firewire: allow explicit flushing of iso packet completions

Extend the kernel and userspace APIs to allow reporting all currently
completed isochronous packets, even if the next interrupt packet has not
yet been reached.  This is required to determine the status of the
packets at the end of a paused or stopped stream, and useful for more
precise synchronization of audio streams.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

1 files changed, 70 insertions, 8 deletions

diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 6325626..59e7894 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -172,6 +172,9 @@ struct iso_context {
 	struct context context;
 	void *header;
 	size_t header_length;
+	unsigned long flushing_completions;
+	u32 mc_buffer_bus;
+	u16 mc_completed;
 	u16 last_timestamp;
 	u8 sync;
 	u8 tags;
@@ -2749,28 +2752,51 @@ static int handle_ir_buffer_fill(struct context *context,
 {
 	struct iso_context *ctx =
 		container_of(context, struct iso_context, context);
+	unsigned int req_count, res_count, completed;
 	u32 buffer_dma;
 
-	if (last->res_count != 0)
+	req_count = le16_to_cpu(last->req_count);
+	res_count = le16_to_cpu(ACCESS_ONCE(last->res_count));
+	completed = req_count - res_count;
+	buffer_dma = le32_to_cpu(last->data_address);
+
+	if (completed > 0) {
+		ctx->mc_buffer_bus = buffer_dma;
+		ctx->mc_completed = completed;
+	}
+
+	if (res_count != 0)
 		/* Descriptor(s) not done yet, stop iteration */
 		return 0;
 
-	buffer_dma = le32_to_cpu(last->data_address);
 	dma_sync_single_range_for_cpu(context->ohci->card.device,
 				      buffer_dma & PAGE_MASK,
 				      buffer_dma & ~PAGE_MASK,
-				      le16_to_cpu(last->req_count),
-				      DMA_FROM_DEVICE);
+				      completed, DMA_FROM_DEVICE);
 
-	if (last->control & cpu_to_le16(DESCRIPTOR_IRQ_ALWAYS))
+	if (last->control & cpu_to_le16(DESCRIPTOR_IRQ_ALWAYS)) {
 		ctx->base.callback.mc(&ctx->base,
-				      le32_to_cpu(last->data_address) +
-				      le16_to_cpu(last->req_count),
+				      buffer_dma + completed,
 				      ctx->base.callback_data);
+		ctx->mc_completed = 0;
+	}
 
 	return 1;
 }
 
+static void flush_ir_buffer_fill(struct iso_context *ctx)
+{
+	dma_sync_single_range_for_cpu(ctx->context.ohci->card.device,
+				      ctx->mc_buffer_bus & PAGE_MASK,
+				      ctx->mc_buffer_bus & ~PAGE_MASK,
+				      ctx->mc_completed, DMA_FROM_DEVICE);
+
+	ctx->base.callback.mc(&ctx->base,
+			      ctx->mc_buffer_bus + ctx->mc_completed,
+			      ctx->base.callback_data);
+	ctx->mc_completed = 0;
+}
+
 static inline void sync_it_packet_for_cpu(struct context *context,
 					  struct descriptor *pd)
 {
@@ -2925,8 +2951,10 @@ static struct fw_iso_context *ohci_allocate_iso_context(struct fw_card *card,
 	if (ret < 0)
 		goto out_with_header;
 
-	if (type == FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL)
+	if (type == FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL) {
 		set_multichannel_mask(ohci, 0);
+		ctx->mc_completed = 0;
+	}
 
 	return &ctx->base;
 
@@ -3388,6 +3416,39 @@ static void ohci_flush_queue_iso(struct fw_iso_context *base)
 	reg_write(ctx->ohci, CONTROL_SET(ctx->regs), CONTEXT_WAKE);
 }
 
+static int ohci_flush_iso_completions(struct fw_iso_context *base)
+{
+	struct iso_context *ctx = container_of(base, struct iso_context, base);
+	int ret = 0;
+
+	tasklet_disable(&ctx->context.tasklet);
+
+	if (!test_and_set_bit_lock(0, &ctx->flushing_completions)) {
+		context_tasklet((unsigned long)&ctx->context);
+
+		switch (base->type) {
+		case FW_ISO_CONTEXT_TRANSMIT:
+		case FW_ISO_CONTEXT_RECEIVE:
+			if (ctx->header_length != 0)
+				flush_iso_completions(ctx);
+			break;
+		case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
+			if (ctx->mc_completed != 0)
+				flush_ir_buffer_fill(ctx);
+			break;
+		default:
+			ret = -ENOSYS;
+		}
+
+		clear_bit_unlock(0, &ctx->flushing_completions);
+		smp_mb__after_clear_bit();
+	}
+
+	tasklet_enable(&ctx->context.tasklet);
+
+	return ret;
+}
+
 static const struct fw_card_driver ohci_driver = {
 	.enable			= ohci_enable,
 	.read_phy_reg		= ohci_read_phy_reg,
@@ -3405,6 +3466,7 @@ static const struct fw_card_driver ohci_driver = {
 	.set_iso_channels	= ohci_set_iso_channels,
 	.queue_iso		= ohci_queue_iso,
 	.flush_queue_iso	= ohci_flush_queue_iso,
+	.flush_iso_completions	= ohci_flush_iso_completions,
 	.start_iso		= ohci_start_iso,
 	.stop_iso		= ohci_stop_iso,
 };