[PATCH 5.12 047/127] ALSA: firewire-lib: fix calculation for size of IR context payload

Greg Kroah-Hartman
2021-05-24T16:04:26Z

From: Takashi Sakamoto <o-takashi@sakamocchi.jp>

commit 1be4f21d9984fa9835fae5411a29465dc5aece6f upstream.

The quadlets for CIP header is handled as a part of IR context header,
thus it doesn't join in IR context payload. However current calculation
includes the quadlets in IR context payload.

Cc: <stable@vger.kernel.org>
Fixes: f11453c7cc01 ("ALSA: firewire-lib: use 16 bytes IR context header to separate CIP header")
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20210513125652.110249-5-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
sound/firewire/amdtp-stream.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)

--- a/sound/firewire/amdtp-stream.c
+++ b/sound/firewire/amdtp-stream.c
@@ -1068,23 +1068,22 @@ static int amdtp_stream_start(struct amd
s->data_block_counter = 0;
}

- /* initialize packet buffer */
+ // initialize packet buffer.
+ max_ctx_payload_size = amdtp_stream_get_max_payload(s);
if (s->direction == AMDTP_IN_STREAM) {
dir = DMA_FROM_DEVICE;
type = FW_ISO_CONTEXT_RECEIVE;
- if (!(s->flags & CIP_NO_HEADER))
+ if (!(s->flags & CIP_NO_HEADER)) {
+ max_ctx_payload_size -= 8;
ctx_header_size = IR_CTX_HEADER_SIZE_CIP;
- else
+ } else {
ctx_header_size = IR_CTX_HEADER_SIZE_NO_CIP;
-
- max_ctx_payload_size = amdtp_stream_get_max_payload(s) -
- ctx_header_size;
+ }
} else {
dir = DMA_TO_DEVICE;
type = FW_ISO_CONTEXT_TRANSMIT;
ctx_header_size = 0; // No effect for IT context.

- max_ctx_payload_size = amdtp_stream_get_max_payload(s);
if (!(s->flags & CIP_NO_HEADER))
max_ctx_payload_size -= IT_PKT_HEADER_SIZE_CIP;
}