[mythtv-users] [mythtv] Dark Picture/Image and IRQ Lockup bug with
fix
jeremy smith
yahoo at belynnandjeremy.xohost.com
Sat Sep 18 20:13:08 EDT 2004
Software: The bttv driver for video capture cards with Fusion 8x8 PCI video
decoders
Version: Tested on v 0.9.15. Reports of the bug start with v 0.9.12.
Problem: Dark image/picture occurs at random times. Most often after
changing channels.
Cause: It starts with an IRQ lockup. However, as the driver recovers, it
configures the card again. This is done in the init_bt848 subroutine. As
expected, it sets brightness, contrast, hue and color/saturation. It then
configures the luma decimation filter. However, to set the filter bit it
simply writes to the entire O_CONTROL and E_CONTROL registers, as opposed to
masking the bit. The O_CONTROL and E_CONTROL registers also contain the MSB
of the saturation/color and contrast values. Thus, the MSB data that was
just setup a few statements above is lost.
Fix: Move the statements that set the brightness, contrast, hue and
color/saturation to after the luma decimation filter. There are 4 lines,
starting at 1056. Move them to 1068.
Ref: http://www.domenech.org/bt878a-adc/conexant-fusion_878a_datasheet.pdf
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