V4L/DVB (9720): cx18: Major rewrite of interrupt handling for incoming mailbox processing

A major rewrite of interrupt handling for incoming mailbox processing, to split
the timing critical steps from the the deferrable steps as the sending XPU on
the CX23418 will time out and overwrite our incoming mailboxes rather quickly.
Setup a pool of work "order forms" for the irq handler to send jobs to the new
work handler routine which uses the kernel default work queue to do the
deferrable work.  Started optimizing some of the cx18-io calls as they are now
the low hanging fruit for recoving microseconds back from the timeline.
Future optimizations will get rid of mmio read retries, mmio stats logging, and
combine smaller functions in the irq path into the larger ones to save ~2 us
each.

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

1 files changed, 308 insertions, 10 deletions

diff --git a/drivers/media/video/cx18/cx18-mailbox.c b/drivers/media/video/cx18/cx18-mailbox.c
index 35f7188..3d210d2 100644
--- a/drivers/media/video/cx18/cx18-mailbox.c
+++ b/drivers/media/video/cx18/cx18-mailbox.c
@@ -26,6 +26,10 @@
 #include "cx18-scb.h"
 #include "cx18-irq.h"
 #include "cx18-mailbox.h"
+#include "cx18-queue.h"
+#include "cx18-streams.h"
+
+static const char *rpu_str[] = { "APU", "CPU", "EPU", "HPU" };
 
 #define API_FAST (1 << 2) /* Short timeout */
 #define API_SLOW (1 << 3) /* Additional 300ms timeout */
@@ -92,12 +96,149 @@ static const struct cx18_api_info *find_api_info(u32 cmd)
 	return NULL;
 }
 
-long cx18_mb_ack(struct cx18 *cx, const struct cx18_mailbox *mb, int rpu)
+static void dump_mb(struct cx18 *cx, struct cx18_mailbox *mb, char *name)
+{
+	char argstr[MAX_MB_ARGUMENTS*11+1];
+	char *p;
+	int i;
+
+	if (!(cx18_debug & CX18_DBGFLG_API))
+		return;
+
+	for (i = 0, p = argstr; i < MAX_MB_ARGUMENTS; i++, p += 11) {
+		/* kernel snprintf() appends '\0' always */
+		snprintf(p, 12, " %#010x", mb->args[i]);
+	}
+	CX18_DEBUG_API("%s: req %#010x ack %#010x cmd %#010x err %#010x args%s"
+		"\n", name, mb->request, mb->ack, mb->cmd, mb->error, argstr);
+}
+
+
+/*
+ * Functions that run in a work_queue work handling context
+ */
+
+static void epu_dma_done(struct cx18 *cx, struct cx18_epu_work_order *order)
+{
+	u32 handle, mdl_ack_count;
+	struct cx18_mailbox *mb;
+	struct cx18_mdl_ack *mdl_ack;
+	struct cx18_stream *s;
+	struct cx18_buffer *buf;
+	int i;
+
+	mb = &order->mb;
+	handle = mb->args[0];
+	s = cx18_handle_to_stream(cx, handle);
+
+	if (s == NULL) {
+		CX18_WARN("Got DMA done notification for unknown/inactive"
+			  " handle %d\n", handle);
+		return;
+	}
+
+	mdl_ack_count = mb->args[2];
+	mdl_ack = order->mdl_ack;
+	for (i = 0; i < mdl_ack_count; i++, mdl_ack++) {
+		buf = cx18_queue_get_buf(s, mdl_ack->id, mdl_ack->data_used);
+		CX18_DEBUG_HI_DMA("DMA DONE for %s (buffer %d)\n", s->name,
+				  mdl_ack->id);
+		if (buf == NULL) {
+			CX18_WARN("Could not find buf %d for stream %s\n",
+				  mdl_ack->id, s->name);
+			continue;
+		}
+
+		cx18_buf_sync_for_cpu(s, buf);
+		if (s->type == CX18_ENC_STREAM_TYPE_TS && s->dvb.enabled) {
+			CX18_DEBUG_HI_DMA("TS recv bytesused = %d\n",
+					  buf->bytesused);
+
+			dvb_dmx_swfilter(&s->dvb.demux, buf->buf,
+					 buf->bytesused);
+
+			cx18_buf_sync_for_device(s, buf);
+
+			if (s->handle != CX18_INVALID_TASK_HANDLE &&
+			    test_bit(CX18_F_S_STREAMING, &s->s_flags))
+				cx18_vapi(cx,
+				       CX18_CPU_DE_SET_MDL, 5, s->handle,
+				       (void __iomem *)
+				       &cx->scb->cpu_mdl[buf->id] - cx->enc_mem,
+				       1, buf->id, s->buf_size);
+		} else
+			set_bit(CX18_F_B_NEED_BUF_SWAP, &buf->b_flags);
+	}
+	wake_up(&cx->dma_waitq);
+	if (s->id != -1)
+		wake_up(&s->waitq);
+}
+
+static void epu_debug(struct cx18 *cx, struct cx18_epu_work_order *order)
+{
+	char *p;
+	char *str = order->str;
+
+	CX18_DEBUG_INFO("%x %s\n", order->mb.args[0], str);
+	p = strchr(str, '.');
+	if (!test_bit(CX18_F_I_LOADED_FW, &cx->i_flags) && p && p > str)
+		CX18_INFO("FW version: %s\n", p - 1);
+}
+
+static void epu_cmd(struct cx18 *cx, struct cx18_epu_work_order *order)
+{
+	switch (order->rpu) {
+	case CPU:
+	{
+		switch (order->mb.cmd) {
+		case CX18_EPU_DMA_DONE:
+			epu_dma_done(cx, order);
+			break;
+		case CX18_EPU_DEBUG:
+			epu_debug(cx, order);
+			break;
+		default:
+			CX18_WARN("Unknown CPU to EPU mailbox command %#0x\n",
+				  order->mb.cmd);
+			break;
+		}
+		break;
+	}
+	case APU:
+		CX18_WARN("Unknown APU to EPU mailbox command %#0x\n",
+			  order->mb.cmd);
+		break;
+	default:
+		break;
+	}
+}
+
+static
+void free_epu_work_order(struct cx18 *cx, struct cx18_epu_work_order *order)
+{
+	atomic_set(&order->pending, 0);
+}
+
+void cx18_epu_work_handler(struct work_struct *work)
+{
+	struct cx18_epu_work_order *order =
+			container_of(work, struct cx18_epu_work_order, work);
+	struct cx18 *cx = order->cx;
+	epu_cmd(cx, order);
+	free_epu_work_order(cx, order);
+}
+
+
+/*
+ * Functions that run in an interrupt handling context
+ */
+
+static void mb_ack_irq(struct cx18 *cx, const struct cx18_epu_work_order *order)
 {
 	struct cx18_mailbox __iomem *ack_mb;
-	u32 ack_irq;
+	u32 ack_irq, req;
 
-	switch (rpu) {
+	switch (order->rpu) {
 	case APU:
 		ack_irq = IRQ_EPU_TO_APU_ACK;
 		ack_mb = &cx->scb->apu2epu_mb;
@@ -108,16 +249,175 @@ long cx18_mb_ack(struct cx18 *cx, const struct cx18_mailbox *mb, int rpu)
 		break;
 	default:
 		CX18_WARN("Unhandled RPU (%d) for command %x ack\n",
-			  rpu, mb->cmd);
-		return -EINVAL;
+			  order->rpu, order->mb.cmd);
+		return;
 	}
 
-	cx18_setup_page(cx, SCB_OFFSET);
-	cx18_write_sync(cx, mb->request, &ack_mb->ack);
+	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))
+		return;
+	cx18_writel(cx, req, &ack_mb->ack);
 	cx18_write_reg_expect(cx, ack_irq, SW2_INT_SET, ack_irq, ack_irq);
-	return 0;
+	return;
+}
+
+static int epu_dma_done_irq(struct cx18 *cx, struct cx18_epu_work_order *order,
+			    int stale)
+{
+	u32 handle, mdl_ack_offset, mdl_ack_count;
+	struct cx18_mailbox *mb;
+
+	mb = &order->mb;
+	handle = mb->args[0];
+	mdl_ack_offset = mb->args[1];
+	mdl_ack_count = mb->args[2];
+
+	if (handle == CX18_INVALID_TASK_HANDLE ||
+	    mdl_ack_count == 0 || mdl_ack_count > CX18_MAX_MDL_ACKS) {
+		if (!stale)
+			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)
+		mb_ack_irq(cx, order);
+	return 1;
+}
+
+static
+int epu_debug_irq(struct cx18 *cx, struct cx18_epu_work_order *order, int stale)
+{
+	u32 str_offset;
+	char *str = order->str;
+
+	str[0] = '\0';
+	str_offset = order->mb.args[1];
+	if (str_offset) {
+		cx18_setup_page(cx, str_offset);
+		cx18_memcpy_fromio(cx, str, cx->enc_mem + str_offset, 252);
+		str[252] = '\0';
+		cx18_setup_page(cx, SCB_OFFSET);
+	}
+
+	if (!stale)
+		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 ret = -1;
+
+	switch (order->rpu) {
+	case CPU:
+	{
+		switch (order->mb.cmd) {
+		case CX18_EPU_DMA_DONE:
+			ret = epu_dma_done_irq(cx, order, stale);
+			break;
+		case CX18_EPU_DEBUG:
+			ret = epu_debug_irq(cx, order, stale);
+			break;
+		default:
+			CX18_WARN("Unknown CPU to EPU mailbox command %#0x\n",
+				  order->mb.cmd);
+			break;
+		}
+		break;
+	}
+	case APU:
+		CX18_WARN("Unknown APU to EPU mailbox command %#0x\n",
+			  order->mb.cmd);
+		break;
+	default:
+		break;
+	}
+	return ret;
+}
+
+static inline
+struct cx18_epu_work_order *alloc_epu_work_order_irq(struct cx18 *cx)
+{
+	int i;
+	struct cx18_epu_work_order *order = NULL;
+
+	for (i = 0; i < CX18_MAX_EPU_WORK_ORDERS; i++) {
+		/*
+		 * We only need "pending" atomic to inspect its contents,
+		 * and need not do a check and set because:
+		 * 1. Any work handler thread only clears "pending" and only
+		 * on one, particular work order at a time, per handler thread.
+		 * 2. "pending" is only set here, and we're serialized because
+		 * we're called in an IRQ handler context.
+		 */
+		if (atomic_read(&cx->epu_work_order[i].pending) == 0) {
+			order = &cx->epu_work_order[i];
+			atomic_set(&order->pending, 1);
+			break;
+		}
+	}
+	return order;
 }
 
+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) {
+	case CPU:
+		mb = &cx->scb->cpu2epu_mb;
+		break;
+	case APU:
+		mb = &cx->scb->apu2epu_mb;
+		break;
+	default:
+		return;
+	}
+
+	order = alloc_epu_work_order_irq(cx);
+	if (order == NULL) {
+		CX18_WARN("Unable to find blank work order form to schedule "
+			  "incoming mailbox command processing\n");
+		return;
+	}
+
+	order->rpu = rpu;
+	order_mb = &order->mb;
+	cx18_memcpy_fromio(cx, order_mb, mb, sizeof(struct cx18_mailbox));
+
+	if (order_mb->request == order_mb->ack) {
+		CX18_WARN("Possibly falling behind: %s self-ack'ed our incoming"
+			  " %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;
+	}
+
+	/*
+	 * Individual EPU command processing is responsible for ack-ing
+	 * a non-stale mailbox as soon as possible
+	 */
+	submit = epu_cmd_irq(cx, order, stale);
+	if (submit > 0) {
+		schedule_work(&order->work);
+	}
+}
+
+
+/*
+ * Functions called from a non-interrupt, non work_queue context
+ */
+
 static void cx18_api_log_ack_delay(struct cx18 *cx, int msecs)
 {
 	if (msecs > CX18_MAX_MB_ACK_DELAY)
@@ -167,8 +467,6 @@ static int cx18_api_call(struct cx18 *cx, u32 cmd, int args, u32 data[])
 	}
 
 	mutex_lock(mb_lock);
-	cx18_setup_page(cx, SCB_OFFSET);
-
 	/*
 	 * Wait for an in-use mailbox to complete
 	 *