ice: implement and use rd32_poll_timeout for ice_sq_done timeout

The ice_sq_done function is used to check the control queue head register
and determine whether or not the control queue processing is done. This
function is called in a loop checking against jiffies for a specified
timeout.

The pattern of reading a register in a loop until a condition is true or a
timeout is reached is a relatively common pattern. In fact, the kernel
provides a read_poll_timeout function implementing this behavior in
<linux/iopoll.h>

Use of read_poll_timeout is preferred over directly coding these loops.
However, using it in the ice driver is a bit more difficult because of the
rd32 wrapper. Implement a rd32_poll_timeout wrapper based on
read_poll_timeout.

Refactor ice_sq_done to use rd32_poll_timeout, replacing the loop calling
ice_sq_done in ice_sq_send_cmd. This simplifies the logic down to a single
ice_sq_done() call.

The implementation of rd32_poll_timeout uses microseconds for its timeout
value, so update the CQ timeout macros used to be specified in microseconds
units as well instead of using HZ for jiffies.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/ice/ice_controlq.c

@@ -933,19 +933,29 @@ static void ice_debug_cq(struct ice_hw *hw, void *desc, void *buf, u16 buf_len)
 }
 
 /**
- * ice_sq_done - check if FW has processed the Admin Send Queue (ATQ)
+ * ice_sq_done - poll until the last send on a control queue has completed
  * @hw: pointer to the HW struct
  * @cq: pointer to the specific Control queue
  *
- * Returns true if the firmware has processed all descriptors on the
- * admin send queue. Returns false if there are still requests pending.
+ * Use read_poll_timeout to poll the control queue head, checking until it
+ * matches next_to_use. According to the control queue designers, this has
+ * better timing reliability than the DD bit.
+ *
+ * Return: true if all the descriptors on the send side of a control queue
+ *         are finished processing, false otherwise.
  */
 static bool ice_sq_done(struct ice_hw *hw, struct ice_ctl_q_info *cq)
 {
-	/* AQ designers suggest use of head for better
-	 * timing reliability than DD bit
+	u32 head;
+
+	/* Wait a short time before the initial check, to allow hardware time
+	 * for completion.
 	 */
-	return rd32(hw, cq->sq.head) == cq->sq.next_to_use;
+	udelay(5);
+
+	return !rd32_poll_timeout(hw, cq->sq.head,
+				  head, head == cq->sq.next_to_use,
+				  20, ICE_CTL_Q_SQ_CMD_TIMEOUT);
 }
 
 /**
@@ -969,7 +979,6 @@ ice_sq_send_cmd(struct ice_hw *hw, struct ice_ctl_q_info *cq,
 	struct ice_aq_desc *desc_on_ring;
 	bool cmd_completed = false;
 	struct ice_sq_cd *details;
-	unsigned long timeout;
 	int status = 0;
 	u16 retval = 0;
 	u32 val = 0;
@@ -1063,20 +1072,9 @@ ice_sq_send_cmd(struct ice_hw *hw, struct ice_ctl_q_info *cq,
 	wr32(hw, cq->sq.tail, cq->sq.next_to_use);
 	ice_flush(hw);
 
-	/* Wait a short time before initial ice_sq_done() check, to allow
-	 * hardware time for completion.
+	/* Wait for the command to complete. If it finishes within the
+	 * timeout, copy the descriptor back to temp.
 	 */
-	udelay(5);
-
-	timeout = jiffies + ICE_CTL_Q_SQ_CMD_TIMEOUT;
-	do {
-		if (ice_sq_done(hw, cq))
-			break;
-
-		usleep_range(100, 150);
-	} while (time_before(jiffies, timeout));
-
-	/* if ready, copy the desc back to temp */
 	if (ice_sq_done(hw, cq)) {
 		memcpy(desc, desc_on_ring, sizeof(*desc));
 		if (buf) {

drivers/net/ethernet/intel/ice/ice_controlq.h

@@ -43,7 +43,7 @@ enum ice_ctl_q {
 };
 
 /* Control Queue timeout settings - max delay 1s */
-#define ICE_CTL_Q_SQ_CMD_TIMEOUT	HZ    /* Wait max 1s */
+#define ICE_CTL_Q_SQ_CMD_TIMEOUT	USEC_PER_SEC
 #define ICE_CTL_Q_ADMIN_INIT_TIMEOUT	10    /* Count 10 times */
 #define ICE_CTL_Q_ADMIN_INIT_MSEC	100   /* Check every 100msec */
 

drivers/net/ethernet/intel/ice/ice_osdep.h

@@ -12,6 +12,7 @@
 #include <linux/ethtool.h>
 #include <linux/etherdevice.h>
 #include <linux/if_ether.h>
+#include <linux/iopoll.h>
 #include <linux/pci_ids.h>
 #ifndef CONFIG_64BIT
 #include <linux/io-64-nonatomic-lo-hi.h>
@@ -23,6 +24,9 @@
 #define wr64(a, reg, value)	writeq((value), ((a)->hw_addr + (reg)))
 #define rd64(a, reg)		readq((a)->hw_addr + (reg))
 
+#define rd32_poll_timeout(a, addr, val, cond, delay_us, timeout_us) \
+	read_poll_timeout(rd32, val, cond, delay_us, timeout_us, false, a, addr)
+
 #define ice_flush(a)		rd32((a), GLGEN_STAT)
 #define ICE_M(m, s)		((m ## U) << (s))