instance of PHC2SYS will not run, but one process
 should not break another.

Fixes: a90ec8483732 ("igc: Add support for PTP getcrosststamp()")
Signed-off-by: Christopher S M Hall <christopher.s.hall@intel.com>
---
 drivers/net/ethernet/intel/igc/igc.h     |  1 +
 drivers/net/ethernet/intel/igc/igc_ptp.c | 12 ++++++++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
index eac0f966e0e4..323db1e2be38 100644
--- a/drivers/net/ethernet/intel/igc/igc.h
+++ b/drivers/net/ethernet/intel/igc/igc.h
@@ -319,6 +319,7 @@ struct igc_adapter {
 	struct timespec64 prev_ptp_time; /* Pre-reset PTP clock */
 	ktime_t ptp_reset_start; /* Reset time in clock mono */
 	struct system_time_snapshot snapshot;
+	struct mutex ptm_lock; /* Only allow one PTM transaction at a time */
 
 	char fw_version[32];
 
diff --git a/drivers/net/ethernet/intel/igc/igc_ptp.c b/drivers/net/ethernet/intel/igc/igc_ptp.c
index fb885fcaa97c..4e1379b7d2ee 100644
--- a/drivers/net/ethernet/intel/igc/igc_ptp.c
+++ b/drivers/net/ethernet/intel/igc/igc_ptp.c
@@ -1068,9 +1068,16 @@ static int igc_ptp_getcrosststamp(struct ptp_clock_info *ptp,
 {
 	struct igc_adapter *adapter = container_of(ptp, struct igc_adapter,
 						   ptp_caps);
+	int ret;
 
-	return get_device_system_crosststamp(igc_phc_get_syncdevicetime,
-					     adapter, &adapter->snapshot, cts);
+	/* This blocks until any in progress PTM transactions complete */
+	mutex_lock(&adapter->ptm_lock);
+
+	ret = get_device_system_crosststamp(igc_phc_get_syncdevicetime,
+					    adapter, &adapter->snapshot, cts);
+	mutex_unlock(&adapter->ptm_lock);
+
+	return ret;
 }
 
 static int igc_ptp_getcyclesx64(struct ptp_clock_info *ptp,
@@ -1169,6 +1176,7 @@ void igc_ptp_init(struct igc_adapter *adapter)
 	spin_lock_init(&adapter->ptp_tx_lock);
 	spin_lock_init(&adapter->free_timer_lock);
 	spin_lock_init(&adapter->tmreg_lock);
+	mutex_init(&adapter->ptm_lock);
 
 	adapter->tstamp_config.rx_filter = HWTSTAMP_FILTER_NONE;
 	adapter->tstamp_config.tx_type = HWTSTAMP_TX_OFF;
-- 
2.34.1

Re: [PATCH iwl-net v2 4/4] igc: Add lock preventing multiple simultaneous PTM transactions

[Tony Nguyen]

On 10/22/2024 7:30 PM, Chris H wrote:
> From: Christopher S M Hall <christopher.s.hall@intel.com>
> 
> Add a mutex around the PTM transaction to prevent multiple transactors
> 
> Multiple processes try to initiate a PTM transaction, one or all may
> fail. This can be reproduced by running two instances of the
> following:
> 
> $ sudo phc2sys -O 0 -i tsn0 -m
> 
> PHC2SYS exits with:
> 
> "ioctl PTP_OFFSET_PRECISE: Connection timed out" when the PTM transaction
>   fails
> 
> Note: Normally two instance of PHC2SYS will not run, but one process
>   should not break another.
> 
> Fixes: a90ec8483732 ("igc: Add support for PTP getcrosststamp()")
> Signed-off-by: Christopher S M Hall <christopher.s.hall@intel.com>
> ---
>   drivers/net/ethernet/intel/igc/igc.h     |  1 +
>   drivers/net/ethernet/intel/igc/igc_ptp.c | 12 ++++++++++--
>   2 files changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
> index eac0f966e0e4..323db1e2be38 100644
> --- a/drivers/net/ethernet/intel/igc/igc.h
> +++ b/drivers/net/ethernet/intel/igc/igc.h
> @@ -319,6 +319,7 @@ struct igc_adapter {
>   	struct timespec64 prev_ptp_time; /* Pre-reset PTP clock */
>   	ktime_t ptp_reset_start; /* Reset time in clock mono */
>   	struct system_time_snapshot snapshot;
> +	struct mutex ptm_lock; /* Only allow one PTM transaction at a time */
>   
>   	char fw_version[32];
>   
> diff --git a/drivers/net/ethernet/intel/igc/igc_ptp.c b/drivers/net/ethernet/intel/igc/igc_ptp.c
> index fb885fcaa97c..4e1379b7d2ee 100644
> --- a/drivers/net/ethernet/intel/igc/igc_ptp.c
> +++ b/drivers/net/ethernet/intel/igc/igc_ptp.c
> @@ -1068,9 +1068,16 @@ static int igc_ptp_getcrosststamp(struct ptp_clock_info *ptp,
>   {
>   	struct igc_adapter *adapter = container_of(ptp, struct igc_adapter,
>   						   ptp_caps);
> +	int ret;
>   
> -	return get_device_system_crosststamp(igc_phc_get_syncdevicetime,
> -					     adapter, &adapter->snapshot, cts);
> +	/* This blocks until any in progress PTM transactions complete */
> +	mutex_lock(&adapter->ptm_lock);
> +
> +	ret = get_device_system_crosststamp(igc_phc_get_syncdevicetime,
> +					    adapter, &adapter->snapshot, cts);
> +	mutex_unlock(&adapter->ptm_lock);
> +
> +	return ret;
>   }
>   
>   static int igc_ptp_getcyclesx64(struct ptp_clock_info *ptp,
> @@ -1169,6 +1176,7 @@ void igc_ptp_init(struct igc_adapter *adapter)
>   	spin_lock_init(&adapter->ptp_tx_lock);
>   	spin_lock_init(&adapter->free_timer_lock);
>   	spin_lock_init(&adapter->tmreg_lock);
> +	mutex_init(&adapter->ptm_lock);

I believe there should be a corresponding mutex_destroy()?

Thanks,
Tony

>   	adapter->tstamp_config.rx_filter = HWTSTAMP_FILTER_NONE;
>   	adapter->tstamp_config.tx_type = HWTSTAMP_TX_OFF;

Re: [PATCH iwl-net v2 4/4] igc: Add lock preventing multiple simultaneous PTM transactions

[Corinna Vinschen]

Hi Chris,

Same question as in the v1 thread:

On Oct 23 02:30, Chris H wrote:
> From: Christopher S M Hall <christopher.s.hall@intel.com>
> 
> Add a mutex around the PTM transaction to prevent multiple transactors
> 
> Multiple processes try to initiate a PTM transaction, one or all may
> fail. This can be reproduced by running two instances of the
> following:
> 
> $ sudo phc2sys -O 0 -i tsn0 -m
> 
> PHC2SYS exits with:
> 
> "ioctl PTP_OFFSET_PRECISE: Connection timed out" when the PTM transaction
>  fails
> 
> Note: Normally two instance of PHC2SYS will not run, but one process
>  should not break another.
> 
> Fixes: a90ec8483732 ("igc: Add support for PTP getcrosststamp()")
> Signed-off-by: Christopher S M Hall <christopher.s.hall@intel.com>

I saw a former version of the patch which additionally added a mutex
lock/unlock in igc_ptp_reset() just before calling igc_ptm_trigger().
Is it safe to skip that?  igc_ptp_reset() is called from igc_reset()
which in turn is called from quite a few places.


Thanks,
Corinna





> ---
>  drivers/net/ethernet/intel/igc/igc.h     |  1 +
>  drivers/net/ethernet/intel/igc/igc_ptp.c | 12 ++++++++++--
>  2 files changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
> index eac0f966e0e4..323db1e2be38 100644
> --- a/drivers/net/ethernet/intel/igc/igc.h
> +++ b/drivers/net/ethernet/intel/igc/igc.h
> @@ -319,6 +319,7 @@ struct igc_adapter {
>  	struct timespec64 prev_ptp_time; /* Pre-reset PTP clock */
>  	ktime_t ptp_reset_start; /* Reset time in clock mono */
>  	struct system_time_snapshot snapshot;
> +	struct mutex ptm_lock; /* Only allow one PTM transaction at a time */
>  
>  	char fw_version[32];
>  
> diff --git a/drivers/net/ethernet/intel/igc/igc_ptp.c b/drivers/net/ethernet/intel/igc/igc_ptp.c
> index fb885fcaa97c..4e1379b7d2ee 100644
> --- a/drivers/net/ethernet/intel/igc/igc_ptp.c
> +++ b/drivers/net/ethernet/intel/igc/igc_ptp.c
> @@ -1068,9 +1068,16 @@ static int igc_ptp_getcrosststamp(struct ptp_clock_info *ptp,
>  {
>  	struct igc_adapter *adapter = container_of(ptp, struct igc_adapter,
>  						   ptp_caps);
> +	int ret;
>  
> -	return get_device_system_crosststamp(igc_phc_get_syncdevicetime,
> -					     adapter, &adapter->snapshot, cts);
> +	/* This blocks until any in progress PTM transactions complete */
> +	mutex_lock(&adapter->ptm_lock);
> +
> +	ret = get_device_system_crosststamp(igc_phc_get_syncdevicetime,
> +					    adapter, &adapter->snapshot, cts);
> +	mutex_unlock(&adapter->ptm_lock);
> +
> +	return ret;
>  }
>  
>  static int igc_ptp_getcyclesx64(struct ptp_clock_info *ptp,
> @@ -1169,6 +1176,7 @@ void igc_ptp_init(struct igc_adapter *adapter)
>  	spin_lock_init(&adapter->ptp_tx_lock);
>  	spin_lock_init(&adapter->free_timer_lock);
>  	spin_lock_init(&adapter->tmreg_lock);
> +	mutex_init(&adapter->ptm_lock);
>  
>  	adapter->tstamp_config.rx_filter = HWTSTAMP_FILTER_NONE;
>  	adapter->tstamp_config.tx_type = HWTSTAMP_TX_OFF;
> -- 
> 2.34.1

Re: [Intel-wired-lan] [PATCH iwl-net v2 4/4] igc: Add lock preventing multiple simultaneous PTM transactions

[Mor Bar-Gabay]

On 23/10/2024 5:30, Chris H wrote:
> From: Christopher S M Hall <christopher.s.hall@intel.com>
> 
> Add a mutex around the PTM transaction to prevent multiple transactors
> 
> Multiple processes try to initiate a PTM transaction, one or all may
> fail. This can be reproduced by running two instances of the
> following:
> 
> $ sudo phc2sys -O 0 -i tsn0 -m
> 
> PHC2SYS exits with:
> 
> "ioctl PTP_OFFSET_PRECISE: Connection timed out" when the PTM transaction
>   fails
> 
> Note: Normally two instance of PHC2SYS will not run, but one process
>   should not break another.
> 
> Fixes: a90ec8483732 ("igc: Add support for PTP getcrosststamp()")
> Signed-off-by: Christopher S M Hall <christopher.s.hall@intel.com>
> ---
>   drivers/net/ethernet/intel/igc/igc.h     |  1 +
>   drivers/net/ethernet/intel/igc/igc_ptp.c | 12 ++++++++++--
>   2 files changed, 11 insertions(+), 2 deletions(-)
> 
Tested-by: Mor Bar-Gabay <morx.bar.gabay@intel.com>