ALSA: compress_offload: Add 64-bit safe timestamp infrastructure

The copied_total field in struct snd_compr_tstamp is a 32-bit
value that can overflow on long-running high-bitrate streams,
leading to incorrect calculations for buffer availablility.

This patch adds a 64-bit safe timestamping mechanism.
A new UAPI struct, snd_compr_tstamp64, is added which uses 64-bit
types for byte counters. The relevant ops structures across the
ASoC and core compress code are updated to use this new struct.
ASoC drivers are updated to use u64 counters.

Internal timestamps being u64 now, a compatibility function is added
to convert the 64-bit timestamp back to the 32-bit format for legacy
ioctl callers.

Reviewed-by: Miller Liang <millerliang@google.com>
Tested-by: Joris Verhaegen <verhaegen@google.com>
Signed-off-by: Joris Verhaegen <verhaegen@google.com>
Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@oss.qualcomm.com>
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20250905091301.2711705-2-verhaegen@google.com

4 files changed, 26 insertions, 6 deletions

diff --git a/include/sound/compress_driver.h b/include/sound/compress_driver.h
index b55c9eeb2b54..9e3d801e45ec 100644
--- a/include/sound/compress_driver.h
+++ b/include/sound/compress_driver.h
@@ -161,7 +161,7 @@ struct snd_compr_ops {
 			struct snd_compr_metadata *metadata);
 	int (*trigger)(struct snd_compr_stream *stream, int cmd);
 	int (*pointer)(struct snd_compr_stream *stream,
-			struct snd_compr_tstamp *tstamp);
+		       struct snd_compr_tstamp64 *tstamp);
 	int (*copy)(struct snd_compr_stream *stream, char __user *buf,
 		       size_t count);
 	int (*mmap)(struct snd_compr_stream *stream,
diff --git a/include/sound/soc-component.h b/include/sound/soc-component.h
index 2caa807c6249..cdb536c4ab2b 100644
--- a/include/sound/soc-component.h
+++ b/include/sound/soc-component.h
@@ -47,7 +47,7 @@ struct snd_compress_ops {
 		       struct snd_compr_stream *stream, int cmd);
 	int (*pointer)(struct snd_soc_component *component,
 		       struct snd_compr_stream *stream,
-		       struct snd_compr_tstamp *tstamp);
+		       struct snd_compr_tstamp64 *tstamp);
 	int (*copy)(struct snd_soc_component *component,
 		    struct snd_compr_stream *stream, char __user *buf,
 		    size_t count);
@@ -498,7 +498,7 @@ int snd_soc_component_compr_get_codec_caps(struct snd_compr_stream *cstream,
 					   struct snd_compr_codec_caps *codec);
 int snd_soc_component_compr_ack(struct snd_compr_stream *cstream, size_t bytes);
 int snd_soc_component_compr_pointer(struct snd_compr_stream *cstream,
-				    struct snd_compr_tstamp *tstamp);
+				    struct snd_compr_tstamp64 *tstamp);
 int snd_soc_component_compr_copy(struct snd_compr_stream *cstream,
 				 char __user *buf, size_t count);
 int snd_soc_component_compr_set_metadata(struct snd_compr_stream *cstream,
diff --git a/include/sound/soc-dai.h b/include/sound/soc-dai.h
index 166c29557e9d..224396927aef 100644
--- a/include/sound/soc-dai.h
+++ b/include/sound/soc-dai.h
@@ -256,7 +256,7 @@ int snd_soc_dai_compr_ack(struct snd_soc_dai *dai,
 			  size_t bytes);
 int snd_soc_dai_compr_pointer(struct snd_soc_dai *dai,
 			      struct snd_compr_stream *cstream,
-			      struct snd_compr_tstamp *tstamp);
+			      struct snd_compr_tstamp64 *tstamp);
 int snd_soc_dai_compr_set_metadata(struct snd_soc_dai *dai,
 				   struct snd_compr_stream *cstream,
 				   struct snd_compr_metadata *metadata);
@@ -383,8 +383,9 @@ struct snd_soc_cdai_ops {
 			struct snd_compr_metadata *, struct snd_soc_dai *);
 	int (*trigger)(struct snd_compr_stream *, int,
 			struct snd_soc_dai *);
-	int (*pointer)(struct snd_compr_stream *,
-			struct snd_compr_tstamp *, struct snd_soc_dai *);
+	int (*pointer)(struct snd_compr_stream *stream,
+		       struct snd_compr_tstamp64 *tstamp,
+		       struct snd_soc_dai *dai);
 	int (*ack)(struct snd_compr_stream *, size_t,
 			struct snd_soc_dai *);
 };
diff --git a/include/uapi/sound/compress_offload.h b/include/uapi/sound/compress_offload.h
index d62eb93af0ed..abd0ea3f86ee 100644
--- a/include/uapi/sound/compress_offload.h
+++ b/include/uapi/sound/compress_offload.h
@@ -57,6 +57,25 @@ struct snd_compr_tstamp {
 } __attribute__((packed, aligned(4)));
 
 /**
+ * struct snd_compr_tstamp64 - timestamp descriptor with fields in 64 bit
+ * @byte_offset: Byte offset in ring buffer to DSP
+ * @copied_total: Total number of bytes copied from/to ring buffer to/by DSP
+ * @pcm_frames: Frames decoded or encoded by DSP. This field will evolve by
+ *	large steps and should only be used to monitor encoding/decoding
+ *	progress. It shall not be used for timing estimates.
+ * @pcm_io_frames: Frames rendered or received by DSP into a mixer or an audio
+ * output/input. This field should be used for A/V sync or time estimates.
+ * @sampling_rate: sampling rate of audio
+ */
+struct snd_compr_tstamp64 {
+	__u32 byte_offset;
+	__u64 copied_total;
+	__u64 pcm_frames;
+	__u64 pcm_io_frames;
+	__u32 sampling_rate;
+} __attribute__((packed, aligned(4)));
+
+/**
  * struct snd_compr_avail - avail descriptor
  * @avail: Number of bytes available in ring buffer for writing/reading
  * @tstamp: timestamp information