From: Mauro Carvalho Chehab Date: Thu, 28 Jul 2011 18:49:43 +0000 (-0300) Subject: [media] tda18271c2dd: Fix saw filter configuration for DVB-C @6MHz X-Git-Tag: v3.1-rc1~116^2~3 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cf845297d592339bcf0839298c4319633df3173a;p=pandora-kernel.git [media] tda18271c2dd: Fix saw filter configuration for DVB-C @6MHz 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: Mauro Carvalho Chehab --- Reading git-diff-tree failed