ALSA: firewire-lib: fix calculation for size of IR context payload

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>

diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c
index e50e28f77e74e3308cd49a2647d1099b3eb76cb1..8297fe456a3373c19a50616fcbf6db9dc81f9e10 100644 (file)
--- a/sound/firewire/amdtp-stream.c
+++ b/sound/firewire/amdtp-stream.c
@@ -932,23 +932,22 @@ static int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed)
                s->ctx_data.rx.last_syt_offset = TICKS_PER_CYCLE;
        }
 
-       /* 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;
        }