doc update

1 files changed, 26 insertions, 5 deletions

diff --git a/linux/Documentation/dvb/README.dibusb b/linux/Documentation/dvb/README.dibusb
index acd83e15d..0aa26cac1 100644
--- a/linux/Documentation/dvb/README.dibusb
+++ b/linux/Documentation/dvb/README.dibusb
@@ -69,8 +69,10 @@ Supported devices USB2.0
 - DiBcom USB2.0 DVB-T reference device (non-public)
 
 
-
 0. NEWS:
+  2004-11-23 - merged changes from DiB3000MC_ver2.1
+             - revised the debugging
+             - possibility to deliver the complete TS for USB2.0
   2004-11-21 - first working version of the dib3000mc/p frontend driver.
   2004-11-12 - added additional remote control keys. Thanks to Uwe Hanke.
   2004-11-07 - added remote control support. Thanks to David Matthews.
@@ -167,9 +169,7 @@ as a slave device in vdr, was not working for me. Some work has to be done
 2. Known problems and bugs
 
 TODO: 
-- remote control
 - signal-quality and strength calculations
-- i2c address probing
 
 2.1. Adding support for devices 
 
@@ -191,7 +191,29 @@ the dvb-dibusb.h-file and create a patch and send it over to me or to
 the linux-dvb mailing list, _after_ you have tried compiling and modprobing
 it.
 
-2.2. Comments
+2.2. USB1.1 Bandwidth limitation
+
+Most of the current supported devices are USB1.1 and thus they have a 
+maximum bandwidth of about 5-6 MBit/s when connected to a USB2.0 hub. 
+This is not enough for receiving the complete transport stream of a
+DVB-T channel (which can be about 16 MBit/s). Normally this is not a
+problem, if you only want to watch TV, but watching a channel while
+recording another channel on the same frequency simply does not work.
+This applies to all USB1.1 DVB-T devices.
+
+A special problem of the dibusb for the USB1.1 is, that the USB control
+IC has a problem with write accesses while having MPEG2-streaming 
+enabled. When you set another pid while receiving MPEG2-TS it happens, that
+the stream is disturbed and probably data is lost (results in distortions of 
+the video or strange beeps within the audio stream). DiBcom is preparing a 
+firmware especially for Linux which perhaps solves the problem.
+
+Especially VDR users are victoms of this bug. VDR frequently requests new PIDs
+due the automatic scanning (introduced in 1.3.x, afaik) and epg-scan. Disabling
+these features is maybe a solution. Additionally this behaviour of VDR exceeds 
+the USB1.1 bandwidth.
+
+2.3. Comments
   
 Patches, comments and suggestions are very very welcome
 
@@ -214,7 +236,6 @@ Patches, comments and suggestions are very very welcome
     user-level firmware loader, which saves a lot of time 
     (when writing the vp7041 driver)
 
-
    Ulf Hermenau for helping me out with traditional chinese.
    
    André Smoktun and Christian Frömmel for supporting me with