[ofa-general] [PATCH take2] IB/ipath -- shadow the gpio_mask register

[Arthur Jones]

Once upon a time, GPIO interrupts were rare.  But
then a chip bug in the waldo series forced the use of
a GPIO interrupt to signal packet reception.  This
greatly increased the frequency of GPIO interrupts
which have the gpio_mask bits set on the waldo chips.
Other bits in the gpio_status register are used for
I2C clock and data lines, these bits are usually on.
An "unlikely" annotation leftover from the old days
was improperly applied to these bits, and an unnecessary
chip mmio read was being accessed in the interrupt fast
path on waldo.

Remove the stagnant unlikely annotation in the interrupt
handler and keep a shadow copy of the gpio_mask register
to avoid the slow mmio read when testing for interruptable
GPIO bits.

Signed-off-by: Arthur Jones <arthur.jones at qlogic.com>
---

 drivers/infiniband/hw/ipath/ipath_iba6120.c |    7 +++----
 drivers/infiniband/hw/ipath/ipath_intr.c    |    7 +++----
 drivers/infiniband/hw/ipath/ipath_kernel.h  |    2 ++
 drivers/infiniband/hw/ipath/ipath_verbs.c   |   12 ++++++------
 4 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/infiniband/hw/ipath/ipath_iba6120.c b/drivers/infiniband/hw/ipath/ipath_iba6120.c
index fb58154..c21d99b 100644
--- a/drivers/infiniband/hw/ipath/ipath_iba6120.c
+++ b/drivers/infiniband/hw/ipath/ipath_iba6120.c
@@ -747,7 +747,6 @@ static void ipath_pe_quiet_serdes(struct ipath_devdata *dd)
 
 static int ipath_pe_intconfig(struct ipath_devdata *dd)
 {
-	u64 val;
 	u32 chiprev;
 
 	/*
@@ -760,9 +759,9 @@ static int ipath_pe_intconfig(struct ipath_devdata *dd)
 	if ((chiprev & INFINIPATH_R_CHIPREVMINOR_MASK) > 1) {
 		/* Rev2+ reports extra errors via internal GPIO pins */
 		dd->ipath_flags |= IPATH_GPIO_ERRINTRS;
-		val = ipath_read_kreg64(dd, dd->ipath_kregs->kr_gpio_mask);
-		val |= IPATH_GPIO_ERRINTR_MASK;
-		ipath_write_kreg( dd, dd->ipath_kregs->kr_gpio_mask, val);
+		dd->ipath_gpio_mask |= IPATH_GPIO_ERRINTR_MASK;
+		ipath_write_kreg(dd, dd->ipath_kregs->kr_gpio_mask,
+				 dd->ipath_gpio_mask);
 	}
 	return 0;
 }
diff --git a/drivers/infiniband/hw/ipath/ipath_intr.c b/drivers/infiniband/hw/ipath/ipath_intr.c
index 45d0331..a90d3b5 100644
--- a/drivers/infiniband/hw/ipath/ipath_intr.c
+++ b/drivers/infiniband/hw/ipath/ipath_intr.c
@@ -1056,7 +1056,7 @@ irqreturn_t ipath_intr(int irq, void *data)
 			gpiostatus &= ~(1 << IPATH_GPIO_PORT0_BIT);
 			chk0rcv = 1;
 		}
-		if (unlikely(gpiostatus)) {
+		if (gpiostatus) {
 			/*
 			 * Some unexpected bits remain. If they could have
 			 * caused the interrupt, complain and clear.
@@ -1065,9 +1065,8 @@ irqreturn_t ipath_intr(int irq, void *data)
 			 * GPIO interrupts, possibly on a "three strikes"
 			 * basis.
 			 */
-			u32 mask;
-			mask = ipath_read_kreg32(
-				dd, dd->ipath_kregs->kr_gpio_mask);
+			const u32 mask = (u32) dd->ipath_gpio_mask;
+
 			if (mask & gpiostatus) {
 				ipath_dbg("Unexpected GPIO IRQ bits %x\n",
 				  gpiostatus & mask);
diff --git a/drivers/infiniband/hw/ipath/ipath_kernel.h b/drivers/infiniband/hw/ipath/ipath_kernel.h
index e900c25..12194f3 100644
--- a/drivers/infiniband/hw/ipath/ipath_kernel.h
+++ b/drivers/infiniband/hw/ipath/ipath_kernel.h
@@ -397,6 +397,8 @@ struct ipath_devdata {
 	unsigned long ipath_pioavailshadow[8];
 	/* shadow of kr_gpio_out, for rmw ops */
 	u64 ipath_gpio_out;
+	/* shadow the gpio mask register */
+	u64 ipath_gpio_mask;
 	/* kr_revision shadow */
 	u64 ipath_revision;
 	/*
diff --git a/drivers/infiniband/hw/ipath/ipath_verbs.c b/drivers/infiniband/hw/ipath/ipath_verbs.c
index 12933e7..bb70845 100644
--- a/drivers/infiniband/hw/ipath/ipath_verbs.c
+++ b/drivers/infiniband/hw/ipath/ipath_verbs.c
@@ -1387,13 +1387,12 @@ static int enable_timer(struct ipath_devdata *dd)
 	 * processing.
 	 */
 	if (dd->ipath_flags & IPATH_GPIO_INTR) {
-		u64 val;
 		ipath_write_kreg(dd, dd->ipath_kregs->kr_debugportselect,
 				 0x2074076542310ULL);
 		/* Enable GPIO bit 2 interrupt */
-		val = ipath_read_kreg64(dd, dd->ipath_kregs->kr_gpio_mask);
-		val |= (u64) (1 << IPATH_GPIO_PORT0_BIT);
-		ipath_write_kreg( dd, dd->ipath_kregs->kr_gpio_mask, val);
+		dd->ipath_gpio_mask |= (u64) (1 << IPATH_GPIO_PORT0_BIT);
+		ipath_write_kreg(dd, dd->ipath_kregs->kr_gpio_mask,
+				 dd->ipath_gpio_mask);
 	}
 
 	init_timer(&dd->verbs_timer);
@@ -1412,8 +1411,9 @@ static int disable_timer(struct ipath_devdata *dd)
                 u64 val;
                 /* Disable GPIO bit 2 interrupt */
                 val = ipath_read_kreg64(dd, dd->ipath_kregs->kr_gpio_mask);
-                val &= ~((u64) (1 << IPATH_GPIO_PORT0_BIT));
-                ipath_write_kreg( dd, dd->ipath_kregs->kr_gpio_mask, val);
+		dd->ipath_gpio_mask &= ~((u64) (1 << IPATH_GPIO_PORT0_BIT));
+		ipath_write_kreg(dd, dd->ipath_kregs->kr_gpio_mask,
+				 dd->ipath_gpio_mask);
 		/*
 		 * We might want to undo changes to debugportselect,
 		 * but how?