V4L/DVB (13902): cx18: Update MPEG Index stream buffers module option processing

Update the module options related to INDEX stream buffer allocation.  A single
CX2341[5678] index entry is only 24 bytes.  Large buffers for the IDX stream
will prevent the CX23418 from transferring index data over at all.  Buffers
of around 1.5 kB or 64 index entries seem to be just fine.  We'll default to
63 buffers/MDLs as that is the firmware limit per stream and IDX stream buffers
are not high rate.  There is no reason on earth to allocate the previous 1 MB
default of buffer space for the IDX stream.

This is in anticipation of implementing the G_ENC_INDEX ioctl() in the cx18
driver.

Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 25 insertions, 8 deletions

diff --git a/drivers/media/video/cx18/cx18-driver.c b/drivers/media/video/cx18/cx18-driver.c
index 7f65a47f12e..458f5f07237 100644
--- a/drivers/media/video/cx18/cx18-driver.c
+++ b/drivers/media/video/cx18/cx18-driver.c
@@ -91,7 +91,7 @@ static int enc_pcm_bufsize = CX18_DEFAULT_ENC_PCM_BUFSIZE;
 
 static int enc_ts_bufs = -1;
 static int enc_mpg_bufs = -1;
-static int enc_idx_bufs = -1;
+static int enc_idx_bufs = CX18_MAX_FW_MDLS_PER_STREAM;
 static int enc_yuv_bufs = -1;
 static int enc_vbi_bufs = -1;
 static int enc_pcm_bufs = -1;
@@ -196,14 +196,17 @@ MODULE_PARM_DESC(enc_mpg_bufs,
                  "Number of encoder MPG buffers\n"
                  "\t\t\tDefault is computed from other enc_mpg_* parameters");
 MODULE_PARM_DESC(enc_idx_buffers,
-                 "Encoder IDX buffer memory (MB). (enc_idx_bufs can override)\n"
-                 "\t\t\tDefault: " __stringify(CX18_DEFAULT_ENC_IDX_BUFFERS));
+                 "(Deprecated) Encoder IDX buffer memory (MB)\n"
+                 "\t\t\tIgnored, except 0 disables IDX buffer allocations\n"
+                 "\t\t\tDefault: 1 [Enabled]");
 MODULE_PARM_DESC(enc_idx_bufsize,
                  "Size of an encoder IDX buffer (kB)\n"
-                 "\t\t\tDefault: " __stringify(CX18_DEFAULT_ENC_IDX_BUFSIZE));
+                 "\t\t\tAllowed values are multiples of 1.5 kB rounded up\n"
+                 "\t\t\t(multiples of size required for 64 index entries)\n"
+                 "\t\t\tDefault: 2");
 MODULE_PARM_DESC(enc_idx_bufs,
                  "Number of encoder IDX buffers\n"
-                 "\t\t\tDefault is computed from other enc_idx_* parameters");
+                 "\t\t\tDefault: " __stringify(CX18_MAX_FW_MDLS_PER_STREAM));
 MODULE_PARM_DESC(enc_yuv_buffers,
                  "Encoder YUV buffer memory (MB). (enc_yuv_bufs can override)\n"
                  "\t\t\tDefault: " __stringify(CX18_DEFAULT_ENC_YUV_BUFFERS));
@@ -501,7 +504,12 @@ static void cx18_process_options(struct cx18 *cx)
                 /*
                  * YUV is a special case where the stream_buf_size needs to be
                  * an integral multiple of 33.75 kB (storage for 32 screens
-                 * lines to maintain alignment in case of lost buffers
+                 * lines to maintain alignment in case of lost buffers).
+                 *
+                 * IDX is a special case where the stream_buf_size should be
+                 * an integral multiple of 1.5 kB (storage for 64 index entries
+                 * to maintain alignment in case of lost buffers).
+                 *
                  */
                 if (i == CX18_ENC_STREAM_TYPE_YUV) {
                         cx->stream_buf_size[i] *= 1024;
@@ -511,15 +519,24 @@ static void cx18_process_options(struct cx18 *cx)
                         if (cx->stream_buf_size[i] < CX18_UNIT_ENC_YUV_BUFSIZE)
                                 cx->stream_buf_size[i] =
                                                 CX18_UNIT_ENC_YUV_BUFSIZE;
+                } else if (i == CX18_ENC_STREAM_TYPE_IDX) {
+                        cx->stream_buf_size[i] *= 1024;
+                        cx->stream_buf_size[i] -=
+                           (cx->stream_buf_size[i] % CX18_UNIT_ENC_IDX_BUFSIZE);
+
+                        if (cx->stream_buf_size[i] < CX18_UNIT_ENC_IDX_BUFSIZE)
+                                cx->stream_buf_size[i] =
+                                                CX18_UNIT_ENC_IDX_BUFSIZE;
                 }
                 /*
-                 * YUV is a special case where the stream_buf_size is
+                 * YUV and IDX are special cases where the stream_buf_size is
                  * now in bytes.
                  * VBI is a special case where the stream_buf_size is fixed
                  * and already in bytes
                  */
                 if (i == CX18_ENC_STREAM_TYPE_VBI ||
-                    i == CX18_ENC_STREAM_TYPE_YUV) {
+                    i == CX18_ENC_STREAM_TYPE_YUV ||
+                    i == CX18_ENC_STREAM_TYPE_IDX) {
                         if (cx->stream_buffers[i] < 0) {
                                 cx->stream_buffers[i] =
                                         cx->options.megabytes[i] * 1024 * 1024