[PATCH net-next 0/5][pull request] ice: Improve miscellaneous interrupt code

[PATCH net-next 0/5][pull request] ice: Improve miscellaneous interrupt code

[Tony Nguyen]

Jacob Keller says:

This series improves the driver's use of the threaded IRQ and the
communication between ice_misc_intr() and the ice_misc_intr_thread_fn()
which was previously introduced by commit 1229b33973c7 ("ice: Add low
latency Tx timestamp read").

First, a new custom enumerated return value is used instead of a boolean for
ice_ptp_process_ts(). This significantly reduces the cognitive burden when
reviewing the logic for this function, as the expected action is clear from
the return value name.

Second, the unconditional loop in ice_misc_intr_thread_fn() is removed,
replacing it with a write to the Other Interrupt Cause register. This causes
the MAC to trigger the Tx timestamp interrupt again. This makes it possible
to safely use the ice_misc_intr_thread_fn() to handle other tasks beyond
just the Tx timestamps. It is also easier to reason about since the thread
function will exit cleanly if we do something like disable the interrupt and
call synchronize_irq().

Third, refactor the handling for external timestamp events to use the
miscellaneous thread function. This resolves an issue with the external
time stamps getting blocked while processing the periodic work function
task.

Fourth, a simplification of the ice_misc_intr() function to always return
IRQ_WAKE_THREAD, and schedule the ice service task in the
ice_misc_intr_thread_fn() instead.

Finally, the Other Interrupt Cause is kept disabled over the thread function
processing, rather than immediately re-enabled.

Special thanks to Michal Schmidt for the careful review of the series and
pointing out my misunderstandings of the kernel IRQ code. It has been
determined that the race outlined as being fixed in previous series was
actually introduced by this series itself, which I've since corrected.

The following are changes since commit bfd019d10fdabf70f9b01264aea6d6c7595f9226:
  Merge branch 'crypto-splice-net-make-af_alg-handle-sendmsg-msg_splice_pages'
and are available in the git repository at:
  git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/next-queue 100GbE

Jacob Keller (3):
  ice: introduce ICE_TX_TSTAMP_WORK enumeration
  ice: trigger PFINT_OICR_TSYN_TX interrupt instead of polling
  ice: do not re-enable miscellaneous interrupt until thread_fn
    completes

Karol Kolacinski (2):
  ice: handle extts in the miscellaneous interrupt thread
  ice: always return IRQ_WAKE_THREAD in ice_misc_intr()

 drivers/net/ethernet/intel/ice/ice.h      |  7 +++
 drivers/net/ethernet/intel/ice/ice_main.c | 47 +++++++++++------
 drivers/net/ethernet/intel/ice/ice_ptp.c  | 62 ++++++++++++-----------
 drivers/net/ethernet/intel/ice/ice_ptp.h  | 16 ++++--
 4 files changed, 84 insertions(+), 48 deletions(-)

-- 
2.38.1

[PATCH net-next 1/5] ice: handle extts in the miscellaneous interrupt thread

[Tony Nguyen]

From: Karol Kolacinski <karol.kolacinski@intel.com>

The ice_ptp_extts_work() and ice_ptp_periodic_work() functions are both
scheduled on the same kthread worker, pf.ptp.kworker. The
ice_ptp_periodic_work() function sends to the firmware to interact with the
PHY, and must block to wait for responses.

This can cause delay in responding to the PFINT_OICR_TSYN_EVNT interrupt
cause, ultimately resulting in disruption to processing an input signal of
the frequency is high enough. In our testing, even 100 Hz signals get
disrupted.

Fix this by instead processing the signal inside the miscellaneous
interrupt thread prior to handling Tx timestamps.

Use atomic bits in a new pf->misc_thread bitmap in order to safely
communicate which tasks require processing within the
ice_misc_intr_thread_fn(). This ensures the communication of desired tasks
from the ice_misc_intr() are correctly processed without racing even in the
event that the interrupt triggers again before the thread function exits.

Fixes: 172db5f91d5f ("ice: add support for auxiliary input/output pins")
Signed-off-by: Karol Kolacinski <karol.kolacinski@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Arpana Arland <arpanax.arland@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/ice/ice.h      |  7 ++++++
 drivers/net/ethernet/intel/ice/ice_main.c | 29 ++++++++++++++++-------
 drivers/net/ethernet/intel/ice/ice_ptp.c  | 12 +++-------
 drivers/net/ethernet/intel/ice/ice_ptp.h  |  4 ++--
 4 files changed, 33 insertions(+), 19 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice.h b/drivers/net/ethernet/intel/ice/ice.h
index b4bca1d964a9..4ba3d99439a0 100644
--- a/drivers/net/ethernet/intel/ice/ice.h
+++ b/drivers/net/ethernet/intel/ice/ice.h
@@ -508,6 +508,12 @@ enum ice_pf_flags {
 	ICE_PF_FLAGS_NBITS		/* must be last */
 };
 
+enum ice_misc_thread_tasks {
+	ICE_MISC_THREAD_EXTTS_EVENT,
+	ICE_MISC_THREAD_TX_TSTAMP,
+	ICE_MISC_THREAD_NBITS		/* must be last */
+};
+
 struct ice_switchdev_info {
 	struct ice_vsi *control_vsi;
 	struct ice_vsi *uplink_vsi;
@@ -550,6 +556,7 @@ struct ice_pf {
 	DECLARE_BITMAP(features, ICE_F_MAX);
 	DECLARE_BITMAP(state, ICE_STATE_NBITS);
 	DECLARE_BITMAP(flags, ICE_PF_FLAGS_NBITS);
+	DECLARE_BITMAP(misc_thread, ICE_MISC_THREAD_NBITS);
 	unsigned long *avail_txqs;	/* bitmap to track PF Tx queue usage */
 	unsigned long *avail_rxqs;	/* bitmap to track PF Rx queue usage */
 	unsigned long serv_tmr_period;
diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c
index 62e91512aeab..314a42808e39 100644
--- a/drivers/net/ethernet/intel/ice/ice_main.c
+++ b/drivers/net/ethernet/intel/ice/ice_main.c
@@ -3139,20 +3139,28 @@ static irqreturn_t ice_misc_intr(int __always_unused irq, void *data)
 
 	if (oicr & PFINT_OICR_TSYN_TX_M) {
 		ena_mask &= ~PFINT_OICR_TSYN_TX_M;
-		if (!hw->reset_ongoing)
+		if (!hw->reset_ongoing) {
+			set_bit(ICE_MISC_THREAD_TX_TSTAMP, pf->misc_thread);
 			ret = IRQ_WAKE_THREAD;
+		}
 	}
 
 	if (oicr & PFINT_OICR_TSYN_EVNT_M) {
 		u8 tmr_idx = hw->func_caps.ts_func_info.tmr_index_owned;
 		u32 gltsyn_stat = rd32(hw, GLTSYN_STAT(tmr_idx));
 
-		/* Save EVENTs from GTSYN register */
-		pf->ptp.ext_ts_irq |= gltsyn_stat & (GLTSYN_STAT_EVENT0_M |
-						     GLTSYN_STAT_EVENT1_M |
-						     GLTSYN_STAT_EVENT2_M);
 		ena_mask &= ~PFINT_OICR_TSYN_EVNT_M;
-		kthread_queue_work(pf->ptp.kworker, &pf->ptp.extts_work);
+
+		if (hw->func_caps.ts_func_info.src_tmr_owned) {
+			/* Save EVENTs from GLTSYN register */
+			pf->ptp.ext_ts_irq |= gltsyn_stat &
+					      (GLTSYN_STAT_EVENT0_M |
+					       GLTSYN_STAT_EVENT1_M |
+					       GLTSYN_STAT_EVENT2_M);
+
+			set_bit(ICE_MISC_THREAD_EXTTS_EVENT, pf->misc_thread);
+			ret = IRQ_WAKE_THREAD;
+		}
 	}
 
 #define ICE_AUX_CRIT_ERR (PFINT_OICR_PE_CRITERR_M | PFINT_OICR_HMC_ERR_M | PFINT_OICR_PE_PUSH_M)
@@ -3196,8 +3204,13 @@ static irqreturn_t ice_misc_intr_thread_fn(int __always_unused irq, void *data)
 	if (ice_is_reset_in_progress(pf->state))
 		return IRQ_HANDLED;
 
-	while (!ice_ptp_process_ts(pf))
-		usleep_range(50, 100);
+	if (test_and_clear_bit(ICE_MISC_THREAD_EXTTS_EVENT, pf->misc_thread))
+		ice_ptp_extts_event(pf);
+
+	if (test_and_clear_bit(ICE_MISC_THREAD_TX_TSTAMP, pf->misc_thread)) {
+		while (!ice_ptp_process_ts(pf))
+			usleep_range(50, 100);
+	}
 
 	return IRQ_HANDLED;
 }
diff --git a/drivers/net/ethernet/intel/ice/ice_ptp.c b/drivers/net/ethernet/intel/ice/ice_ptp.c
index d4b6c997141d..6f51ebaf1d70 100644
--- a/drivers/net/ethernet/intel/ice/ice_ptp.c
+++ b/drivers/net/ethernet/intel/ice/ice_ptp.c
@@ -1458,15 +1458,11 @@ static int ice_ptp_adjfine(struct ptp_clock_info *info, long scaled_ppm)
 }
 
 /**
- * ice_ptp_extts_work - Workqueue task function
- * @work: external timestamp work structure
- *
- * Service for PTP external clock event
+ * ice_ptp_extts_event - Process PTP external clock event
+ * @pf: Board private structure
  */
-static void ice_ptp_extts_work(struct kthread_work *work)
+void ice_ptp_extts_event(struct ice_pf *pf)
 {
-	struct ice_ptp *ptp = container_of(work, struct ice_ptp, extts_work);
-	struct ice_pf *pf = container_of(ptp, struct ice_pf, ptp);
 	struct ptp_clock_event event;
 	struct ice_hw *hw = &pf->hw;
 	u8 chan, tmr_idx;
@@ -2558,7 +2554,6 @@ void ice_ptp_prepare_for_reset(struct ice_pf *pf)
 	ice_ptp_cfg_timestamp(pf, false);
 
 	kthread_cancel_delayed_work_sync(&ptp->work);
-	kthread_cancel_work_sync(&ptp->extts_work);
 
 	if (test_bit(ICE_PFR_REQ, pf->state))
 		return;
@@ -2656,7 +2651,6 @@ static int ice_ptp_init_work(struct ice_pf *pf, struct ice_ptp *ptp)
 
 	/* Initialize work functions */
 	kthread_init_delayed_work(&ptp->work, ice_ptp_periodic_work);
-	kthread_init_work(&ptp->extts_work, ice_ptp_extts_work);
 
 	/* Allocate a kworker for handling work required for the ports
 	 * connected to the PTP hardware clock.
diff --git a/drivers/net/ethernet/intel/ice/ice_ptp.h b/drivers/net/ethernet/intel/ice/ice_ptp.h
index 9cda2f43e0e5..9f8902c1e743 100644
--- a/drivers/net/ethernet/intel/ice/ice_ptp.h
+++ b/drivers/net/ethernet/intel/ice/ice_ptp.h
@@ -169,7 +169,6 @@ struct ice_ptp_port {
  * struct ice_ptp - data used for integrating with CONFIG_PTP_1588_CLOCK
  * @port: data for the PHY port initialization procedure
  * @work: delayed work function for periodic tasks
- * @extts_work: work function for handling external Tx timestamps
  * @cached_phc_time: a cached copy of the PHC time for timestamp extension
  * @cached_phc_jiffies: jiffies when cached_phc_time was last updated
  * @ext_ts_chan: the external timestamp channel in use
@@ -190,7 +189,6 @@ struct ice_ptp_port {
 struct ice_ptp {
 	struct ice_ptp_port port;
 	struct kthread_delayed_work work;
-	struct kthread_work extts_work;
 	u64 cached_phc_time;
 	unsigned long cached_phc_jiffies;
 	u8 ext_ts_chan;
@@ -256,6 +254,7 @@ int ice_ptp_get_ts_config(struct ice_pf *pf, struct ifreq *ifr);
 void ice_ptp_cfg_timestamp(struct ice_pf *pf, bool ena);
 int ice_get_ptp_clock_index(struct ice_pf *pf);
 
+void ice_ptp_extts_event(struct ice_pf *pf);
 s8 ice_ptp_request_ts(struct ice_ptp_tx *tx, struct sk_buff *skb);
 bool ice_ptp_process_ts(struct ice_pf *pf);
 
@@ -284,6 +283,7 @@ static inline int ice_get_ptp_clock_index(struct ice_pf *pf)
 	return -1;
 }
 
+static inline void ice_ptp_extts_event(struct ice_pf *pf) { }
 static inline s8
 ice_ptp_request_ts(struct ice_ptp_tx *tx, struct sk_buff *skb)
 {
-- 
2.38.1

[PATCH net-next 2/5] ice: always return IRQ_WAKE_THREAD in ice_misc_intr()

[Tony Nguyen]

From: Karol Kolacinski <karol.kolacinski@intel.com>

Refactor the ice_misc_intr() function to always return IRQ_WAKE_THREAD, and
schedule the service task during the soft IRQ thread function instead of at
the end of the hard IRQ handler.

Remove the duplicate call to ice_service_task_schedule() that happened when
we got a PCI exception.

Signed-off-by: Karol Kolacinski <karol.kolacinski@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Arpana Arland <arpanax.arland@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/ice/ice_main.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c
index 314a42808e39..45dab7f62198 100644
--- a/drivers/net/ethernet/intel/ice/ice_main.c
+++ b/drivers/net/ethernet/intel/ice/ice_main.c
@@ -3058,7 +3058,6 @@ static irqreturn_t ice_misc_intr(int __always_unused irq, void *data)
 {
 	struct ice_pf *pf = (struct ice_pf *)data;
 	struct ice_hw *hw = &pf->hw;
-	irqreturn_t ret = IRQ_NONE;
 	struct device *dev;
 	u32 oicr, ena_mask;
 
@@ -3139,10 +3138,8 @@ static irqreturn_t ice_misc_intr(int __always_unused irq, void *data)
 
 	if (oicr & PFINT_OICR_TSYN_TX_M) {
 		ena_mask &= ~PFINT_OICR_TSYN_TX_M;
-		if (!hw->reset_ongoing) {
+		if (!hw->reset_ongoing)
 			set_bit(ICE_MISC_THREAD_TX_TSTAMP, pf->misc_thread);
-			ret = IRQ_WAKE_THREAD;
-		}
 	}
 
 	if (oicr & PFINT_OICR_TSYN_EVNT_M) {
@@ -3159,7 +3156,6 @@ static irqreturn_t ice_misc_intr(int __always_unused irq, void *data)
 					       GLTSYN_STAT_EVENT2_M);
 
 			set_bit(ICE_MISC_THREAD_EXTTS_EVENT, pf->misc_thread);
-			ret = IRQ_WAKE_THREAD;
 		}
 	}
 
@@ -3180,16 +3176,12 @@ static irqreturn_t ice_misc_intr(int __always_unused irq, void *data)
 		if (oicr & (PFINT_OICR_PCI_EXCEPTION_M |
 			    PFINT_OICR_ECC_ERR_M)) {
 			set_bit(ICE_PFR_REQ, pf->state);
-			ice_service_task_schedule(pf);
 		}
 	}
-	if (!ret)
-		ret = IRQ_HANDLED;
 
-	ice_service_task_schedule(pf);
 	ice_irq_dynamic_ena(hw, NULL, NULL);
 
-	return ret;
+	return IRQ_WAKE_THREAD;
 }
 
 /**
@@ -3204,6 +3196,8 @@ static irqreturn_t ice_misc_intr_thread_fn(int __always_unused irq, void *data)
 	if (ice_is_reset_in_progress(pf->state))
 		return IRQ_HANDLED;
 
+	ice_service_task_schedule(pf);
+
 	if (test_and_clear_bit(ICE_MISC_THREAD_EXTTS_EVENT, pf->misc_thread))
 		ice_ptp_extts_event(pf);
 
-- 
2.38.1

[PATCH net-next 3/5] ice: introduce ICE_TX_TSTAMP_WORK enumeration

[Tony Nguyen]

From: Jacob Keller <jacob.e.keller@intel.com>

The ice_ptp_process_ts() function and its various helper functions return a
boolean value indicating whether any work is remaining. This use of a
boolean has grown confusing as we have multiple helpers that pass status
between each other. Readers must be aware of what "true" and "false" mean,
and it is very easy to get their meaning inverted. The names of the
functions are not standard "yes/no" questions, which is the best practice
for boolean returns.

Replace this use of an enumeration with a custom type, enum
ice_tx_tstamp_work. This enumeration clearly indicates whether all work is
done, or if more work is pending.

To aid in readability, factor the actual list iteration and processing out
into ice_ptp_process_tx_tstamp(), making it void. Then call this in
ice_ptp_tx_tstamp() ensuring that we always check the Tracker list at the
end when determining the appropriate return value.

Now the return value is an explicit name instead of the true or false
value. This is easier to follow and makes reading the resulting callers
much simpler.

In addition, this paves the way for future work to allow E822 hardware to
process timestamps for all functions using a single interrupt on the clock
owning PF.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Arpana Arland <arpanax.arland@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/ice/ice_main.c |  2 +-
 drivers/net/ethernet/intel/ice/ice_ptp.c  | 50 ++++++++++++++---------
 drivers/net/ethernet/intel/ice/ice_ptp.h  | 12 +++++-
 3 files changed, 42 insertions(+), 22 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c
index 45dab7f62198..6811e2a3c154 100644
--- a/drivers/net/ethernet/intel/ice/ice_main.c
+++ b/drivers/net/ethernet/intel/ice/ice_main.c
@@ -3202,7 +3202,7 @@ static irqreturn_t ice_misc_intr_thread_fn(int __always_unused irq, void *data)
 		ice_ptp_extts_event(pf);
 
 	if (test_and_clear_bit(ICE_MISC_THREAD_TX_TSTAMP, pf->misc_thread)) {
-		while (!ice_ptp_process_ts(pf))
+		while (ice_ptp_process_ts(pf) == ICE_TX_TSTAMP_WORK_PENDING)
 			usleep_range(50, 100);
 	}
 
diff --git a/drivers/net/ethernet/intel/ice/ice_ptp.c b/drivers/net/ethernet/intel/ice/ice_ptp.c
index 6f51ebaf1d70..81d96a40d5a7 100644
--- a/drivers/net/ethernet/intel/ice/ice_ptp.c
+++ b/drivers/net/ethernet/intel/ice/ice_ptp.c
@@ -617,7 +617,7 @@ ice_ptp_is_tx_tracker_up(struct ice_ptp_tx *tx)
 }
 
 /**
- * ice_ptp_tx_tstamp - Process Tx timestamps for a port
+ * ice_ptp_process_tx_tstamp - Process Tx timestamps for a port
  * @tx: the PTP Tx timestamp tracker
  *
  * Process timestamps captured by the PHY associated with this port. To do
@@ -633,15 +633,6 @@ ice_ptp_is_tx_tracker_up(struct ice_ptp_tx *tx)
  * 6) extend the 40 bit timestamp value to get a 64 bit timestamp value
  * 7) send this 64 bit timestamp to the stack
  *
- * Returns true if all timestamps were handled, and false if any slots remain
- * without a timestamp.
- *
- * After looping, if we still have waiting SKBs, return false. This may cause
- * us effectively poll even when not strictly necessary. We do this because
- * it's possible a new timestamp was requested around the same time as the
- * interrupt. In some cases hardware might not interrupt us again when the
- * timestamp is captured.
- *
  * Note that we do not hold the tracking lock while reading the Tx timestamp.
  * This is because reading the timestamp requires taking a mutex that might
  * sleep.
@@ -673,10 +664,9 @@ ice_ptp_is_tx_tracker_up(struct ice_ptp_tx *tx)
  * the packet will never be sent by hardware and discard it without reading
  * the timestamp register.
  */
-static bool ice_ptp_tx_tstamp(struct ice_ptp_tx *tx)
+static void ice_ptp_process_tx_tstamp(struct ice_ptp_tx *tx)
 {
 	struct ice_ptp_port *ptp_port;
-	bool more_timestamps;
 	struct ice_pf *pf;
 	struct ice_hw *hw;
 	u64 tstamp_ready;
@@ -685,7 +675,7 @@ static bool ice_ptp_tx_tstamp(struct ice_ptp_tx *tx)
 	u8 idx;
 
 	if (!tx->init)
-		return true;
+		return;
 
 	ptp_port = container_of(tx, struct ice_ptp_port, tx);
 	pf = ptp_port_to_pf(ptp_port);
@@ -694,7 +684,7 @@ static bool ice_ptp_tx_tstamp(struct ice_ptp_tx *tx)
 	/* Read the Tx ready status first */
 	err = ice_get_phy_tx_tstamp_ready(hw, tx->block, &tstamp_ready);
 	if (err)
-		return false;
+		return;
 
 	/* Drop packets if the link went down */
 	link_up = ptp_port->link_up;
@@ -782,15 +772,34 @@ static bool ice_ptp_tx_tstamp(struct ice_ptp_tx *tx)
 		skb_tstamp_tx(skb, &shhwtstamps);
 		dev_kfree_skb_any(skb);
 	}
+}
 
-	/* Check if we still have work to do. If so, re-queue this task to
-	 * poll for remaining timestamps.
-	 */
+/**
+ * ice_ptp_tx_tstamp - Process Tx timestamps for this function.
+ * @tx: Tx tracking structure to initialize
+ *
+ * Returns: ICE_TX_TSTAMP_WORK_PENDING if there are any outstanding incomplete
+ * Tx timestamps, or ICE_TX_TSTAMP_WORK_DONE otherwise.
+ */
+static enum ice_tx_tstamp_work ice_ptp_tx_tstamp(struct ice_ptp_tx *tx)
+{
+	bool more_timestamps;
+
+	if (!tx->init)
+		return ICE_TX_TSTAMP_WORK_DONE;
+
+	/* Process the Tx timestamp tracker */
+	ice_ptp_process_tx_tstamp(tx);
+
+	/* Check if there are outstanding Tx timestamps */
 	spin_lock(&tx->lock);
 	more_timestamps = tx->init && !bitmap_empty(tx->in_use, tx->len);
 	spin_unlock(&tx->lock);
 
-	return !more_timestamps;
+	if (more_timestamps)
+		return ICE_TX_TSTAMP_WORK_PENDING;
+
+	return ICE_TX_TSTAMP_WORK_DONE;
 }
 
 /**
@@ -2426,9 +2435,10 @@ s8 ice_ptp_request_ts(struct ice_ptp_tx *tx, struct sk_buff *skb)
  * ice_ptp_process_ts - Process the PTP Tx timestamps
  * @pf: Board private structure
  *
- * Returns true if timestamps are processed.
+ * Returns: ICE_TX_TSTAMP_WORK_PENDING if there are any outstanding Tx
+ * timestamps that need processing, and ICE_TX_TSTAMP_WORK_DONE otherwise.
  */
-bool ice_ptp_process_ts(struct ice_pf *pf)
+enum ice_tx_tstamp_work ice_ptp_process_ts(struct ice_pf *pf)
 {
 	return ice_ptp_tx_tstamp(&pf->ptp.port.tx);
 }
diff --git a/drivers/net/ethernet/intel/ice/ice_ptp.h b/drivers/net/ethernet/intel/ice/ice_ptp.h
index 9f8902c1e743..995a57019ba7 100644
--- a/drivers/net/ethernet/intel/ice/ice_ptp.h
+++ b/drivers/net/ethernet/intel/ice/ice_ptp.h
@@ -108,6 +108,16 @@ struct ice_tx_tstamp {
 	u64 cached_tstamp;
 };
 
+/**
+ * enum ice_tx_tstamp_work - Status of Tx timestamp work function
+ * @ICE_TX_TSTAMP_WORK_DONE: Tx timestamp processing is complete
+ * @ICE_TX_TSTAMP_WORK_PENDING: More Tx timestamps are pending
+ */
+enum ice_tx_tstamp_work {
+	ICE_TX_TSTAMP_WORK_DONE = 0,
+	ICE_TX_TSTAMP_WORK_PENDING,
+};
+
 /**
  * struct ice_ptp_tx - Tracking structure for all Tx timestamp requests on a port
  * @lock: lock to prevent concurrent access to fields of this struct
@@ -256,7 +266,7 @@ int ice_get_ptp_clock_index(struct ice_pf *pf);
 
 void ice_ptp_extts_event(struct ice_pf *pf);
 s8 ice_ptp_request_ts(struct ice_ptp_tx *tx, struct sk_buff *skb);
-bool ice_ptp_process_ts(struct ice_pf *pf);
+enum ice_tx_tstamp_work ice_ptp_process_ts(struct ice_pf *pf);
 
 void
 ice_ptp_rx_hwtstamp(struct ice_rx_ring *rx_ring,
-- 
2.38.1

[PATCH net-next 4/5] ice: trigger PFINT_OICR_TSYN_TX interrupt instead of polling

[Tony Nguyen]

From: Jacob Keller <jacob.e.keller@intel.com>

In ice_misc_intr_thread_fn(), if we do not complete all Tx timestamp work,
the thread function will poll continuously forever.

For E822 hardware, this wastes time as the return value from
ice_ptp_process_ts() is accurate and always reports correctly that the PHY
actually has new timestamp data.

In addition, if we receive enough timestamps with the right pacing, we may
never exit this polling. Should this occur, other tasks handled by the
ice_misc_intr_thread_fn() will never be processed.

Fix this by instead writing to PFINT_OICR, causing an emulated interrupt to
be triggered immediately. This does take slightly more processing than just
re-checking the timestamps. However, it allows all of the other interrupt
causes a chance to be processed first in the hard IRQ function.

Note that the OICR interrupt is configured to be throttled  to no more than
once every 124 microseconds. This gives an effective interrupt rate of
~8000 interrupts per second. This should thus not cause a significant
increase in overall CPU usage when compared to sleeping.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Arpana Arland <arpanax.arland@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/ice/ice_main.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c
index 6811e2a3c154..2665f72b5461 100644
--- a/drivers/net/ethernet/intel/ice/ice_main.c
+++ b/drivers/net/ethernet/intel/ice/ice_main.c
@@ -3202,8 +3202,15 @@ static irqreturn_t ice_misc_intr_thread_fn(int __always_unused irq, void *data)
 		ice_ptp_extts_event(pf);
 
 	if (test_and_clear_bit(ICE_MISC_THREAD_TX_TSTAMP, pf->misc_thread)) {
-		while (ice_ptp_process_ts(pf) == ICE_TX_TSTAMP_WORK_PENDING)
-			usleep_range(50, 100);
+		struct ice_hw *hw = &pf->hw;
+
+		/* Process outstanding Tx timestamps. If there is more work,
+		 * re-arm the interrupt to trigger again.
+		 */
+		if (ice_ptp_process_ts(pf) == ICE_TX_TSTAMP_WORK_PENDING) {
+			wr32(hw, PFINT_OICR, PFINT_OICR_TSYN_TX_M);
+			ice_flush(hw);
+		}
 	}
 
 	return IRQ_HANDLED;
-- 
2.38.1

[PATCH net-next 5/5] ice: do not re-enable miscellaneous interrupt until thread_fn completes

[Tony Nguyen]

From: Jacob Keller <jacob.e.keller@intel.com>

The ice driver uses threaded IRQ for managing Tx timestamps via the
devm_request_threaded_irq() interface. The ice_misc_intr() handler function
is responsible for processing the hard interrupt context, and can wake the
ice_misc_intr_thread_fn() by returning IRQ_WAKE_THREAD.

The request_threaded_irq() function comment says:

  @handler is still called in hard interrupt context and has to check
  whether the interrupt originates from the device. If yes, it needs to
  disable the interrupt on the device and return IRQ_WAKE_THREAD which will
  wake up the handler thread and run the @thread_fn.

We currently re-enable the Other Interrupt Cause Register (OCIR) at the end of
ice_misc_intr(). In practice, this seems to be ok, but it can make
communicating between the handler function and the thread function
difficult. This is because the interrupt can trigger again while the thread
function is still processing.

Move the OICR update to the end of the thread function, leaving the other
interrupt cause disabled in hardware until we complete one pass of the
thread function. This prevents the miscellaneous interrupt from firing
until after we finish the thread function.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Arpana Arland <arpanax.arland@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/ice/ice_main.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c
index 2665f72b5461..aa57d26a0ac7 100644
--- a/drivers/net/ethernet/intel/ice/ice_main.c
+++ b/drivers/net/ethernet/intel/ice/ice_main.c
@@ -3179,8 +3179,6 @@ static irqreturn_t ice_misc_intr(int __always_unused irq, void *data)
 		}
 	}
 
-	ice_irq_dynamic_ena(hw, NULL, NULL);
-
 	return IRQ_WAKE_THREAD;
 }
 
@@ -3192,6 +3190,9 @@ static irqreturn_t ice_misc_intr(int __always_unused irq, void *data)
 static irqreturn_t ice_misc_intr_thread_fn(int __always_unused irq, void *data)
 {
 	struct ice_pf *pf = data;
+	struct ice_hw *hw;
+
+	hw = &pf->hw;
 
 	if (ice_is_reset_in_progress(pf->state))
 		return IRQ_HANDLED;
@@ -3202,8 +3203,6 @@ static irqreturn_t ice_misc_intr_thread_fn(int __always_unused irq, void *data)
 		ice_ptp_extts_event(pf);
 
 	if (test_and_clear_bit(ICE_MISC_THREAD_TX_TSTAMP, pf->misc_thread)) {
-		struct ice_hw *hw = &pf->hw;
-
 		/* Process outstanding Tx timestamps. If there is more work,
 		 * re-arm the interrupt to trigger again.
 		 */
@@ -3213,6 +3212,8 @@ static irqreturn_t ice_misc_intr_thread_fn(int __always_unused irq, void *data)
 		}
 	}
 
+	ice_irq_dynamic_ena(hw, NULL, NULL);
+
 	return IRQ_HANDLED;
 }
 
-- 
2.38.1

Re: [PATCH net-next 0/5][pull request] ice: Improve miscellaneous interrupt code

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Tony Nguyen <anthony.l.nguyen@intel.com>:

On Thu,  8 Jun 2023 13:21:10 -0700 you wrote:
> Jacob Keller says:
> 
> This series improves the driver's use of the threaded IRQ and the
> communication between ice_misc_intr() and the ice_misc_intr_thread_fn()
> which was previously introduced by commit 1229b33973c7 ("ice: Add low
> latency Tx timestamp read").
> 
> [...]

Here is the summary with links:
  - [net-next,1/5] ice: handle extts in the miscellaneous interrupt thread
    https://git.kernel.org/netdev/net-next/c/6e8b2c88fc8c
  - [net-next,2/5] ice: always return IRQ_WAKE_THREAD in ice_misc_intr()
    https://git.kernel.org/netdev/net-next/c/d578e618f192
  - [net-next,3/5] ice: introduce ICE_TX_TSTAMP_WORK enumeration
    https://git.kernel.org/netdev/net-next/c/ae39eb42dd06
  - [net-next,4/5] ice: trigger PFINT_OICR_TSYN_TX interrupt instead of polling
    https://git.kernel.org/netdev/net-next/c/9a8648cce8d8
  - [net-next,5/5] ice: do not re-enable miscellaneous interrupt until thread_fn completes
    https://git.kernel.org/netdev/net-next/c/0ec38df36ea1

You are awesome, thank you!
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