V4L/DVB (9723): cx18: Propagate staleness of mailbox and mdl ack data to work handler

cx18: Propagate staleness of mailbox and mdl ack data to work handler to let
the work handler know that the data from the encoder may not be coherent.
Allows for smarter handling of buffers in future, to deal with MDLs that fall
out of rotation due to irq handler being late in collecting mailbox and mdl ack
info.

Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/cx18/cx18-driver.h

@@ -245,13 +245,20 @@ struct cx18_dvb {
 struct cx18;	 /* forward reference */
 struct cx18_scb; /* forward reference */
 
+
 #define CX18_MAX_MDL_ACKS 2
 #define CX18_MAX_EPU_WORK_ORDERS 70 /* CPU_DE_RELEASE_MDL bursts 63 commands */
 
+#define CX18_F_EWO_MB_STALE_UPON_RECEIPT 0x1
+#define CX18_F_EWO_MB_STALE_WHILE_PROC   0x2
+#define CX18_F_EWO_MB_STALE \
+	     (CX18_F_EWO_MB_STALE_UPON_RECEIPT | CX18_F_EWO_MB_STALE_WHILE_PROC)
+
 struct cx18_epu_work_order {
 	struct work_struct work;
 	atomic_t pending;
 	struct cx18 *cx;
+	unsigned long flags;
 	int rpu;
 	struct cx18_mailbox mb;
 	struct cx18_mdl_ack mdl_ack[CX18_MAX_MDL_ACKS];

drivers/media/video/cx18/cx18-mailbox.c

@@ -233,7 +233,7 @@ void cx18_epu_work_handler(struct work_struct *work)
  * Functions that run in an interrupt handling context
  */
 
-static void mb_ack_irq(struct cx18 *cx, const struct cx18_epu_work_order *order)
+static void mb_ack_irq(struct cx18 *cx, struct cx18_epu_work_order *order)
 {
 	struct cx18_mailbox __iomem *ack_mb;
 	u32 ack_irq, req;
@@ -256,15 +256,20 @@ static void mb_ack_irq(struct cx18 *cx, const struct cx18_epu_work_order *order)
 	req = order->mb.request;
 	/* Don't ack if the RPU has gotten impatient and timed us out */
 	if (req != cx18_readl(cx, &ack_mb->request) ||
-	    req == cx18_readl(cx, &ack_mb->ack))
+	    req == cx18_readl(cx, &ack_mb->ack)) {
+		CX18_WARN("Possibly falling behind: %s self-ack'ed our incoming"
+			  " %s to EPU mailbox (sequence no. %u) while "
+			  "processing\n",
+			  rpu_str[order->rpu], rpu_str[order->rpu], req);
+		order->flags |= CX18_F_EWO_MB_STALE_WHILE_PROC;
 		return;
+	}
 	cx18_writel(cx, req, &ack_mb->ack);
 	cx18_write_reg_expect(cx, ack_irq, SW2_INT_SET, ack_irq, ack_irq);
 	return;
 }
 
-static int epu_dma_done_irq(struct cx18 *cx, struct cx18_epu_work_order *order,
-			    int stale)
+static int epu_dma_done_irq(struct cx18 *cx, struct cx18_epu_work_order *order)
 {
 	u32 handle, mdl_ack_offset, mdl_ack_count;
 	struct cx18_mailbox *mb;
@@ -276,20 +281,21 @@ static int epu_dma_done_irq(struct cx18 *cx, struct cx18_epu_work_order *order,
 
 	if (handle == CX18_INVALID_TASK_HANDLE ||
 	    mdl_ack_count == 0 || mdl_ack_count > CX18_MAX_MDL_ACKS) {
-		if (!stale)
+		if ((order->flags & CX18_F_EWO_MB_STALE) == 0)
 			mb_ack_irq(cx, order);
 		return -1;
 	}
 
 	cx18_memcpy_fromio(cx, order->mdl_ack, cx->enc_mem + mdl_ack_offset,
 			   sizeof(struct cx18_mdl_ack) * mdl_ack_count);
-	if (!stale)
+
+	if ((order->flags & CX18_F_EWO_MB_STALE) == 0)
 		mb_ack_irq(cx, order);
 	return 1;
 }
 
 static
-int epu_debug_irq(struct cx18 *cx, struct cx18_epu_work_order *order, int stale)
+int epu_debug_irq(struct cx18 *cx, struct cx18_epu_work_order *order)
 {
 	u32 str_offset;
 	char *str = order->str;
@@ -303,14 +309,14 @@ int epu_debug_irq(struct cx18 *cx, struct cx18_epu_work_order *order, int stale)
 		cx18_setup_page(cx, SCB_OFFSET);
 	}
 
-	if (!stale)
+	if ((order->flags & CX18_F_EWO_MB_STALE) == 0)
 		mb_ack_irq(cx, order);
 
 	return str_offset ? 1 : 0;
 }
 
 static inline
-int epu_cmd_irq(struct cx18 *cx, struct cx18_epu_work_order *order, int stale)
+int epu_cmd_irq(struct cx18 *cx, struct cx18_epu_work_order *order)
 {
 	int ret = -1;
 
@@ -319,10 +325,10 @@ int epu_cmd_irq(struct cx18 *cx, struct cx18_epu_work_order *order, int stale)
 	{
 		switch (order->mb.cmd) {
 		case CX18_EPU_DMA_DONE:
-			ret = epu_dma_done_irq(cx, order, stale);
+			ret = epu_dma_done_irq(cx, order);
 			break;
 		case CX18_EPU_DEBUG:
-			ret = epu_debug_irq(cx, order, stale);
+			ret = epu_debug_irq(cx, order);
 			break;
 		default:
 			CX18_WARN("Unknown CPU to EPU mailbox command %#0x\n",
@@ -370,7 +376,6 @@ void cx18_api_epu_cmd_irq(struct cx18 *cx, int rpu)
 	struct cx18_mailbox __iomem *mb;
 	struct cx18_mailbox *order_mb;
 	struct cx18_epu_work_order *order;
-	int stale = 0;
 	int submit;
 
 	switch (rpu) {
@@ -391,6 +396,7 @@ void cx18_api_epu_cmd_irq(struct cx18 *cx, int rpu)
 		return;
 	}
 
+	order->flags = 0;
 	order->rpu = rpu;
 	order_mb = &order->mb;
 	cx18_memcpy_fromio(cx, order_mb, mb, sizeof(struct cx18_mailbox));
@@ -400,14 +406,14 @@ void cx18_api_epu_cmd_irq(struct cx18 *cx, int rpu)
 			  " %s to EPU mailbox (sequence no. %u)\n",
 			  rpu_str[rpu], rpu_str[rpu], order_mb->request);
 		dump_mb(cx, order_mb, "incoming");
-		stale = 1;
+		order->flags = CX18_F_EWO_MB_STALE_UPON_RECEIPT;
 	}
 
 	/*
 	 * Individual EPU command processing is responsible for ack-ing
 	 * a non-stale mailbox as soon as possible
 	 */
-	submit = epu_cmd_irq(cx, order, stale);
+	submit = epu_cmd_irq(cx, order);
 	if (submit > 0) {
 		queue_work(cx18_work_queue, &order->work);
 	}