em28xx_isoc_dvb_max_packetsize for EM2884 (Terratec Cinergy HTC Stick)

[Dennis Sperlich <dsperlich@googlemail.com>]

Hi,

I have a Terratec Cinergy HTC Stick an tried the new support for the 
DVB-C part. It works for SD material (at least for free receivable 
stations, I tried afair only QAM64), but did not for HD stations 
(QAM256). I have only access to unencrypted ARD HD, ZDF HD and arte HD 
(via KabelDeutschland). The HD material was just digital artefacts, as 
far as mplayer could decode it. When I did a dumpstream and looked at 
the resulting file size I got something about 1MB/s which seems a little 
too low, because SD was already about 870kB/s. After looking around I 
found a solution in increasing the isoc_dvb_max_packetsize from 752 to 
940 (multiple of 188). Then an HD stream was about 1.4MB/s and looked 
good. I'm not sure, whether this is the correct fix, but it works for me.

If you need more testing pleas tell.

Regards,
Dennis



index 804a4ab..c518d13 100644
--- a/drivers/media/video/em28xx/em28xx-core.c
+++ b/drivers/media/video/em28xx/em28xx-core.c
@@ -1157,7 +1157,7 @@ int em28xx_isoc_dvb_max_packetsize(struct em28xx *dev)
                  * FIXME: same as em2874. 564 was enough for 22 Mbit DVB-T
                  * but not enough for 44 Mbit DVB-C.
                  */
-               packet_size = 752;
+               packet_size = 940;
         }

         return packet_size;