cx18: Remove unnecessary MMIO accesses in time critical irq handling path

From: Andy Walls <awalls@radix.net>

Remove unnecessary MMIO accesses in time critical irq handling path.  Also
ensured that the mailbox ack field is read in last, so we know for sure if we
have a stale mailbox or not on receipt.

Priority: normal

Signed-off-by: Andy Walls <awalls@radix.net>

4 files changed, 22 insertions, 22 deletions

diff --git a/linux/drivers/media/video/cx18/cx18-driver.h b/linux/drivers/media/video/cx18/cx18-driver.h
index 02a82c3b7..cad352aeb 100644
--- a/linux/drivers/media/video/cx18/cx18-driver.h
+++ b/linux/drivers/media/video/cx18/cx18-driver.h
@@ -446,6 +446,10 @@ struct cx18 {
 	/* when the current DMA is finished this queue is woken up */
 	wait_queue_head_t dma_waitq;
 
+	u32 sw1_irq_mask;
+	u32 sw2_irq_mask;
+	u32 hw2_irq_mask;
+
 	struct cx18_epu_work_order epu_work_order[CX18_MAX_EPU_WORK_ORDERS];
 	char epu_debug_str[256]; /* CX18_EPU_DEBUG is rare: use shared space */
 
diff --git a/linux/drivers/media/video/cx18/cx18-io.c b/linux/drivers/media/video/cx18/cx18-io.c
index a2b5e807f..c6f1d0d7f 100644
--- a/linux/drivers/media/video/cx18/cx18-io.c
+++ b/linux/drivers/media/video/cx18/cx18-io.c
@@ -71,32 +71,28 @@ void cx18_memset_io(struct cx18 *cx, void __iomem *addr, int val, size_t count)
 
 void cx18_sw1_irq_enable(struct cx18 *cx, u32 val)
 {
-	u32 r;
 	cx18_write_reg_expect(cx, val, SW1_INT_STATUS, ~val, val);
-	r = cx18_read_reg(cx, SW1_INT_ENABLE_PCI);
-	cx18_write_reg(cx, r | val, SW1_INT_ENABLE_PCI);
+	cx->sw1_irq_mask = cx18_read_reg(cx, SW1_INT_ENABLE_PCI) | val;
+	cx18_write_reg(cx, cx->sw1_irq_mask, SW1_INT_ENABLE_PCI);
 }
 
 void cx18_sw1_irq_disable(struct cx18 *cx, u32 val)
 {
-	u32 r;
-	r = cx18_read_reg(cx, SW1_INT_ENABLE_PCI);
-	cx18_write_reg(cx, r & ~val, SW1_INT_ENABLE_PCI);
+	cx->sw1_irq_mask = cx18_read_reg(cx, SW1_INT_ENABLE_PCI) & ~val;
+	cx18_write_reg(cx, cx->sw1_irq_mask, SW1_INT_ENABLE_PCI);
 }
 
 void cx18_sw2_irq_enable(struct cx18 *cx, u32 val)
 {
-	u32 r;
 	cx18_write_reg_expect(cx, val, SW2_INT_STATUS, ~val, val);
-	r = cx18_read_reg(cx, SW2_INT_ENABLE_PCI);
-	cx18_write_reg(cx, r | val, SW2_INT_ENABLE_PCI);
+	cx->sw2_irq_mask = cx18_read_reg(cx, SW2_INT_ENABLE_PCI) | val;
+	cx18_write_reg(cx, cx->sw2_irq_mask, SW2_INT_ENABLE_PCI);
 }
 
 void cx18_sw2_irq_disable(struct cx18 *cx, u32 val)
 {
-	u32 r;
-	r = cx18_read_reg(cx, SW2_INT_ENABLE_PCI);
-	cx18_write_reg(cx, r & ~val, SW2_INT_ENABLE_PCI);
+	cx->sw2_irq_mask = cx18_read_reg(cx, SW2_INT_ENABLE_PCI) & ~val;
+	cx18_write_reg(cx, cx->sw2_irq_mask, SW2_INT_ENABLE_PCI);
 }
 
 void cx18_sw2_irq_disable_cpu(struct cx18 *cx, u32 val)
diff --git a/linux/drivers/media/video/cx18/cx18-irq.c b/linux/drivers/media/video/cx18/cx18-irq.c
index 52fc41521..34e25373e 100644
--- a/linux/drivers/media/video/cx18/cx18-irq.c
+++ b/linux/drivers/media/video/cx18/cx18-irq.c
@@ -48,16 +48,11 @@ irqreturn_t cx18_irq_handler(int irq, void *dev_id)
 #endif
 {
 	struct cx18 *cx = (struct cx18 *)dev_id;
-	u32 sw1, sw1_mask;
-	u32 sw2, sw2_mask;
-	u32 hw2, hw2_mask;
+	u32 sw1, sw2, hw2;
 
-	sw1_mask = cx18_read_reg(cx, SW1_INT_ENABLE_PCI);
-	sw1 = cx18_read_reg(cx, SW1_INT_STATUS) & sw1_mask;
-	sw2_mask = cx18_read_reg(cx, SW2_INT_ENABLE_PCI);
-	sw2 = cx18_read_reg(cx, SW2_INT_STATUS) & sw2_mask;
-	hw2_mask = cx18_read_reg(cx, HW2_INT_MASK5_PCI);
-	hw2 = cx18_read_reg(cx, HW2_INT_CLR_STATUS) & hw2_mask;
+	sw1 = cx18_read_reg(cx, SW1_INT_STATUS) & cx->sw1_irq_mask;
+	sw2 = cx18_read_reg(cx, SW2_INT_STATUS) & cx->sw2_irq_mask;
+	hw2 = cx18_read_reg(cx, HW2_INT_CLR_STATUS) & cx->hw2_irq_mask;
 
 	if (sw1)
 		cx18_write_reg_expect(cx, sw1, SW1_INT_STATUS, ~sw1, sw1);
diff --git a/linux/drivers/media/video/cx18/cx18-mailbox.c b/linux/drivers/media/video/cx18/cx18-mailbox.c
index c7fcd6507..6ad35d0f9 100644
--- a/linux/drivers/media/video/cx18/cx18-mailbox.c
+++ b/linux/drivers/media/video/cx18/cx18-mailbox.c
@@ -405,7 +405,12 @@ void cx18_api_epu_cmd_irq(struct cx18 *cx, int rpu)
 	order->flags = 0;
 	order->rpu = rpu;
 	order_mb = &order->mb;
-	cx18_memcpy_fromio(cx, order_mb, mb, sizeof(struct cx18_mailbox));
+
+	/* mb->cmd and mb->args[0] through mb->args[2] */
+	cx18_memcpy_fromio(cx, &order_mb->cmd, &mb->cmd, 4 * sizeof(u32));
+	/* mb->request and mb->ack.  N.B. we want to read mb->ack last */
+	cx18_memcpy_fromio(cx, &order_mb->request, &mb->request,
+			   2 * sizeof(u32));
 
 	if (order_mb->request == order_mb->ack) {
 		CX18_WARN("Possibly falling behind: %s self-ack'ed our incoming"