firewire: core: add tracepoints events for setting channels of multichannel context

It is helpful to trace the channel setting for the multichannel isochronous
context when the core function is requested it by both in-kernel unit
drivers and userspace applications.

This commit adds some tracepoints events for the aim.

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Takashi Sakamoto <[email protected]>

Author: takaswie

drivers/firewire/core-iso.c

@@ -177,6 +177,8 @@ EXPORT_SYMBOL(fw_iso_context_start);
 
 int fw_iso_context_set_channels(struct fw_iso_context *ctx, u64 *channels)
 {
+	trace_isoc_inbound_multiple_channels(ctx, *channels);
+
 	return ctx->card->driver->set_iso_channels(ctx, channels);
 }
 

include/trace/events/firewire.h

@@ -541,6 +541,27 @@ DEFINE_EVENT_CONDITION(isoc_destroy_template, isoc_inbound_multiple_destroy,
 	TP_CONDITION(ctx->type == FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL)
 );
 
+TRACE_EVENT(isoc_inbound_multiple_channels,
+	TP_PROTO(const struct fw_iso_context *ctx, u64 channels),
+	TP_ARGS(ctx, channels),
+	TP_STRUCT__entry(
+		__field(u64, context)
+		__field(u8, card_index)
+		__field(u64, channels)
+	),
+	TP_fast_assign(
+		__entry->context = (uintptr_t)ctx;
+		__entry->card_index = ctx->card->index;
+		__entry->channels = channels;
+	),
+	TP_printk(
+		"context=0x%llx card_index=%u channels=0x%016llx",
+		__entry->context,
+		__entry->card_index,
+		__entry->channels
+	)
+);
+
 #undef QUADLET_SIZE
 
 #endif // _FIREWIRE_TRACE_EVENT_H