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  1. 29 7月, 2011 2 次提交
    • M
      [media] em28xx: Fix DVB-C maxsize for em2884 · f7acc4bb
      由 Mauro Carvalho Chehab 提交于 
      The logic at em28xx_isoc_dvb_max_packetsize() sucks, at least for newer
the needed packet size. Yet, it is better than nothing.

Rewrite the code in order to change the default to 752 for em2884 and
newer chips and provide a better way to handle per-chipset specifics.

For em2874, the current default should be enough, as the only em2874
board is currently a 1-seg ISDB-T board, so, it needs only a limited
amount of bandwidth.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
      f7acc4bb
    • M
      [media] tda18271c2dd: Fix saw filter configuration for DVB-C @6MHz · cf845297
      由 Mauro Carvalho Chehab 提交于 
      Currently, the driver assumes that all QAM carriers are spaced with
8MHz. This is wrong, and may decrease QoS on Countries like Brazil,
that have DVB-C carriers with 6MHz-spaced.

Fortunately, both ITU-T J-83 and EN 300 429 specifies a way to
associate the symbol rate with the bandwidth needed for it.

For ITU-T J-83 2007 annex A, the maximum symbol rate for 6 MHz is:
	6 MHz / 1.15 = 5217391 Bauds
For  ITU-T J-83 2007 annex C, the maximum symbol rate for 6 MHz is:
	6 MHz / 1.13 = 5309735 Bauds.

As this tuner is currently used only for DRX-K, and it is currently
hard-coded to annex A, I've opted to use the roll-off factor of 0.15,
instead of 0.13.

If we ever support annex C, the better would be to add a DVB S2API
call to allow changing between Annex A and C, and add the 0.13 roll-off
factor to it.

This code is currently being used on other frontends, so I think we
should later add a core function with this code, to warrant that
it will be properly implemented everywhere.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
      cf845297
  3. 28 7月, 2011 38 次提交